Phase I trial of poly-L-glutamate camptothecin (CT-2106) administered weekly in patients with advanced solid malignancies.

PURPOSE: CT-2106 is a 20(S)-camptothecin poly-L-glutamate conjugate. This linkage stabilizes the active lactone form of camptothecin and enhances aqueous solubility. In addition, poly-L-glutamate is postulated to increase tumor delivery of the active compound through enhanced permeability and retention effect in tumor. We studied a weekly schedule of CT-2106 in patients with refractory solid tumor malignancies. EXPERIMENTAL DESIGN: CT-2106 was infused (10 min i.v. infusion) on days 1, 8, and 15 of each 28-day cycle. Plasma and urine were analyzed for total and unconjugated camptothecin by high-performance liquid chromatography equipped with a fluorescence detector. Toxicity and response assessments were done with Common Toxicity Criteria for Adverse Events version 3 and Response Evaluation Criteria in Solid Tumors, respectively. RESULTS: Twenty-six patients were enrolled. Median age was 58 years (range, 36-83) and median number of doses was 6 (range, 1-9). The most frequent tumor type (50%) was melanoma. Dose limiting toxicities were thrombocytopenia and fatigue. A weekly dose of 25 mg/m2 given every 3 of 4 weeks was the maximum tolerated dose. The majority of grade 3 and 4 toxicities were hematologic. The pharmacokinetic profile of conjugated and unconjugated camptothecin showed a polyexponential decline with similar terminal half life (t1/2 range was 44-63 and 31-48 h for conjugated and unconjugated, respectively). Pharmacokinetics of conjugated and unconjugated camptothecin were dose and time independent in the tested dose range. Urinary excretion of conjugated and unconjugated camptothecin accounted for about 30% and 4% of the administered dose, respectively. CONCLUSIONS: CT-2106 has a more manageable toxicity profile compared with unconjugated camptothecin. The maximum tolerated dose is 25 mg/m2 weekly given 3 of 4 weeks. This compound results in prolonged release of unconjugated camptothecin.

Pilot study of PD-0325901 in previously treated patients with advanced melanoma, breast cancer, and colon cancer.

PURPOSE: To assess further the tolerability and preliminary antitumor activity of PD-0325901 in previously treated patients with advanced melanoma, breast cancer, and colon cancer. METHODS: This pilot study evaluated PD-0325901 on an intermittent dosing schedule. PD-0325901 was administered orally at 20 mg twice daily (BID) for 21 consecutive days followed by 7 days of no treatment. This dose was not well tolerated and consequently changed to 15 mg BID. RESULTS: Between October and December 2005, 13 patients with metastatic measurable disease were entered into the study (seven melanoma, three breast cancer, and three colon cancer). All patients had received prior systemic therapy and were treated with a total of 61 cycles of PD-0325901 (nine received an initial dose of 20 mg BID, four an initial dose of 15 mg BID). The study was terminated early because of an unexpected high incidence of musculoskeletal and neurological adverse events, including gait disturbance, memory impairment, confusion, mental status changes, mild to moderate visual disturbances, and muscular weakness including neck weakness ("dropped-head syndrome"). Other common toxicities were diarrhea, acneiform rash, fatigue, and nausea. There was no significant hematologic toxicity, and chemistry abnormalities were rare. One patient achieved a confirmed complete response, and five patients had stable disease. CONCLUSIONS: PD-0325901 can cause significant musculoskeletal, neurological, and ocular toxicity at doses ≥ 15 mg BID. Future studies with adaptive designs might evaluate doses ≤ 10 mg BID in tumor types with a high incidence of Ras and Raf mutations. ClinicalTrials.gov identifier NCT00147550.