Theodore F. Lagattuta

Phase II Study of Imatinib Mesylate Plus Hydroxyurea in Adults With Recurrent Glioblastoma Multiforme

PURPOSE We performed a phase II study to evaluate the combination of imatinib mesylate, an adenosine triphosphate mimetic, tyrosine kinase inhibitor, plus hydroxyurea, a ribonucleotide reductase inhibitor, in patients with recurrent glioblastoma multiforme (GBM). PATIENTS AND METHODS Patients with GBM at any recurrence received imatinib mesylate plus hydroxyurea (500 mg twice a day) orally on a continuous, daily schedule. The imatinib mesylate dose was 500 mg twice a day for patients on enzyme-inducing antiepileptic drugs (EIAEDs) and 400 mg once a day for those not on EIAEDs. Assessments were performed every 28 days. The primary end point was 6-month progression-free survival (PFS). RESULTS Thirty-three patients enrolled with progressive disease after prior radiotherapy and at least temozolomide-based chemotherapy. With a median follow-up of 58 weeks, 27% of patients were progression-free at 6 months, and the median PFS was 14.4 weeks. Three patients (9%) achieved radiographic response, and 14 (42%) achieved stable disease. Cox regression analysis identified concurrent EIAED use and no more than one prior progression as independent positive prognostic factors of PFS. The most common toxicities included grade 3 neutropenia (16%), thrombocytopenia (6%), and edema (6%). There were no grade 4 or 5 events. Concurrent EIAED use lowered imatinib mesylate exposure. Imatinib mesylate clearance was decreased at day 28 compared with day 1 in all patients, suggesting an effect of hydroxyurea. CONCLUSION Imatinib mesylate plus hydroxyurea is well tolerated and associated with durable antitumor activity in some patients with recurrent GBM.

Effect of St John's wort on imatinib mesylate pharmacokinetics.

Imatinib is a potent inhibitor of the Bcr‐Abl and c‐kit tyrosine kinases and is approved for the treatment of Philadelphia chromosome–positive chronic myelogenous leukemia and gastrointestinal stromal tumors. Because imatinib is predominantly metabolized by cytochrome P450 (CYP) 3A4, its pharmacokinetics may be altered when it is coadministered with drugs or herbs (eg, St Johns wort) that modulate CYP3A4 activity. Thus we examined the effects of St Johns wort on imatinib pharmacokinetics.

Phase I and Pharmacokinetic Study of Vorinostat, A Histone Deacetylase Inhibitor, in Combination with Carboplatin and Paclitaxel for Advanced Solid Malignancies

Purpose: The primary objective of this study was to determine the recommended phase II doses of the novel histone deacetylase inhibitor vorinostat when administered in combination with carboplatin and paclitaxel. Experimental Design: Patients (N = 28) with advanced solid malignancies were treated with vorinostat, administered orally once daily for 2 weeks or twice daily for 1 week, every 3 weeks. Carboplatin and paclitaxel were administered i.v. once every 3 weeks. Doses of vorinostat and paclitaxel were escalated in sequential cohorts of three patients. The pharmacokinetics of vorinostat, its metabolites, and paclitaxel were characterized. Results: Vorinostat was administered safely up to 400 mg qd or 300 mg bd with carboplatin and paclitaxel. Two of 12 patients at the 400 mg qd schedule experienced dose-limiting toxicities of grade 3 emesis and grade 4 neutropenia with fever. Non–dose-limiting toxicity included nausea, diarrhea, fatigue, neuropathy, thrombocytopenia, and anemia. Of 25 patients evaluable for response, partial responses occurred in 11 (10 non–small cell lung cancer and 1 head and neck cancer) and stable disease occurred in 7. Vorinostat pharmacokinetics were linear over the dose range studied. Vorinostat area under the concentration versus time curve and half-life increased when vorinostat was coadministered with carboplatin and paclitaxel, but vorinostat did not alter paclitaxel pharmacokinetics. Conclusions: Both schedules of vorinostat (400 mg oral qd × 14 days or 300 mg bd × 7 days) were tolerated well in combination with carboplatin (area under the concentration versus time curve = 6 mg/mL × min) and paclitaxel (200 mg/m2). Encouraging anticancer activity was noted in patients with previously untreated non–small cell lung cancer.

Phase I and Pharmacokinetic Study of Imatinib Mesylate in Patients With Advanced Malignancies and Varying Degrees of Renal Dysfunction : A Study by the National Cancer Institute Organ Dysfunction Working Group

PURPOSE This study was undertaken to determine the safety, dose-limiting toxicities (DLT), maximum-tolerated dose (MTD), and pharmacokinetics of imatinib in cancer patients with renal impairment and to develop dosing guidelines for imatinib in such patients. PATIENTS AND METHODS Sixty adult patients with advanced solid tumors and varying renal function (normal, creatinine clearance [CrCL] >or= 60 mL/min; mild dysfunction, CrCL 40 to 59 mL/min; moderate dysfunction, CrCL 20 to 39 mL/min; and severe dysfunction, CrCL < 20 mL/min) received daily imatinib doses of 100 to 800 mg. Treatment cycles were 28 days long. RESULTS The MTD was not reached for any group. DLTs occurred in two mild group patients (600 and 800 mg) and two moderate group patients (200 and 600 mg). Serious adverse events (SAEs) were more common in the renal dysfunction groups than in the normal group (P = .0096). There was no correlation between dose and SAEs in any group. No responses were observed. Several patients had prolonged stable disease. Imatinib exposure, expressed as dose-normalized imatinib area under the curve, was significantly greater in the mild and moderate groups than in the normal group. There was a positive correlation between serum alpha-1 acid glycoprotein (AGP) concentration and plasma imatinib, and an inverse correlation between plasma AGP concentration and imatinib clearance. Urinary excretion accounted for 3% to 5% of the daily imatinib dose. CONCLUSION Daily imatinib doses up to 800 or 600 mg were well tolerated by patients with mild and moderate renal dysfunction, respectively, despite their having increased imatinib exposure.

Phase I pharmacokinetic study of the vascular endothelial growth factor receptor tyrosine kinase inhibitor vatalanib (PTK787) plus imatinib and hydroxyurea for malignant glioma

This study determined the maximum tolerated dose (MTD) and dose‐limiting toxicities (DLT) of the oral vascular endothelial growth factor receptor (VEGFR) inhibitor, vatalanib, when administered with imatinib and hydroxyurea on a continuous daily schedule among recurrent malignant glioma patients.

A Phase I Study of 17-Allylamino-17-Demethoxygeldanamycin Combined with Paclitaxel in Patients with Advanced Solid Malignancies

Background: 17-Allylamino-17-demethoxygeldanamycin (17-AAG) inhibits heat shock protein 90, promotes degradation of oncoproteins, and exhibits synergy with paclitaxel in vitro. We conducted a phase I study in patients with advanced malignancies to determine the recommended phase II dose of the combination of 17-AAG and paclitaxel. Methods: Patients with advanced solid malignancies that were refractory to proven therapy or without any standard treatment were included. 17-AAG (80-225 mg/m2) was given on days 1, 4, 8, 11, 15, and 18 of each 4-week cycle to sequential cohorts of patients. Paclitaxel (80-100 mg/m2) was administered on days 1, 8, and 15. Pharmacokinetic studies were conducted during cycle 1. Results: Twenty-five patients were accrued to five dose levels. The median number of cycles was 2. Chest pain (grade 3), myalgia (grade 3), and fatigue (grade 3) were dose-limiting toxicities at dose level 4 (225 mg/m2 17-AAG and 80 mg/m2 paclitaxel). None of the six patients treated at dose level 3 with 17-AAG (175 mg/m2) and paclitaxel (80 mg/m2) experienced dose-limiting toxicity. Disease stabilization was noted in six patients, but there were no partial or complete responses. The ratio of paclitaxel area under the concentration to time curve when given alone versus in combination with 17-AAG was 0.97 ± 0.20. The ratio of end-of-infusion concentration of 17-AAG (alone versus in combination with paclitaxel) was 1.14 ± 0.51. Conclusions: The recommended phase II dose of twice-weekly 17-AAG (175 mg/m2) and weekly paclitaxel (80 mg/m2/wk) was tolerated well. There was no evidence of drug-drug pharmacokinetic interactions.

Safety and pharmacokinetics of dose-intensive imatinib mesylate plus temozolomide: Phase 1 trial in adults with malignant glioma

We determined the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of imatinib mesylate, an inhibitor of the receptor tyrosine kinases platelet-derived growth factor receptor (PDGFR), the proto-oncogene product c-kit, and the fusion protein Bcr-Abl, when administered for 8 days in combination with temozolomide (TMZ) to malignant glioma (MG) patients. MG patients who had not failed prior TMZ were eligible to receive TMZ at a dose of 150-200 mg/m(2) per day on days 4-8 plus imatinib mesylate administered orally on days 1-8 of each 4-week cycle. Patients were stratified based on concurrent administration of CYP3A4-inducing antiepileptic drugs (EIAEDs). The imatinib dose was escalated in successive cohorts of patients independently for each stratum. Imatinib, at doses ranging from 400 mg to 1,200 mg, was administered with TMZ to 65 patients: 52 (80%) with glioblastoma multiforme (GBM) and 13 (20%) with grade III MG. At enrollment, 34 patients (52%) had stable disease, and 33 (48%) had progressive disease; 30 patients (46%) were on EIAEDs. The MTD of imatinib for patients concurrently receiving or not receiving EIAEDs was 1,000 mg. DLTs were hematologic, gastrointestinal, renal, and hepatic. Pharmacokinetic analyses revealed lowered exposures and enhanced clearance among patients on EIAEDs. Among GBM patients with stable disease at enrollment (n=28), the median progression-free and overall survival times were 41.7 and 56.1 weeks, respectively. Imatinib doses up to 1,000 mg/day for 8 consecutive days are well tolerated when combined with standard TMZ dosing for MG patients. A subsequent phase 2 study is required to further evaluate the efficacy of this regimen for this patient population.

Phase I and Pharmacokinetic Study of Imatinib Mesylate (Gleevec) and Gemcitabine in Patients with Refractory Solid Tumors

Purpose: Preclinical data shows improvements in response for the combination of imatinib mesylate (IM, Gleevec) and gemcitabine (GEM) therapy compared with GEM alone. Our goals were to determine the maximum tolerated dose of GEM and IM in combination, the pharmacokinetics of GEM in the absence and in the presence of IM, and IM pharmacokinetics in this combination. Patients and Methods: Patients with refractory malignancy, intact intestinal absorption, measurable/evaluable disease, adequate organ function, Eastern Cooperative Oncology Group PS 0-2, and signed informed consent were eligible. Initially, treatment consisted of 600 mg/m2 of GEM (10 mg/m2/min) on days 1, 8, and 15, and 300 mg of IM daily every 28 days. Due to excessive toxicity, the schedule was altered to IM on days 1 to 5 and 8 to 12, and GEM on days 3 and 10 every 21 days. Two final cohorts received IM on days 1 to 5, 8 to 12, and 15 to 19. Results: Fifty-four patients were treated. IM and GEM given daily at 500 to 600 mg/m2 on days 1, 8, and 15 produced frequent dose-limiting toxicities. With the modified scheduling, GEM given at 1,500 mg/m2/150 min was deliverable, along with 400 mg of IM, without dose-limiting toxicities. Three partial (laryngeal, renal, and mesothelioma) and two minor (renal and pancreatic) responses were noted at GEM doses of 450 to 1,500 mg/m2. Stable disease >24 weeks was seen in 17 patients. CA19-9 in 7 of 10 patients with pancreatic cancer was reduced by ∼90%. IM did not significantly alter GEM pharmacokinetics. Conclusion: The addition of intermittently dosed IM to GEM at low to full dose was associated with broad antitumor activity and little increase in toxicity.

Disposition of Imatinib and Its Metabolite CGP74588 in a Patient with Chronic Myelogenous Leukemia and Short‐Bowel Syndrome

Imatinib mesylate, licensed to treat chronic myelogenous leukemia and gastrointestinal stromal tumors, is metabolized by means of cytochrome P450 3A and excreted primarily in the bile. Although the bioavailability of imatinib mesylate is more than 97%, the exact gastrointestinal site of its absorption is unknown. Liquid chromatography‐mass spectrometry was used to quantitate imatinib and its metabolite CGP74588 in the plasma and jejunostomy output of a patient with newly diagnosed chronic myelogenous leukemia. She had previously lost most of her small bowel and all of her colon as a result of mesenteric artery thrombosis and radiation‐induced colitis and/or proctitis. Imatinib pharmacokinetics in plasma indicated that approximately 20% of the patients 400‐mg dose was absorbed. The jejunostomy output contained 338 mg of imatinib, which was consistent with 320 mg of a nonabsorbed dose plus approximately 23% of the absorbed dose being excreted unchanged in the bile. These data indicate the importance of considering gastrointestinal anatomic abnormalities or disease states when oral imatinib is dosed.

Biliary Excretion of Imatinib Mesylate and Its Metabolite CGP 74588 in Humans

Imatinib mesylate, licensed to treat chronic myelogenous leukemia and gastrointestinal stromal tumors, is metabolized by cytochrome P450 3A and undergoes little renal excretion, but its biliary excretion by humans is uncharacterized. Liquid chromatography–mass spectrometry was used to quantitate imatinib and its metabolite CGP 74588 in the bile of two patients with biliary stents; the ratio of imatinib:CGP 74588 in each was approximately 9:1. In the first patient, who was receiving long‐term therapy with imatinib 400 mg/day and had normal liver function tests, biliary imatinib accounted for 17.7% of the daily dose and CGP 74588 accounted for 2.1%. In the second patient, who had elevated liver function tests and was studied after his first dose of imatinib 300 mg, biliary imatinib accounted for only 1.8% of the daily dose and CGP 74588 accounted for 0.2%. These data show both the qualitative similarities and the quantitative variability in biliary excretion of imatinib and its principal metabolite.