Results of the X-PECT study: A phase III randomized double-blind, placebo-controlled study of perifosine plus capecitabine (P-CAP) versus placebo plus capecitabine (CAP) in patients (pts) with refractory metastatic colorectal cancer (mCRC).

Abstract

LBA3501 Background: Perifosine (P) is an oral, synthetic alkylphospholipid that inhibits or modifies signal transduction pathways including AKT, NFkB and JNK. A randomized phase II study examined P-CAP vs. CAP in pts with 2nd or 3rd line mCRC. This study showed improvement in mTTP (HR 0.254 [0.117, 0.555]) and mOS (HR 0.370 [0.180,0.763]). Based on these results, a randomized phase III study of P-CAP vs. CAP with a primary endpoint of overall survival (OS) in pts with refractory mCRC was initiated. Methods: The study was a prospective, randomized, double-blind, placebo-controlled randomized phase III trial. Eligible pts had mCRC which was refractory to all standard therapies. Pts randomized 1:1 to Arm A = P-CAP (P 50 mg PO QD + CAP 1000 mg/m2PO BID d1-14) or Arm B = CAP (placebo + CAP 1000 mg/m2 PO BID d 1-14). Cycles were 21 days. Baseline tumor block collection and a biomarker cohort of pts with pre- and on-treatment tumor and blood samples were performed. Results: Between 3/31/10 and 8/12/11, 468 pts were randomized, 234 pts were in each arm. Baseline demographics were balanced between the arms: age < 65y (A: 65%, B: 58.5%), male (A: 57.7%, B: 53.0%), ECOG PS 0 (A: 39.7%, B: 39.7%), K-ras mutant (A: 50.4%, B: 51.3%), and median number of prior therapies (A: 4, B: 4). As of 3/19/12, median follow up was 6.6 months. Median overall survival: Arm A = 6.4 mo, Arm B = 6.8 mo, HR 1.111 [0.905,1.365], p = 0.315. Median overall survival for K-ras WT pts: Arm A = 6.6 mo, Arm B = 6.8 mo, HR 1.020 [0.763,1.365], p = 0.894; K-ras mutant pts: Arm A = 5.4 mo, Arm B = 6.9 mo HR 1.192 [0.890,1.596], p = 0.238. Conclusions: Despite promising randomized phase II data, this phase III study shows no benefit in overall survival adding perifosine to capecitabine in the refractory colorectal cancer setting. Response rate, progression free survival, and safety data will be presented. Biomarker analysis is pending to see if subgroups of patients may have potential benefit.