Survival results with AP23573, a novel mTOR inhibitor, in patients (pts) with advanced soft tissue or bone sarcomas: Update of phase II trial

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Background: AP23573 is an mTOR inhibitor that has demonstrated single-agent activity in a broad range of sarcoma tumor types in phase I phase II trials. Overall survival (OS) was monitored to characterize OS in the treated population and in the subset of patients who achieved a clinical benefit response (CBR). Methods: Pts with advanced sarcomas, with no restrictions on prior therapies, were enrolled into 4 cohorts based on histologic subtype, in a phase 2, Simon's 2-stage trial. AP23573 (12.5 mg, i.v.) was administered daily × 5 every 2 wks. Efficacy was assessed using RECIST, with CBR defined as a complete or partial response or stable disease for at least 16 wks duration. OS was defined as the time from the first dose of AP23573 to the date of death from any cause. Kaplan-Meier estimates of the survival times of the population were calculated with OS time censored at the last date the pt was known to be alive when the confirmation of death is absent or unknown. Patients are continuing to be followed for OS in this ongoing trial. Results: 212 pts (105 M/107 F; median age, 50.6 yrs ([17–79 yrs]) were treated. Most pts (79%) had received =2 prior treatments, and over 90% of pts had disease progression at time of enrollment. The overall CBR rate was 29%, including 5 PRs (4 bone sarcoma, 1 MFH). The median OS was 40.1 wks for the entire study population. In the subset of patients achieving CBRs the median time to OS was 67.6 wks, suggesting that achievement of CBR, which is a measure of tumor control, correlates with extending OS. Conclusions: AP23573 exhibits single-agent activity in pts with advanced sarcomas as demonstrated by the CBR rate as a primary efficacy endpoint. The results of the OS analysis suggest that achieving a CBR in this pt population can result in prolonged survival. The consistency of this finding should be further examined with other pt factors that are also hypothesized to correlate for survival in this pt population.

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