CDK4/6 inhibitors and antiprogestins: therapeutic combination in breast cancer experimental models with high levels of progesterone receptor isoform A

Abstract

Luminal breast cancers are susceptible to an endocrine therapy. Palbociclib (PALBO), a CDK 4/6 inhibitor, is cur-rently used in combination with endocrine therapy to treat advanced hormone receptor-positive breast cancer (BC). However, with time patients acquire resistance. Therefore, alternative therapies are required to reduce BC mortality. We have recently reported that BC patients with tumors expressing higher levels of isoform A of the progesterone re-ceptor (PRA) than isoform B (PRB) may benefit from an an -tiprogestin treatment.