A Novel Combination Treatment Targeting BCL-XL and MCL1 for KRAS/BRAF-mutated and BCL2L1-amplified Colorectal Cancers.

Colorectal cancer is the third most commonly diagnosed cancer in the world, and exhibits heterogeneous characteristics in terms of genomic alterations, expression signature, and drug responsiveness. Although there have been considerable efforts to classify this disease based on high-throughput sequencing techniques, targeted treatments for specific subgroups have been limited. KRAS and BRAF mutations are prevalent genetic alterations in colorectal cancers, and patients with mutations in either of these genes have a worse prognosis and are resistant to anti-EGFR treatments. In this study, we have found that a subgroup of colorectal cancers, defined by having either KRAS or BRAF (KRAS/BRAF) mutations and BCL2L1 (encoding BCL-XL) amplification, can be effectively targeted by simultaneous inhibition of BCL-XL (with ABT-263) and MCL1 (with YM-155). This combination treatment of ABT-263 and YM-155 was shown to have a synergistic effect in vitro as well as in in vivo patient-derived xenograft models. Our data suggest that combined inhibition of BCL-XL and MCL1 provides a promising treatment strategy for this genomically defined colorectal cancer subgroup. Mol Cancer Ther; 16(10); 2178-90. ©2017 AACR. ©2017 American Association for Cancer Research.