Phase I Study of the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of PTK787/ZK 222584 Administered Twice Daily in Patients W
http://www.100md.com
《临床肿瘤学》
the University of Leicester, Leicester, United Kingdom
Novartis Pharmaceuticals Corp, East Hanover, NJ
Schering AG, Berlin, Germany
ABSTRACT
PURPOSE: PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting all known vascular endothelial growth factor (VEGF) receptor tyrosine kinases, including VEGFR-1/Flt-1, VEGFR-2/KDR, VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase, and the c-kit protein tyrosine kinase. In this phase I dose-escalating study, PTK/ZK was administered bid to exploit the theoretical advantage of maintaining constant drug levels above a threshold known from preclinical data to interfere with VEGF receptor signaling.
PATIENTS AND METHODS: Forty-three patients with advanced cancers received single-agent PTK/ZK at doses of 150 to 1,000 mg orally bid. Assessments for safety and pharmacokinetics were performed. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used as a pharmacodynamic marker of response.
RESULTS: At 1,000 mg bid, the dose-limiting toxicity of reversible grade 3 lightheadedness was observed. Dose-related grade 3 fatigue and vomiting were observed but these were not dose-limiting. Pharmacokinetic data confirmed that PTK/ZK exposure increased with increasing dose up to 500 mg bid and appeared to plateau at higher doses. A greater than 40% reduction in the DCE-MRI bidirectional transfer constant (Ki) at day 2 predicted for nonprogression of disease.
CONCLUSION: The maximum-tolerated oral dose of PTK/ZK is 750 mg orally bid. DCE-MRI and pharmacokinetic data indicate that PTK/ZK 1,000 mg total daily dose is the biologically active dose.
INTRODUCTION
Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is essential for tumor growth and the spread of metastases.1,2 The vascular endothelial growth factor (VEGF) family of tumor-secreted angiogenic factors (VEGF-A, VEGF-B, VEGF-C, VEGF-D), which acts through the VEGF receptors (VEGFR-1, -2, and -3), are key mediators of tumor-induced neovascularization and enhancement of vascular permeability.2-4 These VEGFRs are central to tumor angiogenesis and lymphangiogenesis,5,6 binding extracellular VEGFs and triggering intracellular signaling though their tyrosine kinase domains.7-10 Currently available antiangiogenic therapy (anti–VEGF-A antibody) has been shown to hinder tumor-induced angiogenesis.11 It has therefore been postulated that antiangiogenic agents that target multiple VEGF receptors, the principal downstream mediators of angiogenesis and lymphangiogenesis, would more completely inhibit tumor growth and metastases.12
PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting all known VEGFR tyrosine kinases, including VEGFR-1/flt-1, VEGFR-2/KDR, and VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase, and the c-kit protein tyrosine kinase.13,14 In preclinical studies, PTK/ZK has been shown to inhibit growth and reduce microvasculature in subcutaneously implanted human tumor xenografts in nude mice.13,14 Developing suitable end points to assess the efficacy of angiogenesis inhibitors is challenging because these biologically targeted therapies are unlikely to cause rapid reduction of tumor volume15,16 Given that in healthy adults there is minimal angiogenesis occurring (apart from the premenopausal uterus and wound healing), it was anticipated that such agents would not be associated with significant toxicity. It was therefore postulated that the active dose could be less than the maximum-tolerated dose (MTD). We have demonstrated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a useful technique to help define the biologic response and optimal dose of PTK/ZK in other phase I studies.17 These studies involved administering PTK/ZK on a once-daily schedule, for which the drug half-life was shown to be 3 to 6 hours. From preclinical studies we were able to predict the threshold target above which there was maximal inhibition of VEGF receptor signaling.13 In view of the short half-life of the drug, this study was run in parallel with our other studies to ascertain whether the administration of PTK/ZK bid would maintain more constant blood levels above this therapeutic target. We hypothesized that this could translate into a potentially more efficacious schedule. We therefore undertook a dose-finding study using PTK/ZK bid in patients with advanced malignancies to establish the pharmacokinetic profile and safety of this schedule. DCE-MRI was incorporated as a pharmacodynamic end point. This is the first full report of the results of a phase I study of an oral VEGFR tyrosine kinase inhibitor.
PATIENTS AND METHODS
Patient Selection
Patients eligible for the study were older than 18 years and had histologic or cytologic confirmation of malignancy that was refractory to standard therapy or for which no effective standard treatment was available. Disease had to be measurable by Southwest Oncology Group criteria, and although previous chemotherapy, biologic, and radiotherapy treatments were permitted, patients had to have recovered from the toxic effects of therapy. The patients also had to be able to tolerate repeated MRI scans. All patients had to have a WHO performance status of 0 to 2, absolute neutrophil count 1.5 x 109/L, hemoglobin 9 g/dL, platelets 100 x 109/L, AST and ALT 2.5x upper limit of normal (ULN), serum bilirubin 1.5x ULN, serum creatinine 1.5x ULN, 24-hour creatinine clearance 50 mL/min, and no evidence of brain metastases. Any concurrent medical conditions had to be well controlled, and concomitant use of warfarin derivatives was not permitted. Treatment with aspirin or heparin was allowed. Patients had to have a projected life expectancy of at least 3 months. The local medical ethics committee approved the protocol and patients gave their written informed consent according to Good Clinical Practice (ICH/EU-GCP) regulation before being registered.
Study Design
This phase I trial was designed as an open-label, nonrandomized, dose-escalation study. Patients were recruited in cohorts of three to six and received sequentially increasing doses of PTK/ZK until dose-limiting toxicity (DLT) was observed. Four dose levels were scheduled: 150, 250, 500, and 1,000 mg bid. The MTD and/or biologically active dose cohort was expanded to include 17 additional patients to further evaluate safety, tolerability, pharmacokinetics, and biologic activity. During the study, dose-escalation decisions were based on data from patients treated for at least 4 weeks. No intrapatient dose escalation was permitted. Adverse events were assessed weekly during the first 8 weeks of treatment and every 2 weeks thereafter.
Treatment was administered until disease progression, unacceptable toxicity, or patient refusal to continue. US National Cancer Institute Common Toxicity Criteria (version 2.0) were used for safety evaluation. The MTD was defined as the dose that produced DLT effects in one of six assessable patients, where at least two patients experienced DLT effects at the next higher dose level. Dose-limiting toxic effects could be hematologic or nonhematologic and occurred within the first 28 days of treatment. Dose-limiting toxic effects were defined as grade 4 neutropenia, grade 4 anemia, grade 4 thrombocytopenia, any grade 3 to 4 nonhematologic toxicity except for controllable nausea and vomiting, grade 3 to 4 fever from an identified source, or grade 3 to 4 alkaline phosphatase elevation. There was a planned expansion of the cohort at MTD to evaluate further safety, tolerability, biologic activity, and pharmacokinetics.
Within 14 days before treatment, patients had their medical history taken, physical examination with clinical tumor measurement, assessment of performance status, full hematologic status and blood chemistry (urea, creatinine, sodium, potassium, calcium, glucose, bilirubin, alkaline phosphatase, AST, ALT, serum lactate dehydrogenase, and albumin), urinalysis, ECG, chest radiography, and assessment of tumor parameters using DCE-MRI. During treatment, hematologic and biochemical tests were repeated weekly for the first 8 weeks and every 2 weeks thereafter.
Plasma and serum markers of angiogenesis and activated endothelial cells were collected. These will be reported in a separate article.
During the conduct of this trial, unexpected preclinical findings were observed and all clinical trials with PTK/ZK were placed on temporary clinical hold. The trials were resumed after further preclinical evaluation (see Results), and additional safety evaluations have been incorporated.
Drug Supply
PTK/ZK (Novartis, East Hanover, NJ, and Schering AG, Berlin, Germany) was provided in 50- and 100-mg tablets and 250-mg capsules and given orally, with a 2-hour fast before and after the administration of the drug. The second dose was administered approximately 8 hours after the morning dose. Patients were dosed continuously, with a treatment cycle defined as 28 days.
Analytic Assay
PTK/ZK assay was performed using high-performance liquid chromatography (HPLC). PTK/ZK was extracted from the plasma sample by a liquid-liquid extraction and detected using UV detection at 315 nm. The chemical name of the internal standard is CGP80805(4 chloro-phenyl)-[4-2, 6-dimethyl-pyridylmethyl phthalazin-1-yl]) amine, C22H19ClN4
molecular weight, 374.87. The lower limit of quantification was 2.5 ng/mL, with a concentration range of 2.5 to 10,000 ng/mL. To each 0.25 mL of plasma sample, 15 μL of internal standard (10 μg/mL), 500 μL 0.1 N NaOH, and 5.5 mL t-butylmethyl-ether were pipetted into a 10-mL conical glass tube. The tube was shaken in an overhead shaker for 10 minutes. After 5 minutes of centrifugation at 4,000 rpm, the organic layer was transferred into another tube and evaporated to dryness under a nitrogen stream at 40°C. The residue was redissolved in 100 μL of mobile phase and 75 μL was injected into the HPLC system. The mobile phase of the HPLC system consists of 5 g ammonium acetate, 1,250 mL of distilled water, and 600 g of acetonitrile brought to pH 6.5 with phosphoric acid. The HPLC system uses an Inertsil column, 125 x 2 mm, 5 μm (Phenomenex, Torrance, CA). The isocratic elution is completed at a flow rate of 0.4 mL/min. At a concentration of 20, 800, and 8,000 ng/mL, the intraday variability (percent coefficient of variation [CV%]) is 0.7, 1.4, and 1.3, respectively. At a concentration of 20, 800, and 8,000 ng/mL, the interday variability (CV%) is 1.3, 2.0, and 1.6, respectively. The CV% for the assay sensitivity at 2.50 ng/mL is 4.0.
Pharmacokinetics
Full pharmacokinetic samples were collected on days 1 and 28 at the following time points: predose (0), 0.5, 1, 2.5, 4, 8, 8.5, 10, 13, and 24 hours postdose. Additional samples were taken at days 15 and 22 during cycle 1, and days 15 and 28 during cycle 2. Blood (3 mL) was collected into precooled (using an ice bath) heparinized tubes and gently inverted eight to 10 times and immediately placed in the ice bath. Within 30 minutes, plasma was prepared by centrifugation (approximately 2,000 x g at 4°C for 10 minutes). After centrifugation, plasma was transferred by pipet to a polypropylene cryogenic freezing vial and stored frozen at –80°C until shipment and analysis.
The pharmacokinetic parameters, including area under the plasma concentration curve (AUC), maximum plasma concentration (Cmax) after first daily dose, time to peak concentration (tmax) after the first daily dose, and minimum plasma concentration (Cmin), were determined for each individual plasma concentration-time data on days 1 and 28. The Cmax and Cmin were determined on days 1 and 28 by visual inspection of each patient's plasma concentration. Using the noncompartmental method (WinNonlin Pro 3.2
Pharsight Corp), AUC0-24 was calculated on days 1 and 28 using the linear trapezoidal rule up to 24 hours postdose.
DCE-MRI
MRI was performed at baseline (within 7 to 14 days before treatment with PTK/ZK). Additional studies were performed on day 2 and at the end of each 28-day cycle. Patients were imaged between 2 to 9 hours after the first dose on these days. All MRIs were acquired using a 1.5-Tesla whole-body magnet equipped with 25 mT/m gradient coils and phased array surface coils (Magnetom Vision
Siemens, Erlangen, Germany). All patients underwent a transverse, breath-held, T1-weighted, gradient-recalled echo examination to measure tumor dimensions. An inversion recovery snapshot flash sequence (turbo FLASH
Siemens) was used for the DCE-MRI study to freeze bulk motion of metastases during imaging.17 The inversion time (TI, 850 milliseconds) was chosen so that the metastases had approximately zero intensity before contrast injection, and increased in brightness as the contrast agent washed into the tissue. Representative disease sites were identified and then used for all subsequent scans. Signal intensities were taken from regions of interest drawn around the tumor and aorta separately using an image analysis package, Analyze (Mayo Clinic, Rochester, MN). The bidirectional transfer constant (Ki, in milliliters per 100 g per minute [similar to Ktrans]) was then calculated using a two-compartment model as previously described.18
Tumor Assessments
Patients were evaluated for tumor response at the end of every 28-day cycle using the Southwest Oncology Group Solid Tumor Response Criteria. All measurable, assessable, and nonassessable lesions were accounted for in the tumor assessment. Measurable lesions were quantified by using the product of perpendicular diameters. Complete response (CR) was defined as the complete disappearance of all measurable and assessable disease, and with no new lesions or disease-related symptoms. Partial response (PR) was defined as at least a 50% decrease in the sum of the product of the perpendicular diameters of measurable lesions from baseline and with no development of new lesions. Minor response (MR) was defined as at least 25% but not more than 50% decrease from baseline in measurable lesions. Progressive disease (PD) was defined as at least a 50% increase or an increase of 10 cm2 (whichever is smaller) in measurable lesions, clear worsening from previous assessment of any assessable disease, reappearance of any lesion that had disappeared, or appearance of any new lesion/site. Stable disease (SD) was defined as the disease status for which both the measurable lesions were less than the criterion to meet PR, but also not sufficient to meet the criterion for PD.
The best response criteria were used to categorize all assessable patients as having either nonprogressive or progressive disease according to the biomarker analysis to identify the differences in biologic effects in response to PTK/ZK. The best response was determined from the sequence of tumor response: CR, if two CRs occurred before progression (category 1)
PR, if two PRs occurred before progression (category 2)
SD, if two SDs occurred before progression (category 3)
PD, if one PD occurred within the first 2 months of treatment (category 4). Patients with nonprogressive disease were defined as belonging to category 1, 2, and 3, whereas patients with progressive disease were defined as belonging to category 4.
DCE-MRI Statistical Methods and Modeling
Analysis was performed on all cancer types, and in certain cases, performed for a homogeneous subpatient population with liver metastases. As observed previously, the relative rather than absolute changes of Ki are more clinically meaningful because of variability in baseline enhancement of tumors. The variability may be a result of varying sizes or degree of necrosis of tumors at the start of PTK/ZK treatment, and should be accounted for by using an enhancement parameter expressed as a percentage of the baseline value (percentage of baseline MRI Ki).17
The overall effect of PTK/ZK on MRI Ki was evaluated. The mean percentage of baseline MRI Ki and SE by time point (days 2, 28) for doses lower than 1,000 mg and doses 1,000 mg were calculated and graphically assessed. Mean percentage of baseline MRI Ki and SE by time point (days 2, 28) for patients with progressive versus nonprogressive disease were calculated and statistically assessed. Where means are compared statistically, the nonparametric Wilcoxon signed rank test is used for paired data and the Mann-Whitney U test is used for independent data. Where percentages are compared, the 2 test is used. The degree of association between percentage of baseline MRI Ki and tumor size by day 56, dose, AUC, Cmax, and Cmin were measured by the Spearman rank correlation coefficient (Statistical Package for the Social Sciences [SPSS] version 12.0 for Windows
SPSS Inc, Chicago, IL). The percentage change in tumor size by day 56 was plotted against MRI Ki on day 2.
To describe further the relationship between percentage of baseline MRI Ki and PTK/ZK exposure, pharmacodynamic modeling was performed by fitting the data to an inhibitory Emax model:
where effect is the percentage of baseline MRI Ki, E0 is baseline, EAUC50 is AUC in which 50% of Emax is achieved, and Emax is the maximum effect.
Given that a clear association exists between percentage of baseline MRI Ki versus AUC, the effect of MRI was fitted to AUC. As described previously, to compensate for limited data points, the modeling was performed using pooled data from days 2 and 28 to best characterize the entire inhibitory Emax curve.17
RESULTS
Patient Characteristics
Forty-three patients with advanced cancer were enrolled onto the study
26 patients in the dose-escalation phase and 17 patients in the expansion phase at the MTD. Patient characteristics are listed in Table 1. Of the four patients with sarcomas, two had GI stromal tumors (GIST) expressing c-kit. There were six patients with neuroendocrine tumors enrolled
three arising from the pancreas and three from the gut.
Twenty-six patients were entered into the dose-escalation portion of the study. Two patients experienced disease progression before receiving one complete cycle, one patient experienced disease-related adverse events during cycle 1, and one patient was noncompliant
these four patients were replaced for evaluation of MTD. An additional two patients discontinued treatment prematurely during the first month of treatment because of a clinical hold. During the conduct of the trial, unexpected preclinical findings of duodenal hyperplasia and adenosis with reversible reactive hyperproliferation in rats after longer-term treatment were observed. All clinical trials with PTK/ZK were put on clinical hold. No such changes were seen in either dogs or mice. All patients subsequently treated with PTK/ZK underwent endoscopy or barium examinations every 3 months. No hyperplastic changes were documented and the phase III studies have continued without the need for upper GI monitoring after discussion with the US Food and Drug Administration. Therefore, six patients were not assessable to determine MTD and were replaced.
For assessment of efficacy, the following patients were considered not assessable: the three patients whose therapy was interrupted because of a clinical hold (two patients did not complete cycle 1 and the third patient was just starting cycle 2), two patients who discontinued because of adverse events before completing cycle 1, one patient who withdrew consent during cycle 1, and one patient with breast cancer who took concurrent tamoxifen. Thus, seven of 43 patients were not assessable for response.
Three patients had liver metastases on the DCE-MRI imaging that were too small to measure and could not be evaluated in this part of the study. One patient's baseline DCE-MRI examination was not of sufficient quality to allow comparison of subsequent scans. Thus, a total of eight patients were not eligible for DCE-MRI evaluations.
Toxicities and Tolerability
All patients were assessable for toxicity. Table 2 shows the number of patients treated at each dose level and the percentage experiencing adverse events regardless of relation to study medication. The DLT experienced by two of three patients enrolled at 1,000 mg bid was grade 3 lightheadedness
the third patient had grade 2 lightheadedness. Lightheadedness with accompanying grade 3 ataxia and lethargy led one patient in the 1,000-mg bid cohort to withdraw from the study. The other patient completed his first cycle at 1,000 mg bid without dose reduction or interruption
however, grade 2 lightheadedness led to subsequent dose reductions to 750 mg and then 500 mg bid. Lightheadedness occurred in all dosing cohorts
one of six (17%) in the 150-mg bid cohort, one of four (25%) in the 250-mg bid cohort, one of three (33%) in the 500-mg bid cohort, eight of 27 (30%) in the 750-mg bid cohort, and three of three (100%) in the 1,000-mg bid cohort. This symptom was reported to start on day 1 or 2 of therapy, and for some patients occurred within an hour after ingesting PTK/ZK. The lightheadedness was often accompanied by intermittent nausea and vomiting and patients likened it to the feeling of alcohol intoxication. At worst it remained for as long as a week and then resolved spontaneously or subsided to a tolerable level with a reduction in PTK/ZK to the next dose level. This symptom appears to be dose related, with increasing severity and frequency with increasing dose. It was not associated with hypotension and was only associated with the cerebellar neurologic finding of ataxia in the patients experiencing grade 3 lightheadedness at the highest dose level.
The most common adverse event was nausea and vomiting, occurring in 61% and 54% of patients, respectively (Table 3) . These events were usually grade 1 or 2 and were easily managed with antiemetics and never required 5-hydroxytryptamine-3 receptor antagonists. Diarrhea occurred in 16% of patients and was thought to be related to PTK/ZK in 9% of patients. Only one patient experienced grade 3 diarrhea
all other occurrences were grades 1 or 2. Fatigue was seen in 37%, back pain in 26%, abdominal pain in 23%, and anorexia in 14% of patients
these are commonly observed cancer-related events.
The only significant cardiovascular adverse event noted was hypertension in seven patients (16%): grade 1 in one patient, grade 2 in two patients, and grade 3 in four patients. Two of the six patients had pre-existing hypertension that had previously been well controlled with beta blockers, diuretics, or both. When hypertension occurred or worsened on study, PTK/ZK was withheld while the antihypertensives were started or increased. Hypertension occurred in the first cycle of therapy for six of the seven patients, appearing as early as day 1 and as late as day 85. It was not associated with lightheadedness. Two patients who experienced grade 3 hypertension required a dose reduction of PTK/ZK from 750 to 500 mg bid. One patient who had pre-existing hypertension developed unsteadiness after receiving PTK/ZK for 20 cycles. An MRI of the brain confirmed a small cerebral infarct. She was withdrawn from the study because this was possibly related to PTK/ZK. No other potential embolic events were observed. The only thrombotic events reported were a superficial thrombophlebitis of the thigh and a thrombophlebitis of the wrist.
Three patients had normal cholesterol levels at entry and developed grade 3 elevations on study. Two were treated with statins, which controlled the lipids effectively in one of the patients. The third patient, who experienced a gradual increase in cholesterol during a period of months, was not treated.
Six patients (14%) had a grade 3 increase in ALT and AST
all patients had normal liver function at trial entry. In three patients, these occurrences were attributed to PTK/ZK and in three patients they were related to other medication and disease progression. All patients had metastatic disease involving the liver. Four patients in the 750-mg bid cohort had grade 3 elevations, two of which were deemed to be related to the drug.
Only one hematologic adverse event was attributed to PTK/ZK. This was neutropenia observed in one patient in the 750-mg bid expansion cohort, who received prior fluorouracil and irinotecan. This patient entered onto the study with an absolute neutrophil count of 1.5 x 109/L (grade 1) and the grade 3 event resolved with interruption of PTK/ZK. It did not recur when study medication was restarted at a reduced dose of 500 mg bid.
One patient had a grade 3 rash associated with PTK/ZK. This rash was present on both hands and consisted of symmetric raised red plaques that were confluent in areas. Skin biopsies revealed no vasculitis or eosinophilia. However, PTK/ZK was held and the rash improved
the rash reappeared with the reintroduction of PTK/ZK and was managed with a dose reduction to 500 mg bid and topical corticosteroids.
Pharmacokinetics
Thirty-eight (day 1) and 29 (day 28) patient profiles are available for pharmacokinetic analysis. The mean plasma concentration versus time profile on days 1 and 28 are depicted in Figure 1 for bid dosing at 750 mg (1,500 mg/d). PTK/ZK was rapidly absorbed after oral administration with a Cmax reached in approximately 2 hours. At steady-state, which was achieved by day 28, the systemic exposure (AUC) was approximately 40% lower than the exposure after a single dose for all doses (Fig 2). Metabolism via the CYP3A4 isoenzyme is the major elimination pathway, and autoinduction of this enzyme is likely to be the explanation for the observed decrease in AUC from days 1 to 28. The half-life was estimated from other PTK/ZK daily dosing studies17 and was determined to be approximately 3 to 6 hours on both days 2 and 28. PTK/ZK exposure increases with increasing dose up to 500 mg bid (1,000 mg/d) and appears to plateau above this dose level. In general, the dose- and time-dependent pharmacokinetic findings for bid dosing are similar to those observed for once-daily dosing.17 At equivalent total daily doses, AUC and Cmax for both the bid and once-daily dosing were similar on days 1 and 28
however, as expected, there were significantly higher trough concentrations achieved at steady-state for bid dosing (88%
P = .0096).
Pharmacodynamic Results of DCE-MRI
Of the 43 patients enrolled onto the study, 35 patients had DCE-MRI scans that are available for assessment (35 patients on day 2, 29 on day 28, and 18 on day 56). Of these 35 patients, 30 were assessable for tumor response. For statistical analysis of the MRI results, these patients were divided into two groups: patients with progressive and nonprogressive disease. A rapid reduction in enhancement was observed by day 2 after PTK/ZK treatment in all patients. Respectively, on days 2, 28, and 56 for all dose groups, the mean (± SE) percentage of baseline MRI Ki is 60.2 (± 5.5
P < .0001), 66.2 (± 6.9
P = .0003), and 64.2 (± 10.0
P = .006). As shown in Figure 3, the reduction is more pronounced with the higher dose group ( 1,000 mg/d) on both days 2 and 28 of treatment. Respectively, on days 2 and 28, the mean (± SE) percentage of baseline MRI Ki is 53.8 (± 6.5
P < .0001) and 60.4 (± 8.1
P = .001) for the 1,000 mg/d dose group, and 76.3 (± 8.8) and 88.5 (± 8.0) for the less than 1,000 mg/d dose group. In addition, the liver metastases subpopulation showed similar mean (± SE) percentage of baseline MRI Ki on days 2 and 28. The reduction in MRI Ki for the higher dose compared with lower dose group is statistically significant at day 2 (P = .02) and of borderline significance at day 28 (P = .053) for all patient types.
As in our previous study,17 patients who achieved nonprogressive disease status responded to PTK/ZK treatment with a greater reduction in enhancement on days 2 and 28. This was predicted by a greater than 40% reduction of baseline MRI Ki on day 2 of treatment (MRI Ki < 60% of baseline). For more than 40% and less than 40% reduction in MRI Ki, the rates of nonprogressive disease status are 89% v 41%, respectively (P = .006). Supporting this finding is Figure 4, which demonstrates that changes in percentage of baseline MRI Ki are positively associated with percentage change in tumor size by day 56 of PTK/ZK treatment (Spearman rank correlation coefficient 0.43
P = .023) with greater than 40% reduction in Ki resulting in target lesion shrinkage. In the patients who were off study by day 28, the percentage change in tumor size on day 28 was used.
A significant negative relationship was found between increasing PTK/ZK dose (in milligrams
P = .03), AUC (P < .0001), Cmin (P = .0001), and Cmax (P < .0001) with reducing enhancement on day 2 of treatment, and between PTK/ZK AUC (P = .03) and Cmin (P = .006) with reducing enhancement on day 28 of treatment (Table 4). The relationship between percentage of baseline MRI Ki versus AUC is characterized further by an inhibitory Emax model (Fig 5). The estimated pharmacodynamic parameters are (AUC): E0 = 99.6% of baseline MRI Ki (CV%, 108.2), EAUC50 = 28,046 hr · ng/mL (CV% = 414.0), and Emax = 28.1% of baseline MRI Ki (CV% = 43.7).
Antitumor Activity
Although efficacy was not the primary end point in this phase I study, antitumor activity was evaluated. No patients achieved CR. Of the 36 patients assessable for response, 11 patients had PD. Of these, six patients received 500 mg bid. The other five patients were at the 750-mg bid dose level
three patients experienced disease progression before the end of the first cycle. One patient with GIST had a PR in the pelvic recurrence and continues on the study. In another patient who had liver metastases from colon cancer, a PR was seen in the target liver lesions. This patient developed small bowel obstruction and underwent surgery, and therefore did not have a confirmatory scan at 28 days to verify PR. Seven patients had MRs, as documented by the investigator. Five of these patients had liver metastases from colorectal disease, one had liver metastases from a neuroendocrine tumor, and one had GIST. Because only CR, PR, or SD and not MR were the choices for response on the case record form, a total of 24 patients had the best response of SD reported.
An encouraging aspect of the trial was the length of time some patients were participating in the study, with a median of four cycles given overall. Seven patients participated in the study for at least 12 months, nine patients participated for 6 to 11 months, and seven patients continue to participate in the study. Of these, one patient with a neuroendocrine tumor of the pancreas with liver metastases has been participating in the study for more than 24 months. His status deserves special mention because he presented with severe abdominal pain that was uncontrolled with simple analgesics and a nerve block was planned. Within a few days of commencing PTK/ZK 750 mg bid, the pain completely subsided. Interestingly, during this time his previously controlled hypertension became uncontrolled, and he developed a grade 3 increase in liver ALT and AST. His observations normalized after a short break from PTK/ZK, during which time his pain recurred. An additional antihypertensive agent was introduced and a reduction in PTK/ZK to 500 mg bid was made. The MRI measurements confirmed that he had an MR in the liver lesions and stabilization of the tumor mass in his pancreas. He continued to participate in the study and has received more than 24 cycles of treatment with PTK/ZK.
Patients with colorectal cancer and liver metastases also appeared to do particularly well. Two women with actively progressing liver metastases from colorectal cancer after surgery (including liver resection) and chemotherapy (irinotecan in one patient and oxaliplatin and infused fluorouracil plus leucovorin [FOLFOX] in the other) had stabilization of their disease for 10 and 22 months, respectively. Another interesting occurrence was a patient with marked ascites and peritoneal disease from a primary gastric tumor. Because the VEGF pathway is a potent inducer of vascular permeability,4 we hypothesized that PTK/ZK may be useful in patients with ascites. Clearly, ascites is a difficult site of disease to assess for response. Nevertheless, this patient has had clinically SD not requiring paracentesis and has been receiving PTK/ZK 750 mg bid for more than 10 cycles.
DISCUSSION
When this study was designed, it was considered that the biologically active dose of PTK/ZK would not necessarily be the same as the MTD. Indeed, it was not clear from the preclinical data whether any toxicity would be evident. DLT however, was observed in this trial using PTK/ZK on a continuous basis bid in patients with advanced cancer. The DLT was grade 3 lightheadedness observed at 1,000 mg bid, and to a lesser degree at the lower dose levels. A variety of symptoms accompanied the lightheadedness. In the worst case, ataxia and dysarthria with lightheadedness caused the patients to be bedbound. In the mild cases, dizziness was not at all incapacitating. For the majority of patients who experienced lightheadedness, the symptom subsided during several days, with no dose adjustment of PTK/ZK necessary. The etiology of this adverse event is not clear
it may occur less than 1 hour after ingestion of the drug but usually appears by day 2. Thus, the lightheadedness may be related to early high exposure and will be evaluated further in other studies.
Adverse events associated with PTK/ZK are generally well tolerated at doses 750 mg bid, which is supported by the prolonged duration of treatment of some of our study patients. Exacerbation of pre-existing hypertension in patients with previously well-controlled blood pressure was also observed as an adverse event. The hypertension is easily controlled with standard medication. Hypertension has been observed with all of the oral VEGF tyrosine kinase inhibitors, although to date these findings have only been reported in abstract form. We postulate that this is due to the action of VEGF on the nitric oxide pathway.19 One patient experienced grade 3 neutropenia, and had entered the study with a grade 1 neutropenia. VEGF receptors are present on bone marrow progenitor cells and this event may have been related to PTK/ZK.20
Findings from this study further support the use of DCE-MRI as a biomarker for assessment of biologic activity with antiangiogenic agents. The reduction in MRI Ki was greater in patients with nonprogressive disease compared with those with progressive disease. A reduction in MRI Ki of greater than 40% is associated with a significant increase in likelihood of disease stabilization. The change in DCE-MRI was correlated with PTK/ZK exposure, including AUC, Cmax, and Cmin, and to a lesser extent with oral dose, especially on day 2. Therefore, relationship between AUC and MRI Ki was characterized by an inhibitory Emax model on day 2 and day 28 to explore the PK/PD relationship with DCE-MRI in early treatment and at steady-state with a bid regimen. The change in MRI Ki is consistent with previously reported data in colorectal cancer patients with liver metastases using the once-daily PTK/ZK regimen.17 This sustained reduction in MRI Ki in the range of 40% to 50% up to day 56 was achieved by the majority of patients who received 1,000 mg/d (500 mg bid) or more. Furthermore, statistical analysis indicates that MRI Ki (day 2) is a strong predictive marker for disease stabilization, thus supporting the use of DCE-MRI as a biomarker for early assessment of tumor response.
In a previous publication, Morgan et al17 used DCE-MRI to define the biologically active dose of PTK/ZK
most patients with nonprogressive disease received a single daily dose of 1,000 mg. All but 10 patients in this bid study received total daily doses of 1,000 mg/d. Thus, 33 of the 43 patients were treated at a biologically active dose and only five experienced rapid disease progression. PTK/ZK administered bid produces prolonged periods of disease stabilization and tumor responses with similar frequency as those seen in patients receiving PTK/ZK on a once-daily schedule.17,21-24 In view of the interesting antitumor activity seen in patients with colorectal cancer in both the once-daily and bid dosing studies, PTK/ZK has been studied in combination with oxaliplatin and infused fluorouracil plus leucovorin (FOLFOX) as first-line treatment of patients with advanced colorectal cancer.25
this study, the MTD of PTK/ZK administered is 750 mg bid. The DCE-MRI results suggest that the biologically active dose of PTK/ZK is at least 1,000 mg/d. Pharmacokinetic data from this study show that at equivalent daily doses, drug exposure is comparable with the previous once-daily–dosing study
however, the trough levels are significantly higher with the bid dosing. Whether this will translate into improved efficacy is at this time unknown, and additional phase II studies with bid dosing will be necessary to address this important issue.
Although 750 mg bid is the MTD, low-grade toxicities were observed that could compromise compliance for chronic continuous administration. Given that the pharmacokinetic parameters and DCE-MRI changes both suggest a plateau of relation with dose more than 500 mg bid, it seems appropriate to recommend that future studies incorporate a total daily dose of 1,000 mg to minimize toxicity and thus allow chronic continuous administration. Given the potential to incorporate this agent into future long-term studies, for example as maintenance or adjuvant therapy, it is essential to choose a dose and schedule that achieve biologic activity but minimize the incidence of adverse events. This is the major challenge for the design of phase I studies with new targeted agents, and it is clearly essential to validate the pharmacodynamic end point used in this study, DCE-MRI (combined with pharmacokinetic assessments), in future trials with this and other angiogenesis inhibitors.
Authors' Disclosures of Potential Conflicts of Interest
The following authors or their immediate family members have indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. Employment: Andrea Kay, Novartis
Lucy Lee, Novartis
Eric Masson, Novartis
Dirk Laurent, Schering AG. Consultant/Advisory Role: William P. Steward, Ispen, Novartis, Roche. Stock Ownership: Andrea Kay, Novartis
Eric Masson, Novartis
Dirk Laurent, Schering AG. Honoraria: Anne L. Thomas, Novartis, Roche
Bruno Morgan, Schering AG
William P. Steward, Ispen, Novartis, Roche. For a detailed description of these categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and Disclosures of Potential Conflicts of Interest found in Information for Contributors in the front of each issue.
Acknowledgment
We thank all of the nursing and administrative staff from the oncology trials unit and the MRI radiographic staff from Leicester University Hospitals who have been involved with this study during the last 3 years. We also thank David Lebwohl, Marie Puccio-Pick, and Yu Yun Ho from Novartis Pharmaceuticals and Martina Poethig and Clemens Guenther from Schering AG for their support.
NOTES
Supported by Novartis Pharmaceuticals Corp, East Hanover, NJ, and Schering AG, Berlin, Germany.
Authors' disclosures of potential conflicts of interest are found at the end of this article.
REFERENCES
Folkman J: Anti-angiogenesis: New concept for therapy of solid tumors. Ann Surg 175:409-416, 1972
Ferrara N: Role of vascular endothelial growth in regulation of physiological angiogenesis. Am J Physiol Cell 280:C1358-C1366, 2001
Siemeister G, Martiny-Baron G, Marme D: The pivotal role of VEGF in tumor angiogenesis: Molecular facts and therapeutic opportunities. Cancer Metastasis Rev 17:241-248, 1998
Dvorak HF, Brown LF, Detmar M, et al: Vascular permeability factor/vascular endothelial growth factor, microvascular hyperpermeability, and angiogenesis. Am J Pathol 146:1029-1039, 1995
Shibuya M, Yamaguchi S, Yaname A, et al: Nucleotide sequences and expression of a novel human receptor-type tyrosine kinase gene (flt) closely related to the fms family. Oncogene 5:519-524, 1990
Terman BI, Dougher VM, Carrion ME, et al: Identification of the KDR tyrosine kinase as a receptor for vascular endothelial growth factor. Biochem Biophys Res Commun 187:1579-1586, 1992
Achen MG, Jeltsch M, Kukk E, et al: Vascular endothelial growth factor D (VEGF-D) is a ligand for the tyrosine kinases VEGF receptor 2 (Flk1) and VEGF receptor 3 (Flt4). Proc Natl Acad Sci U S A 95:548-553, 1998
Olofsson B, Pajusola K, Kaipainen A, et al: Vascular endothelial growth factor B, a novel growth factor for endothelial cells. Proc Natl Acad Sci U S A 93:2576-2581, 1996
Olofsson B, Korpelainen E, Pepper MS, et al: Vascular endothelial growth factor B (VEGF-B) binds to VEGF receptor-1 and regulates plasminogen activator activity in endothelial cells. Proc Natl Acad Sci U S A 95:11709-11714, 1998
Joukov V, Kaipainen A, Jeltsch M, et al: Vascular endothelial growth factors VEGF-B and VEGF-C. J Cell Physiol 173:211-215, 1997
Hurwitz H, Fehrenbacher L, Novotny W, et al: Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med 350:2335-2342, 2004
Arteaga CL: Molecular therapeutics: Is one promiscuous drug against multiple targets better than combinations of molecule-specific drugs. Clin Cancer Res 9:1231-1232, 2003
Wood JM, Bold G, Buchdunger E, et al: PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration. Cancer Res 60:2178-2189, 2000
Drevs J, Muller-Driver R, Wittig C, et al: PTK787/ZK 222584, a specific vascular endothelial growth factor-receptor tyrosine kinase inhibitor, affects the anatomy of the tumor vascular bed and the functional vascular properties as detected by dynamic enhanced magnetic resonance imaging. Cancer Res 62:4015-4122, 2002
Moertel CG, Hanley JA: The effect of measuring error on the results of therapeutic trials in advanced cancer. Cancer 38:388-394, 1976
James K, Eisenhauer E, Christian M, et al: Measuring response in solid tumors: Unidimensional versus bidimensional measurement. J Natl Cancer Inst 91:523-528, 1999
Morgan B, Thomas AL, Drevs J, et al: Dynamic contrast-enhanced magnetic resonance imaging as a biomarker for the pharmacological response of PTK787/ZK 222584, an inhibitor of the vascular endothelial growth factor receptor tyrosine kinases, in patients with advanced colorectal cancer and liver metastases: Results from two phase I studies. J Clin Oncol 21:3955-3964, 2003
Larsson HB, Fritz-Hansen T, Rostrup E, et al: Myocardial perfusion modeling using MRI. Magn Reson Med 35:716-726, 1996
Parikh AA, Ellis LM: The vascular endothelial growth factor family and its receptors. Hematol Oncol Clin N Am 18:951-971, 2004
Hattori K, Heissig B, Wu Y, et al: Placental growth factor reconstitutes hematopoiesis by recruiting VEGFR1(+) stem cells from bone-marrow microenvironment. Nat Med 8:841-849, 2002
Conrad C, Friedman H, Reardon D, et al: A phase I/II trial of single-agent PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in patients with recurrent glioblastoma multiforme (GBM). Proc Am Soc Clin Oncol 22:110, 2004 (abstr 1512)
Reardon D, Friedman H, Brada M, et al: A phase I/II trial of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in combination with either temozolomide or lomustine for patients with recurrent glioblastoma multiforme (GBM). Proc Am Soc Clin Oncol 22:110, 2004 (abstr 1513)
Schleucher N, Trarbach T, Junker U, et al: Phase I/II study of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor in combination with FOLFIRI as first-line treatment for patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 22:259, 2004 (abstr 3558)
George D, Michaelson D, Oh WK, et al: Phase I study of PTK787/ZK 222584 (PTK/ZK) in metastatic renal cell carcinoma. Proc Am Soc Clin Oncol 22:385, 2003 (abstr 1548)
Steward WP, Thomas AL, Morgan B, et al: Expanded phase I/II study of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in combination with FOLFOX4 as first-line treatment for patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 22:259, 2004 (abstr 3556)(Anne L. Thomas, Bruno Mor)
Novartis Pharmaceuticals Corp, East Hanover, NJ
Schering AG, Berlin, Germany
ABSTRACT
PURPOSE: PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting all known vascular endothelial growth factor (VEGF) receptor tyrosine kinases, including VEGFR-1/Flt-1, VEGFR-2/KDR, VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase, and the c-kit protein tyrosine kinase. In this phase I dose-escalating study, PTK/ZK was administered bid to exploit the theoretical advantage of maintaining constant drug levels above a threshold known from preclinical data to interfere with VEGF receptor signaling.
PATIENTS AND METHODS: Forty-three patients with advanced cancers received single-agent PTK/ZK at doses of 150 to 1,000 mg orally bid. Assessments for safety and pharmacokinetics were performed. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used as a pharmacodynamic marker of response.
RESULTS: At 1,000 mg bid, the dose-limiting toxicity of reversible grade 3 lightheadedness was observed. Dose-related grade 3 fatigue and vomiting were observed but these were not dose-limiting. Pharmacokinetic data confirmed that PTK/ZK exposure increased with increasing dose up to 500 mg bid and appeared to plateau at higher doses. A greater than 40% reduction in the DCE-MRI bidirectional transfer constant (Ki) at day 2 predicted for nonprogression of disease.
CONCLUSION: The maximum-tolerated oral dose of PTK/ZK is 750 mg orally bid. DCE-MRI and pharmacokinetic data indicate that PTK/ZK 1,000 mg total daily dose is the biologically active dose.
INTRODUCTION
Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is essential for tumor growth and the spread of metastases.1,2 The vascular endothelial growth factor (VEGF) family of tumor-secreted angiogenic factors (VEGF-A, VEGF-B, VEGF-C, VEGF-D), which acts through the VEGF receptors (VEGFR-1, -2, and -3), are key mediators of tumor-induced neovascularization and enhancement of vascular permeability.2-4 These VEGFRs are central to tumor angiogenesis and lymphangiogenesis,5,6 binding extracellular VEGFs and triggering intracellular signaling though their tyrosine kinase domains.7-10 Currently available antiangiogenic therapy (anti–VEGF-A antibody) has been shown to hinder tumor-induced angiogenesis.11 It has therefore been postulated that antiangiogenic agents that target multiple VEGF receptors, the principal downstream mediators of angiogenesis and lymphangiogenesis, would more completely inhibit tumor growth and metastases.12
PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting all known VEGFR tyrosine kinases, including VEGFR-1/flt-1, VEGFR-2/KDR, and VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase, and the c-kit protein tyrosine kinase.13,14 In preclinical studies, PTK/ZK has been shown to inhibit growth and reduce microvasculature in subcutaneously implanted human tumor xenografts in nude mice.13,14 Developing suitable end points to assess the efficacy of angiogenesis inhibitors is challenging because these biologically targeted therapies are unlikely to cause rapid reduction of tumor volume15,16 Given that in healthy adults there is minimal angiogenesis occurring (apart from the premenopausal uterus and wound healing), it was anticipated that such agents would not be associated with significant toxicity. It was therefore postulated that the active dose could be less than the maximum-tolerated dose (MTD). We have demonstrated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a useful technique to help define the biologic response and optimal dose of PTK/ZK in other phase I studies.17 These studies involved administering PTK/ZK on a once-daily schedule, for which the drug half-life was shown to be 3 to 6 hours. From preclinical studies we were able to predict the threshold target above which there was maximal inhibition of VEGF receptor signaling.13 In view of the short half-life of the drug, this study was run in parallel with our other studies to ascertain whether the administration of PTK/ZK bid would maintain more constant blood levels above this therapeutic target. We hypothesized that this could translate into a potentially more efficacious schedule. We therefore undertook a dose-finding study using PTK/ZK bid in patients with advanced malignancies to establish the pharmacokinetic profile and safety of this schedule. DCE-MRI was incorporated as a pharmacodynamic end point. This is the first full report of the results of a phase I study of an oral VEGFR tyrosine kinase inhibitor.
PATIENTS AND METHODS
Patient Selection
Patients eligible for the study were older than 18 years and had histologic or cytologic confirmation of malignancy that was refractory to standard therapy or for which no effective standard treatment was available. Disease had to be measurable by Southwest Oncology Group criteria, and although previous chemotherapy, biologic, and radiotherapy treatments were permitted, patients had to have recovered from the toxic effects of therapy. The patients also had to be able to tolerate repeated MRI scans. All patients had to have a WHO performance status of 0 to 2, absolute neutrophil count 1.5 x 109/L, hemoglobin 9 g/dL, platelets 100 x 109/L, AST and ALT 2.5x upper limit of normal (ULN), serum bilirubin 1.5x ULN, serum creatinine 1.5x ULN, 24-hour creatinine clearance 50 mL/min, and no evidence of brain metastases. Any concurrent medical conditions had to be well controlled, and concomitant use of warfarin derivatives was not permitted. Treatment with aspirin or heparin was allowed. Patients had to have a projected life expectancy of at least 3 months. The local medical ethics committee approved the protocol and patients gave their written informed consent according to Good Clinical Practice (ICH/EU-GCP) regulation before being registered.
Study Design
This phase I trial was designed as an open-label, nonrandomized, dose-escalation study. Patients were recruited in cohorts of three to six and received sequentially increasing doses of PTK/ZK until dose-limiting toxicity (DLT) was observed. Four dose levels were scheduled: 150, 250, 500, and 1,000 mg bid. The MTD and/or biologically active dose cohort was expanded to include 17 additional patients to further evaluate safety, tolerability, pharmacokinetics, and biologic activity. During the study, dose-escalation decisions were based on data from patients treated for at least 4 weeks. No intrapatient dose escalation was permitted. Adverse events were assessed weekly during the first 8 weeks of treatment and every 2 weeks thereafter.
Treatment was administered until disease progression, unacceptable toxicity, or patient refusal to continue. US National Cancer Institute Common Toxicity Criteria (version 2.0) were used for safety evaluation. The MTD was defined as the dose that produced DLT effects in one of six assessable patients, where at least two patients experienced DLT effects at the next higher dose level. Dose-limiting toxic effects could be hematologic or nonhematologic and occurred within the first 28 days of treatment. Dose-limiting toxic effects were defined as grade 4 neutropenia, grade 4 anemia, grade 4 thrombocytopenia, any grade 3 to 4 nonhematologic toxicity except for controllable nausea and vomiting, grade 3 to 4 fever from an identified source, or grade 3 to 4 alkaline phosphatase elevation. There was a planned expansion of the cohort at MTD to evaluate further safety, tolerability, biologic activity, and pharmacokinetics.
Within 14 days before treatment, patients had their medical history taken, physical examination with clinical tumor measurement, assessment of performance status, full hematologic status and blood chemistry (urea, creatinine, sodium, potassium, calcium, glucose, bilirubin, alkaline phosphatase, AST, ALT, serum lactate dehydrogenase, and albumin), urinalysis, ECG, chest radiography, and assessment of tumor parameters using DCE-MRI. During treatment, hematologic and biochemical tests were repeated weekly for the first 8 weeks and every 2 weeks thereafter.
Plasma and serum markers of angiogenesis and activated endothelial cells were collected. These will be reported in a separate article.
During the conduct of this trial, unexpected preclinical findings were observed and all clinical trials with PTK/ZK were placed on temporary clinical hold. The trials were resumed after further preclinical evaluation (see Results), and additional safety evaluations have been incorporated.
Drug Supply
PTK/ZK (Novartis, East Hanover, NJ, and Schering AG, Berlin, Germany) was provided in 50- and 100-mg tablets and 250-mg capsules and given orally, with a 2-hour fast before and after the administration of the drug. The second dose was administered approximately 8 hours after the morning dose. Patients were dosed continuously, with a treatment cycle defined as 28 days.
Analytic Assay
PTK/ZK assay was performed using high-performance liquid chromatography (HPLC). PTK/ZK was extracted from the plasma sample by a liquid-liquid extraction and detected using UV detection at 315 nm. The chemical name of the internal standard is CGP80805(4 chloro-phenyl)-[4-2, 6-dimethyl-pyridylmethyl phthalazin-1-yl]) amine, C22H19ClN4
molecular weight, 374.87. The lower limit of quantification was 2.5 ng/mL, with a concentration range of 2.5 to 10,000 ng/mL. To each 0.25 mL of plasma sample, 15 μL of internal standard (10 μg/mL), 500 μL 0.1 N NaOH, and 5.5 mL t-butylmethyl-ether were pipetted into a 10-mL conical glass tube. The tube was shaken in an overhead shaker for 10 minutes. After 5 minutes of centrifugation at 4,000 rpm, the organic layer was transferred into another tube and evaporated to dryness under a nitrogen stream at 40°C. The residue was redissolved in 100 μL of mobile phase and 75 μL was injected into the HPLC system. The mobile phase of the HPLC system consists of 5 g ammonium acetate, 1,250 mL of distilled water, and 600 g of acetonitrile brought to pH 6.5 with phosphoric acid. The HPLC system uses an Inertsil column, 125 x 2 mm, 5 μm (Phenomenex, Torrance, CA). The isocratic elution is completed at a flow rate of 0.4 mL/min. At a concentration of 20, 800, and 8,000 ng/mL, the intraday variability (percent coefficient of variation [CV%]) is 0.7, 1.4, and 1.3, respectively. At a concentration of 20, 800, and 8,000 ng/mL, the interday variability (CV%) is 1.3, 2.0, and 1.6, respectively. The CV% for the assay sensitivity at 2.50 ng/mL is 4.0.
Pharmacokinetics
Full pharmacokinetic samples were collected on days 1 and 28 at the following time points: predose (0), 0.5, 1, 2.5, 4, 8, 8.5, 10, 13, and 24 hours postdose. Additional samples were taken at days 15 and 22 during cycle 1, and days 15 and 28 during cycle 2. Blood (3 mL) was collected into precooled (using an ice bath) heparinized tubes and gently inverted eight to 10 times and immediately placed in the ice bath. Within 30 minutes, plasma was prepared by centrifugation (approximately 2,000 x g at 4°C for 10 minutes). After centrifugation, plasma was transferred by pipet to a polypropylene cryogenic freezing vial and stored frozen at –80°C until shipment and analysis.
The pharmacokinetic parameters, including area under the plasma concentration curve (AUC), maximum plasma concentration (Cmax) after first daily dose, time to peak concentration (tmax) after the first daily dose, and minimum plasma concentration (Cmin), were determined for each individual plasma concentration-time data on days 1 and 28. The Cmax and Cmin were determined on days 1 and 28 by visual inspection of each patient's plasma concentration. Using the noncompartmental method (WinNonlin Pro 3.2
Pharsight Corp), AUC0-24 was calculated on days 1 and 28 using the linear trapezoidal rule up to 24 hours postdose.
DCE-MRI
MRI was performed at baseline (within 7 to 14 days before treatment with PTK/ZK). Additional studies were performed on day 2 and at the end of each 28-day cycle. Patients were imaged between 2 to 9 hours after the first dose on these days. All MRIs were acquired using a 1.5-Tesla whole-body magnet equipped with 25 mT/m gradient coils and phased array surface coils (Magnetom Vision
Siemens, Erlangen, Germany). All patients underwent a transverse, breath-held, T1-weighted, gradient-recalled echo examination to measure tumor dimensions. An inversion recovery snapshot flash sequence (turbo FLASH
Siemens) was used for the DCE-MRI study to freeze bulk motion of metastases during imaging.17 The inversion time (TI, 850 milliseconds) was chosen so that the metastases had approximately zero intensity before contrast injection, and increased in brightness as the contrast agent washed into the tissue. Representative disease sites were identified and then used for all subsequent scans. Signal intensities were taken from regions of interest drawn around the tumor and aorta separately using an image analysis package, Analyze (Mayo Clinic, Rochester, MN). The bidirectional transfer constant (Ki, in milliliters per 100 g per minute [similar to Ktrans]) was then calculated using a two-compartment model as previously described.18
Tumor Assessments
Patients were evaluated for tumor response at the end of every 28-day cycle using the Southwest Oncology Group Solid Tumor Response Criteria. All measurable, assessable, and nonassessable lesions were accounted for in the tumor assessment. Measurable lesions were quantified by using the product of perpendicular diameters. Complete response (CR) was defined as the complete disappearance of all measurable and assessable disease, and with no new lesions or disease-related symptoms. Partial response (PR) was defined as at least a 50% decrease in the sum of the product of the perpendicular diameters of measurable lesions from baseline and with no development of new lesions. Minor response (MR) was defined as at least 25% but not more than 50% decrease from baseline in measurable lesions. Progressive disease (PD) was defined as at least a 50% increase or an increase of 10 cm2 (whichever is smaller) in measurable lesions, clear worsening from previous assessment of any assessable disease, reappearance of any lesion that had disappeared, or appearance of any new lesion/site. Stable disease (SD) was defined as the disease status for which both the measurable lesions were less than the criterion to meet PR, but also not sufficient to meet the criterion for PD.
The best response criteria were used to categorize all assessable patients as having either nonprogressive or progressive disease according to the biomarker analysis to identify the differences in biologic effects in response to PTK/ZK. The best response was determined from the sequence of tumor response: CR, if two CRs occurred before progression (category 1)
PR, if two PRs occurred before progression (category 2)
SD, if two SDs occurred before progression (category 3)
PD, if one PD occurred within the first 2 months of treatment (category 4). Patients with nonprogressive disease were defined as belonging to category 1, 2, and 3, whereas patients with progressive disease were defined as belonging to category 4.
DCE-MRI Statistical Methods and Modeling
Analysis was performed on all cancer types, and in certain cases, performed for a homogeneous subpatient population with liver metastases. As observed previously, the relative rather than absolute changes of Ki are more clinically meaningful because of variability in baseline enhancement of tumors. The variability may be a result of varying sizes or degree of necrosis of tumors at the start of PTK/ZK treatment, and should be accounted for by using an enhancement parameter expressed as a percentage of the baseline value (percentage of baseline MRI Ki).17
The overall effect of PTK/ZK on MRI Ki was evaluated. The mean percentage of baseline MRI Ki and SE by time point (days 2, 28) for doses lower than 1,000 mg and doses 1,000 mg were calculated and graphically assessed. Mean percentage of baseline MRI Ki and SE by time point (days 2, 28) for patients with progressive versus nonprogressive disease were calculated and statistically assessed. Where means are compared statistically, the nonparametric Wilcoxon signed rank test is used for paired data and the Mann-Whitney U test is used for independent data. Where percentages are compared, the 2 test is used. The degree of association between percentage of baseline MRI Ki and tumor size by day 56, dose, AUC, Cmax, and Cmin were measured by the Spearman rank correlation coefficient (Statistical Package for the Social Sciences [SPSS] version 12.0 for Windows
SPSS Inc, Chicago, IL). The percentage change in tumor size by day 56 was plotted against MRI Ki on day 2.
To describe further the relationship between percentage of baseline MRI Ki and PTK/ZK exposure, pharmacodynamic modeling was performed by fitting the data to an inhibitory Emax model:
where effect is the percentage of baseline MRI Ki, E0 is baseline, EAUC50 is AUC in which 50% of Emax is achieved, and Emax is the maximum effect.
Given that a clear association exists between percentage of baseline MRI Ki versus AUC, the effect of MRI was fitted to AUC. As described previously, to compensate for limited data points, the modeling was performed using pooled data from days 2 and 28 to best characterize the entire inhibitory Emax curve.17
RESULTS
Patient Characteristics
Forty-three patients with advanced cancer were enrolled onto the study
26 patients in the dose-escalation phase and 17 patients in the expansion phase at the MTD. Patient characteristics are listed in Table 1. Of the four patients with sarcomas, two had GI stromal tumors (GIST) expressing c-kit. There were six patients with neuroendocrine tumors enrolled
three arising from the pancreas and three from the gut.
Twenty-six patients were entered into the dose-escalation portion of the study. Two patients experienced disease progression before receiving one complete cycle, one patient experienced disease-related adverse events during cycle 1, and one patient was noncompliant
these four patients were replaced for evaluation of MTD. An additional two patients discontinued treatment prematurely during the first month of treatment because of a clinical hold. During the conduct of the trial, unexpected preclinical findings of duodenal hyperplasia and adenosis with reversible reactive hyperproliferation in rats after longer-term treatment were observed. All clinical trials with PTK/ZK were put on clinical hold. No such changes were seen in either dogs or mice. All patients subsequently treated with PTK/ZK underwent endoscopy or barium examinations every 3 months. No hyperplastic changes were documented and the phase III studies have continued without the need for upper GI monitoring after discussion with the US Food and Drug Administration. Therefore, six patients were not assessable to determine MTD and were replaced.
For assessment of efficacy, the following patients were considered not assessable: the three patients whose therapy was interrupted because of a clinical hold (two patients did not complete cycle 1 and the third patient was just starting cycle 2), two patients who discontinued because of adverse events before completing cycle 1, one patient who withdrew consent during cycle 1, and one patient with breast cancer who took concurrent tamoxifen. Thus, seven of 43 patients were not assessable for response.
Three patients had liver metastases on the DCE-MRI imaging that were too small to measure and could not be evaluated in this part of the study. One patient's baseline DCE-MRI examination was not of sufficient quality to allow comparison of subsequent scans. Thus, a total of eight patients were not eligible for DCE-MRI evaluations.
Toxicities and Tolerability
All patients were assessable for toxicity. Table 2 shows the number of patients treated at each dose level and the percentage experiencing adverse events regardless of relation to study medication. The DLT experienced by two of three patients enrolled at 1,000 mg bid was grade 3 lightheadedness
the third patient had grade 2 lightheadedness. Lightheadedness with accompanying grade 3 ataxia and lethargy led one patient in the 1,000-mg bid cohort to withdraw from the study. The other patient completed his first cycle at 1,000 mg bid without dose reduction or interruption
however, grade 2 lightheadedness led to subsequent dose reductions to 750 mg and then 500 mg bid. Lightheadedness occurred in all dosing cohorts
one of six (17%) in the 150-mg bid cohort, one of four (25%) in the 250-mg bid cohort, one of three (33%) in the 500-mg bid cohort, eight of 27 (30%) in the 750-mg bid cohort, and three of three (100%) in the 1,000-mg bid cohort. This symptom was reported to start on day 1 or 2 of therapy, and for some patients occurred within an hour after ingesting PTK/ZK. The lightheadedness was often accompanied by intermittent nausea and vomiting and patients likened it to the feeling of alcohol intoxication. At worst it remained for as long as a week and then resolved spontaneously or subsided to a tolerable level with a reduction in PTK/ZK to the next dose level. This symptom appears to be dose related, with increasing severity and frequency with increasing dose. It was not associated with hypotension and was only associated with the cerebellar neurologic finding of ataxia in the patients experiencing grade 3 lightheadedness at the highest dose level.
The most common adverse event was nausea and vomiting, occurring in 61% and 54% of patients, respectively (Table 3) . These events were usually grade 1 or 2 and were easily managed with antiemetics and never required 5-hydroxytryptamine-3 receptor antagonists. Diarrhea occurred in 16% of patients and was thought to be related to PTK/ZK in 9% of patients. Only one patient experienced grade 3 diarrhea
all other occurrences were grades 1 or 2. Fatigue was seen in 37%, back pain in 26%, abdominal pain in 23%, and anorexia in 14% of patients
these are commonly observed cancer-related events.
The only significant cardiovascular adverse event noted was hypertension in seven patients (16%): grade 1 in one patient, grade 2 in two patients, and grade 3 in four patients. Two of the six patients had pre-existing hypertension that had previously been well controlled with beta blockers, diuretics, or both. When hypertension occurred or worsened on study, PTK/ZK was withheld while the antihypertensives were started or increased. Hypertension occurred in the first cycle of therapy for six of the seven patients, appearing as early as day 1 and as late as day 85. It was not associated with lightheadedness. Two patients who experienced grade 3 hypertension required a dose reduction of PTK/ZK from 750 to 500 mg bid. One patient who had pre-existing hypertension developed unsteadiness after receiving PTK/ZK for 20 cycles. An MRI of the brain confirmed a small cerebral infarct. She was withdrawn from the study because this was possibly related to PTK/ZK. No other potential embolic events were observed. The only thrombotic events reported were a superficial thrombophlebitis of the thigh and a thrombophlebitis of the wrist.
Three patients had normal cholesterol levels at entry and developed grade 3 elevations on study. Two were treated with statins, which controlled the lipids effectively in one of the patients. The third patient, who experienced a gradual increase in cholesterol during a period of months, was not treated.
Six patients (14%) had a grade 3 increase in ALT and AST
all patients had normal liver function at trial entry. In three patients, these occurrences were attributed to PTK/ZK and in three patients they were related to other medication and disease progression. All patients had metastatic disease involving the liver. Four patients in the 750-mg bid cohort had grade 3 elevations, two of which were deemed to be related to the drug.
Only one hematologic adverse event was attributed to PTK/ZK. This was neutropenia observed in one patient in the 750-mg bid expansion cohort, who received prior fluorouracil and irinotecan. This patient entered onto the study with an absolute neutrophil count of 1.5 x 109/L (grade 1) and the grade 3 event resolved with interruption of PTK/ZK. It did not recur when study medication was restarted at a reduced dose of 500 mg bid.
One patient had a grade 3 rash associated with PTK/ZK. This rash was present on both hands and consisted of symmetric raised red plaques that were confluent in areas. Skin biopsies revealed no vasculitis or eosinophilia. However, PTK/ZK was held and the rash improved
the rash reappeared with the reintroduction of PTK/ZK and was managed with a dose reduction to 500 mg bid and topical corticosteroids.
Pharmacokinetics
Thirty-eight (day 1) and 29 (day 28) patient profiles are available for pharmacokinetic analysis. The mean plasma concentration versus time profile on days 1 and 28 are depicted in Figure 1 for bid dosing at 750 mg (1,500 mg/d). PTK/ZK was rapidly absorbed after oral administration with a Cmax reached in approximately 2 hours. At steady-state, which was achieved by day 28, the systemic exposure (AUC) was approximately 40% lower than the exposure after a single dose for all doses (Fig 2). Metabolism via the CYP3A4 isoenzyme is the major elimination pathway, and autoinduction of this enzyme is likely to be the explanation for the observed decrease in AUC from days 1 to 28. The half-life was estimated from other PTK/ZK daily dosing studies17 and was determined to be approximately 3 to 6 hours on both days 2 and 28. PTK/ZK exposure increases with increasing dose up to 500 mg bid (1,000 mg/d) and appears to plateau above this dose level. In general, the dose- and time-dependent pharmacokinetic findings for bid dosing are similar to those observed for once-daily dosing.17 At equivalent total daily doses, AUC and Cmax for both the bid and once-daily dosing were similar on days 1 and 28
however, as expected, there were significantly higher trough concentrations achieved at steady-state for bid dosing (88%
P = .0096).
Pharmacodynamic Results of DCE-MRI
Of the 43 patients enrolled onto the study, 35 patients had DCE-MRI scans that are available for assessment (35 patients on day 2, 29 on day 28, and 18 on day 56). Of these 35 patients, 30 were assessable for tumor response. For statistical analysis of the MRI results, these patients were divided into two groups: patients with progressive and nonprogressive disease. A rapid reduction in enhancement was observed by day 2 after PTK/ZK treatment in all patients. Respectively, on days 2, 28, and 56 for all dose groups, the mean (± SE) percentage of baseline MRI Ki is 60.2 (± 5.5
P < .0001), 66.2 (± 6.9
P = .0003), and 64.2 (± 10.0
P = .006). As shown in Figure 3, the reduction is more pronounced with the higher dose group ( 1,000 mg/d) on both days 2 and 28 of treatment. Respectively, on days 2 and 28, the mean (± SE) percentage of baseline MRI Ki is 53.8 (± 6.5
P < .0001) and 60.4 (± 8.1
P = .001) for the 1,000 mg/d dose group, and 76.3 (± 8.8) and 88.5 (± 8.0) for the less than 1,000 mg/d dose group. In addition, the liver metastases subpopulation showed similar mean (± SE) percentage of baseline MRI Ki on days 2 and 28. The reduction in MRI Ki for the higher dose compared with lower dose group is statistically significant at day 2 (P = .02) and of borderline significance at day 28 (P = .053) for all patient types.
As in our previous study,17 patients who achieved nonprogressive disease status responded to PTK/ZK treatment with a greater reduction in enhancement on days 2 and 28. This was predicted by a greater than 40% reduction of baseline MRI Ki on day 2 of treatment (MRI Ki < 60% of baseline). For more than 40% and less than 40% reduction in MRI Ki, the rates of nonprogressive disease status are 89% v 41%, respectively (P = .006). Supporting this finding is Figure 4, which demonstrates that changes in percentage of baseline MRI Ki are positively associated with percentage change in tumor size by day 56 of PTK/ZK treatment (Spearman rank correlation coefficient 0.43
P = .023) with greater than 40% reduction in Ki resulting in target lesion shrinkage. In the patients who were off study by day 28, the percentage change in tumor size on day 28 was used.
A significant negative relationship was found between increasing PTK/ZK dose (in milligrams
P = .03), AUC (P < .0001), Cmin (P = .0001), and Cmax (P < .0001) with reducing enhancement on day 2 of treatment, and between PTK/ZK AUC (P = .03) and Cmin (P = .006) with reducing enhancement on day 28 of treatment (Table 4). The relationship between percentage of baseline MRI Ki versus AUC is characterized further by an inhibitory Emax model (Fig 5). The estimated pharmacodynamic parameters are (AUC): E0 = 99.6% of baseline MRI Ki (CV%, 108.2), EAUC50 = 28,046 hr · ng/mL (CV% = 414.0), and Emax = 28.1% of baseline MRI Ki (CV% = 43.7).
Antitumor Activity
Although efficacy was not the primary end point in this phase I study, antitumor activity was evaluated. No patients achieved CR. Of the 36 patients assessable for response, 11 patients had PD. Of these, six patients received 500 mg bid. The other five patients were at the 750-mg bid dose level
three patients experienced disease progression before the end of the first cycle. One patient with GIST had a PR in the pelvic recurrence and continues on the study. In another patient who had liver metastases from colon cancer, a PR was seen in the target liver lesions. This patient developed small bowel obstruction and underwent surgery, and therefore did not have a confirmatory scan at 28 days to verify PR. Seven patients had MRs, as documented by the investigator. Five of these patients had liver metastases from colorectal disease, one had liver metastases from a neuroendocrine tumor, and one had GIST. Because only CR, PR, or SD and not MR were the choices for response on the case record form, a total of 24 patients had the best response of SD reported.
An encouraging aspect of the trial was the length of time some patients were participating in the study, with a median of four cycles given overall. Seven patients participated in the study for at least 12 months, nine patients participated for 6 to 11 months, and seven patients continue to participate in the study. Of these, one patient with a neuroendocrine tumor of the pancreas with liver metastases has been participating in the study for more than 24 months. His status deserves special mention because he presented with severe abdominal pain that was uncontrolled with simple analgesics and a nerve block was planned. Within a few days of commencing PTK/ZK 750 mg bid, the pain completely subsided. Interestingly, during this time his previously controlled hypertension became uncontrolled, and he developed a grade 3 increase in liver ALT and AST. His observations normalized after a short break from PTK/ZK, during which time his pain recurred. An additional antihypertensive agent was introduced and a reduction in PTK/ZK to 500 mg bid was made. The MRI measurements confirmed that he had an MR in the liver lesions and stabilization of the tumor mass in his pancreas. He continued to participate in the study and has received more than 24 cycles of treatment with PTK/ZK.
Patients with colorectal cancer and liver metastases also appeared to do particularly well. Two women with actively progressing liver metastases from colorectal cancer after surgery (including liver resection) and chemotherapy (irinotecan in one patient and oxaliplatin and infused fluorouracil plus leucovorin [FOLFOX] in the other) had stabilization of their disease for 10 and 22 months, respectively. Another interesting occurrence was a patient with marked ascites and peritoneal disease from a primary gastric tumor. Because the VEGF pathway is a potent inducer of vascular permeability,4 we hypothesized that PTK/ZK may be useful in patients with ascites. Clearly, ascites is a difficult site of disease to assess for response. Nevertheless, this patient has had clinically SD not requiring paracentesis and has been receiving PTK/ZK 750 mg bid for more than 10 cycles.
DISCUSSION
When this study was designed, it was considered that the biologically active dose of PTK/ZK would not necessarily be the same as the MTD. Indeed, it was not clear from the preclinical data whether any toxicity would be evident. DLT however, was observed in this trial using PTK/ZK on a continuous basis bid in patients with advanced cancer. The DLT was grade 3 lightheadedness observed at 1,000 mg bid, and to a lesser degree at the lower dose levels. A variety of symptoms accompanied the lightheadedness. In the worst case, ataxia and dysarthria with lightheadedness caused the patients to be bedbound. In the mild cases, dizziness was not at all incapacitating. For the majority of patients who experienced lightheadedness, the symptom subsided during several days, with no dose adjustment of PTK/ZK necessary. The etiology of this adverse event is not clear
it may occur less than 1 hour after ingestion of the drug but usually appears by day 2. Thus, the lightheadedness may be related to early high exposure and will be evaluated further in other studies.
Adverse events associated with PTK/ZK are generally well tolerated at doses 750 mg bid, which is supported by the prolonged duration of treatment of some of our study patients. Exacerbation of pre-existing hypertension in patients with previously well-controlled blood pressure was also observed as an adverse event. The hypertension is easily controlled with standard medication. Hypertension has been observed with all of the oral VEGF tyrosine kinase inhibitors, although to date these findings have only been reported in abstract form. We postulate that this is due to the action of VEGF on the nitric oxide pathway.19 One patient experienced grade 3 neutropenia, and had entered the study with a grade 1 neutropenia. VEGF receptors are present on bone marrow progenitor cells and this event may have been related to PTK/ZK.20
Findings from this study further support the use of DCE-MRI as a biomarker for assessment of biologic activity with antiangiogenic agents. The reduction in MRI Ki was greater in patients with nonprogressive disease compared with those with progressive disease. A reduction in MRI Ki of greater than 40% is associated with a significant increase in likelihood of disease stabilization. The change in DCE-MRI was correlated with PTK/ZK exposure, including AUC, Cmax, and Cmin, and to a lesser extent with oral dose, especially on day 2. Therefore, relationship between AUC and MRI Ki was characterized by an inhibitory Emax model on day 2 and day 28 to explore the PK/PD relationship with DCE-MRI in early treatment and at steady-state with a bid regimen. The change in MRI Ki is consistent with previously reported data in colorectal cancer patients with liver metastases using the once-daily PTK/ZK regimen.17 This sustained reduction in MRI Ki in the range of 40% to 50% up to day 56 was achieved by the majority of patients who received 1,000 mg/d (500 mg bid) or more. Furthermore, statistical analysis indicates that MRI Ki (day 2) is a strong predictive marker for disease stabilization, thus supporting the use of DCE-MRI as a biomarker for early assessment of tumor response.
In a previous publication, Morgan et al17 used DCE-MRI to define the biologically active dose of PTK/ZK
most patients with nonprogressive disease received a single daily dose of 1,000 mg. All but 10 patients in this bid study received total daily doses of 1,000 mg/d. Thus, 33 of the 43 patients were treated at a biologically active dose and only five experienced rapid disease progression. PTK/ZK administered bid produces prolonged periods of disease stabilization and tumor responses with similar frequency as those seen in patients receiving PTK/ZK on a once-daily schedule.17,21-24 In view of the interesting antitumor activity seen in patients with colorectal cancer in both the once-daily and bid dosing studies, PTK/ZK has been studied in combination with oxaliplatin and infused fluorouracil plus leucovorin (FOLFOX) as first-line treatment of patients with advanced colorectal cancer.25
this study, the MTD of PTK/ZK administered is 750 mg bid. The DCE-MRI results suggest that the biologically active dose of PTK/ZK is at least 1,000 mg/d. Pharmacokinetic data from this study show that at equivalent daily doses, drug exposure is comparable with the previous once-daily–dosing study
however, the trough levels are significantly higher with the bid dosing. Whether this will translate into improved efficacy is at this time unknown, and additional phase II studies with bid dosing will be necessary to address this important issue.
Although 750 mg bid is the MTD, low-grade toxicities were observed that could compromise compliance for chronic continuous administration. Given that the pharmacokinetic parameters and DCE-MRI changes both suggest a plateau of relation with dose more than 500 mg bid, it seems appropriate to recommend that future studies incorporate a total daily dose of 1,000 mg to minimize toxicity and thus allow chronic continuous administration. Given the potential to incorporate this agent into future long-term studies, for example as maintenance or adjuvant therapy, it is essential to choose a dose and schedule that achieve biologic activity but minimize the incidence of adverse events. This is the major challenge for the design of phase I studies with new targeted agents, and it is clearly essential to validate the pharmacodynamic end point used in this study, DCE-MRI (combined with pharmacokinetic assessments), in future trials with this and other angiogenesis inhibitors.
Authors' Disclosures of Potential Conflicts of Interest
The following authors or their immediate family members have indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. Employment: Andrea Kay, Novartis
Lucy Lee, Novartis
Eric Masson, Novartis
Dirk Laurent, Schering AG. Consultant/Advisory Role: William P. Steward, Ispen, Novartis, Roche. Stock Ownership: Andrea Kay, Novartis
Eric Masson, Novartis
Dirk Laurent, Schering AG. Honoraria: Anne L. Thomas, Novartis, Roche
Bruno Morgan, Schering AG
William P. Steward, Ispen, Novartis, Roche. For a detailed description of these categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and Disclosures of Potential Conflicts of Interest found in Information for Contributors in the front of each issue.
Acknowledgment
We thank all of the nursing and administrative staff from the oncology trials unit and the MRI radiographic staff from Leicester University Hospitals who have been involved with this study during the last 3 years. We also thank David Lebwohl, Marie Puccio-Pick, and Yu Yun Ho from Novartis Pharmaceuticals and Martina Poethig and Clemens Guenther from Schering AG for their support.
NOTES
Supported by Novartis Pharmaceuticals Corp, East Hanover, NJ, and Schering AG, Berlin, Germany.
Authors' disclosures of potential conflicts of interest are found at the end of this article.
REFERENCES
Folkman J: Anti-angiogenesis: New concept for therapy of solid tumors. Ann Surg 175:409-416, 1972
Ferrara N: Role of vascular endothelial growth in regulation of physiological angiogenesis. Am J Physiol Cell 280:C1358-C1366, 2001
Siemeister G, Martiny-Baron G, Marme D: The pivotal role of VEGF in tumor angiogenesis: Molecular facts and therapeutic opportunities. Cancer Metastasis Rev 17:241-248, 1998
Dvorak HF, Brown LF, Detmar M, et al: Vascular permeability factor/vascular endothelial growth factor, microvascular hyperpermeability, and angiogenesis. Am J Pathol 146:1029-1039, 1995
Shibuya M, Yamaguchi S, Yaname A, et al: Nucleotide sequences and expression of a novel human receptor-type tyrosine kinase gene (flt) closely related to the fms family. Oncogene 5:519-524, 1990
Terman BI, Dougher VM, Carrion ME, et al: Identification of the KDR tyrosine kinase as a receptor for vascular endothelial growth factor. Biochem Biophys Res Commun 187:1579-1586, 1992
Achen MG, Jeltsch M, Kukk E, et al: Vascular endothelial growth factor D (VEGF-D) is a ligand for the tyrosine kinases VEGF receptor 2 (Flk1) and VEGF receptor 3 (Flt4). Proc Natl Acad Sci U S A 95:548-553, 1998
Olofsson B, Pajusola K, Kaipainen A, et al: Vascular endothelial growth factor B, a novel growth factor for endothelial cells. Proc Natl Acad Sci U S A 93:2576-2581, 1996
Olofsson B, Korpelainen E, Pepper MS, et al: Vascular endothelial growth factor B (VEGF-B) binds to VEGF receptor-1 and regulates plasminogen activator activity in endothelial cells. Proc Natl Acad Sci U S A 95:11709-11714, 1998
Joukov V, Kaipainen A, Jeltsch M, et al: Vascular endothelial growth factors VEGF-B and VEGF-C. J Cell Physiol 173:211-215, 1997
Hurwitz H, Fehrenbacher L, Novotny W, et al: Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med 350:2335-2342, 2004
Arteaga CL: Molecular therapeutics: Is one promiscuous drug against multiple targets better than combinations of molecule-specific drugs. Clin Cancer Res 9:1231-1232, 2003
Wood JM, Bold G, Buchdunger E, et al: PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration. Cancer Res 60:2178-2189, 2000
Drevs J, Muller-Driver R, Wittig C, et al: PTK787/ZK 222584, a specific vascular endothelial growth factor-receptor tyrosine kinase inhibitor, affects the anatomy of the tumor vascular bed and the functional vascular properties as detected by dynamic enhanced magnetic resonance imaging. Cancer Res 62:4015-4122, 2002
Moertel CG, Hanley JA: The effect of measuring error on the results of therapeutic trials in advanced cancer. Cancer 38:388-394, 1976
James K, Eisenhauer E, Christian M, et al: Measuring response in solid tumors: Unidimensional versus bidimensional measurement. J Natl Cancer Inst 91:523-528, 1999
Morgan B, Thomas AL, Drevs J, et al: Dynamic contrast-enhanced magnetic resonance imaging as a biomarker for the pharmacological response of PTK787/ZK 222584, an inhibitor of the vascular endothelial growth factor receptor tyrosine kinases, in patients with advanced colorectal cancer and liver metastases: Results from two phase I studies. J Clin Oncol 21:3955-3964, 2003
Larsson HB, Fritz-Hansen T, Rostrup E, et al: Myocardial perfusion modeling using MRI. Magn Reson Med 35:716-726, 1996
Parikh AA, Ellis LM: The vascular endothelial growth factor family and its receptors. Hematol Oncol Clin N Am 18:951-971, 2004
Hattori K, Heissig B, Wu Y, et al: Placental growth factor reconstitutes hematopoiesis by recruiting VEGFR1(+) stem cells from bone-marrow microenvironment. Nat Med 8:841-849, 2002
Conrad C, Friedman H, Reardon D, et al: A phase I/II trial of single-agent PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in patients with recurrent glioblastoma multiforme (GBM). Proc Am Soc Clin Oncol 22:110, 2004 (abstr 1512)
Reardon D, Friedman H, Brada M, et al: A phase I/II trial of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in combination with either temozolomide or lomustine for patients with recurrent glioblastoma multiforme (GBM). Proc Am Soc Clin Oncol 22:110, 2004 (abstr 1513)
Schleucher N, Trarbach T, Junker U, et al: Phase I/II study of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor in combination with FOLFIRI as first-line treatment for patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 22:259, 2004 (abstr 3558)
George D, Michaelson D, Oh WK, et al: Phase I study of PTK787/ZK 222584 (PTK/ZK) in metastatic renal cell carcinoma. Proc Am Soc Clin Oncol 22:385, 2003 (abstr 1548)
Steward WP, Thomas AL, Morgan B, et al: Expanded phase I/II study of PTK787/ZK 222584 (PTK/ZK), a novel, oral angiogenesis inhibitor, in combination with FOLFOX4 as first-line treatment for patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 22:259, 2004 (abstr 3556)(Anne L. Thomas, Bruno Mor)