Phase I and pharmacokinetic study of temozolomide on a daily-for-5-days schedule in patients with advanced solid malignancies.

PURPOSE: To determine the principal toxicities, characterize the pharmacokinetics (PKs) and pharmacodynamics (PDs) of temozolomide (TMZ) on a daily-for-5-days schedule, and recommend a dose for subsequent disease-directed studies in both minimally pretreated (MP) and heavily pretreated (HP) patients. PATIENTS AND METHODS: Patients received TMZ as a single oral dose daily for 5 consecutive days every 28 days. TMZ doses were escalated from 100 to 150, and 150 to 200 mg/m(2)/d in separate cohorts of MP and HP patients. PK plasma was sampled on days 1 and 5. TMZ concentrations were analyzed and pertinent PK parameters were related to the principal toxicities of TMZ in PD analyses. RESULTS: Twenty-four patients were treated with 85 courses of TMZ. Thrombocytopenia and neutropenia were the principal dose-limiting toxicities (DLTs) of TMZ on this schedule. The cumulative rate of severe myelosuppressive effects was unacceptably high at TMZ doses exceeding 150 mg/m(2)/d in both MP and HP patients. TMZ was absorbed rapidly with maximum concentrations achieved in 0.90 hours, on average, and elimination was rapid, with a half-life and systemic clearance rate (Cl(S/F)) averaging 1.8 hours and 115 mL/min/m(2), respectively. When clearance was normalized to body-surface area (BSA), interpatient variability in Cl(S/F) was reduced from 20% to 13% on day 1 and from 16% to 10% on day 5. Patients who experienced DLT had significantly higher maximum drug concentration( )(median 16 v 9.5 microg/mL, P =. 0084) and area under the concentration-time curve (median 36 v 23 microg-h/mL, P =.0019) values on day 5. CONCLUSION: Prior myelosuppressive therapy was not a determinant of toxicity. TMZ 150 mg/m(2)/d administered as a single oral dose daily for 5 days every 4 weeks is well tolerated by MP and HP patients, with higher doses resulting in unacceptably high rates of severe hematologic toxicity. TMZ doses should be individualized according to BSA rather than use of a prespecified oral dose for all individuals. TMZ is an optimal agent to develop in combination with other cytotoxic, biologic, and targeted therapeutics for patients with relevant malignancies.

Phase I trial of paclitaxel and gemcitabine administered every two weeks in patients with refractory solid tumors.

PURPOSE: Paclitaxel and gemcitabine possess broad spectra of clinical activity, distinct mechanisms of cytotoxicity, and are differentially affected by mutations in cell-cycle regulatory proteins, such as bcl-2. This phase I trial was designed to identify the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of paclitaxel and gemcitabine when both drugs were given together on a once-every-two-week schedule in patients with solid tumors. PATIENTS AND METHODS: A total of 37 patients were treated at nine different dose levels ranging from paclitaxel 75-175 mg/m2 administered over three hours followed by gemcitabinc 1500-3500 mg/m2 administered over 30-60 minutes. Both drugs were administered on day 1 of a 14-day cycle. Dose escalation was performed in a stepwise manner in which the dose of one drug was escalated while the dose of the other drug was kept constant. RESULTS: Dose limiting toxicity (DLT) was observed at dose level 9: paclitaxel 175 mg/m2 and gemcitabine 3500 mg/m2 in the form of grade 4 neutropenia lasting for > or = 5 days (one patient) and grade 3 elevation of alanine aminotransferase (AST/SGPT) (one patient). An analysis of delivered dose intensity (DI) over the first three cycles revealed that higher dosages of both drugs were delivered at dose level 7, paclitaxel 150 mg/m2 and gemcitabine 3000 mg/m2 dose level, than at the MTD, dose level 8, paclitaxel 150 mg/m2 and gemcitabine 3500 mg/m2. Partial responses were confirmed in two patients with transitional cell carcinoma (one of the bladder, one of the renal pelvis) and in one patient with adenocarcinoma of unknown primary. CONCLUSIONS: Paclitaxel and gemcitabine is a promising drug combination that can be administered safely and repetitively on an every-other-week schedule. Using this drug administration schedule, the recommended phase II dose is paclitaxel 150 mg/m2 and gemcitabine 3000 mg/m2.