Phase Ii Clinical Activity And Tolerability Of The Smac- Mimetic Birinapant (Tl32711) Plus Irinotecan In Irinotecanrelapsed/ Refractory Metastatic Colorectal Cancer

3621 Background: Birinapant (B) is a SMAC-mimetic that inhibits IAPs and has potent preclinical anti-tumor synergy combined with TNFa-inducing chemotherapies [i.e irinotecan (I)]. B and I combination is well-tolerated and has encouraging activity in a phase 1 study. This study tested B+I with an ascending dose strategy (ADS) of B to mitigate Bell’s palsy (BP) risk, an unusual and reversible side effect of SMAC mimetics. Methods: I at 350mg/m2 IV q3weeks was administered with B weekly (2 of 3 weeks). The dose of B was titrated incrementally during Cycle 1: C1D1 at 5.6mg/m2 and C1D8 at 11mg/m2 for ADS. For Cycle 2 (C2) and ongoing treatment, the B dose was 22mg/m2 or 35mg/m2, which were the MTD and DLT (BP) dose levels when combined with I from the Ph 1 study. Safety and clinical activity for KRAS mutant (KRAS-MT) and wild-type (KRAS-WT) were assessed in 3 cohorts: (1) at 22mg/m2 for CRC KRAS MT; (2) 22mg/m2 for CRC KRAS WT; (3) 35mg/m2 for CRC KRAS MT. Results: 51 patients (pts) with CRC had a median numbe...