Priming BCL-2 to kill: the combination therapy of tamoxifen and ABT-199 in ER+ breast cancer

The B-cell lymphoma/leukemia 2 protein (BCL-2) may help many types of cancers to evade cell death. However, identifying exactly where this is the case is a challenge. ABT-199 is a small molecule that selectively inhibits BCL-2, which is currently in clinical trials in lymphoid malignancies. While inhibiting BCL-2 by itself can cause cell death in hematopoietic tumors, single-agent activity is harder to observe in solid tumors. Combining ABT-199 with tamoxifen, the standard endocrine therapy for estrogen receptor-positive breast cancers, 85% of which have BCL-2 expression, represents a new strategy to prime cancer cells for apoptosis and elicit better cancer cell death responses.