Sequential and intermittent docetaxel (D) and imatinib (Im) in hormone-refractory prostate cancer patients (NYU 04–47)

Abstract

e16108 Background: Platelet-derived growth factor is frequently expressed in advanced prostate cancer (PC) lesions where it supports PC cell growth and neo-angiogenesis. Im. is a PDGF inhibitor that blocks cell cycle in G1-S due to MEK/erk inhibition. D blocks cell cycle progression in G2-M. Sequential block of the cell cycle progression in G2-M followed by G1-S may increase anti-tumor responses. The phase II study dose of sequential D on day 1 and Im started 24–36h later given daily for 14 d was established in a previous phase I. Methods: Eligibility: at least 2 prior hormone manipulations and up to one prior chemotherapy, PSA>5ng/ml, ECOG PS 0–2. Treatment schedule: D 70mg/m2 day 1 followed 24–36 hours later by Im 600mg PO daily × 14 days. Cycles were repeated every 21d until toxicity or progression. Pegfilgrastim was given each cycle for neutropenia prevention. A two steps design was planned to assess activity (PSA decline >50% and/or measurable or symptomatic response) and tolerance including interim analysis to determine if 37 patients (pts) should be enrolled. Results: Of 15 pts enrolled, 13 had metastasis and 5(33%) received prior chemotherapy. There were 98 cycles of trial therapy administered and 9 events (PSA or bone progression) registered at the time of analysis. Median baseline PSA 73,5ng/ml (2.1–1954.3). Median follow-up estimated by inverse Kaplan Meier: 308 days (CI95%, 133–482). Median of cycles administrated 6 (1–12). PSA decline >50% observed in 7/15pts (46.67%) of which 3 was >80% (20%). PSA decline <50%, observed in 6/15(40%). 2/15(15.3%) were non-responders. Pain scores improved in all symptomatic pts. Median duration of response was 162 days (42- 281). Estimated median progression free survival by Kaplan-Meier was 155 days (CI95%, 80–339). Toxicity: there was G1–2 fatigue, anorexia, weight change in 66% pts; nausea, vomiting, taste changes in 66% pts, anemia in 46% and neuropathy in 46% pts. G3 fatigue in 2 pts, neuropathy and CHF in 1 pt. No G4 toxicities were observed. Conclusions: Sequential and intermittent D every 21 days and Im for 14 days is tolerable and active by PSA decline and symptomatic improvement. Compared to previous report with weekly D and continuous Im, this alternative schedule appears to have similar activity with better tolerance. [Table: see text]