A phase I study of prolonged ambulatory infusion carboplatin with oral etoposide showing activity in prostate cancer

Abstract

Purpose: This phase I study aimed to establish the dose for phase II trials of a dose-intense outpatient regimen of ambulatory carboplatin and oral etoposide. Patients and Methods: Cohorts of three patients received escalating doses of carboplatin 15, 20, and 23 mg/m²/day as a 3-week continuous ambulatory infusion with oral etoposide initially at 50 mg/day. Patients entered had prostate, colon, head and neck, breast, unknown primary cancers and mesothelioma. Results: At 23 mg/m² of carboplatin, two patients had WHO grade 3 lethargy and myelosuppression, which were the dose-limiting toxicities. Six patients were entered at the dose recommended for phase II studies, carboplatin 20 mg/m²/day and etoposide 50 mg/day for 21 days repeated every 6 weeks. This was well tolerated except for one patient with multiple bone metastases from prostate cancer experiencing grade 4 myelosuppression and a single patient with grade 3 constipation. Seven patients with hormone-resistant prostate cancer were entered into the study, one at 15 mg/m², four at 20 mg/m² and two at 23 mg/m² of carboplatin, and received a median of four cycles of treatment. The only responses were seen in prostate cancer where there were two partial responses in patients with soft tissue predominant disease. Five patients who could be evaluated with initially elevated PSA exhibited falls of ≥50% after receiving the chemotherapy. All but one patient with prostate cancer experienced significant reduction in pain levels. The median time to progression of the patients with prostate cancer was 4 months. Conclusions: Ambulatory infusion carboplatin and oral etoposide is a tolerable dose- intense outpatient regimen which warrants further testing in phase II trials including hormone-resistant prostate cancer.