Somer, Robert A.

CRA1002 The full, final text of this abstract will be available at abstract.asco.org at 12:01 AM (EDT) on Monday, June 4, 2012, and in the Annual Meeting Proceedings online supplement to the June 20, 2012, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Monday edition of ASCO Daily News.

CRA1002 Background: Weekly P is superior to q 3 week (wk) dosing, and adding B improves progression free survival (PFS) (E2100). Ix is a potent epothilone that can be effective after microtubule inhibitor resistance. NP is a novel albumin-bound formulation of P with promising activity in the first-line MBC setting. In this phase III trial, the efficacy of weekly Ix or NP is compared to P, in combination with B in patients (pts) with chemotherapy (CTX) naïve MBC. Toxicity including >Grade 2 sensory neuropathy (SN) is compared to P. Methods: Pts were randomized 1:1:1 to receive P (90 mg/m2), Ix (16 mg/m2) or NP (150 mg/m2) on a 3 wk on, 1 wk off schedule, stratified by prior adjuvant taxane use and hormone receptor status. B was initially given to all pts, but became optional in 3/2011 and was added to stratification. The primary end point of PFS is defined as time from randomization to progression or all-cause death. With a target N=900 pts, the study was powered to detect a hazard ratio (HR) of 1.36 (median PFS 10 vs 13.6 mos). Eligibility included no prior CTX for MBC, >12 mos from adjuvant P and measurable disease. Results: 799 pts were enrolled between 11/08-11/11 (283 to P, 271 to NP, 245 to Ix); 98% received B. 72% had ER+ disease, 44% received adjuvant P. At the 1st interim analysis (165 events) the comparison of Ix to P crossed the futility boundary (FB) and accrual to Ix was closed. At the 2nd interim analysis (236 events), NP to P crossed the FB and the study was closed on 11/30/11. Median PFS was 10.4, 9.6 and 7.6 mos for P, NP and Ix, with HRs (95% CIs) of 0.94 (0.73-1.22) and 0.66 (0.51-0.84) for P to NP and Ix respectively. Grade 2+ SN was 48% for NP, 44% for Ix and 37% for P; Grade 3+ hematologic toxicity was 49% for NP, 20% for Ix, and 12% for P. Conclusions: In pts with CTX naive MBC, both NP and Ix are highly unlikely to be superior to P for PFS (when all are combined with B), and in combination with B, weekly P is the better tolerated drug. Toxicity including SN was greater in each experimental arm compared to P. Updated data will be presented, and correlative studies will be reported at a future date.