PIM kinases in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) lacks estrogen, progesterone, and HER2 receptor expression. It accounts for roughly 15 percent of breast cancers but a disproportionate share of breast-cancer deaths because it is aggressive, often presents young, and responds poorly to existing targeted therapies.

Survey of PIM family expression in TNBC tumors revealed that PIM1 and PIM2 are markedly elevated. The lab tested causality genetically using the MMTV-PyMT transgenic model — a standard breast cancer model with reliable primary-tumor and lung-metastasis kinetics. PIM1 and PIM2 deletion in this background blocks primary tumor growth and prevents metastasis.

Pharmacologically, the same PIM1 inhibitor advanced for myelofibrosis (TP-3654, now Nuvisertib) is active against TNBC: it reduces TNBC cell growth in vitro, overcomes resistance to standard chemotherapeutic agents (docetaxel, doxorubicin, carboplatin), and in vivo markedly inhibits primary tumor growth and blocks metastasis in the MMTV-PyMT model.

The premise is that PIM kinases sit at a node where cell survival, proliferation, and chemo-resistance signals converge in TNBC, and that targeting them either alone or in combination with standard chemotherapy creates a new therapeutic window.