LIFR inhibition enhances the therapeutic efficacy of HDAC inhibitors in triple negative breast cancer

Li, Viswanadhapalli et al utilized multiple in vitro, ex vivo and in vivo models of TNBC to investigate LIFR inhibition. The authors reported that HDAC inhibition in TNBC cells led to an increase of LIFR expression and over activation of the downstream signaling elements (e.g., STAT3, mTOR, AKT), enhancing the aggressive potential of TNBC cells, and an LIFR inhibitor, EC359, synergistically enhanced the efficacy of HADC inhibitors in suppressing TNBC in vitro and in vivo. Histone deacetylase inhibitors (HDACi) are identified as novel therapeutic agents, however, recent clinical studies suggested that they are marginally effective in treating triple negative breast cancer (TNBC). Here, we show that first-in-class Leukemia Inhibitory Factor Receptor (LIFR alpha) inhibitor EC359 could enhance the therapeutic efficacy of HDACi against TNBC. We observed that both targeted knockdown of LIFR with CRISPR or treatment with EC359 enhanced the potency of four different HDACi in reducing cell viability, cell survival, and enhanced apoptosis compared to monotherapy in TNBC cells. RNA-seq studies demonstrated oncogenic/survival signaling pathways activated by HDACi were attenuated by the EC359 + HDACi therapy. Importantly, combination therapy potently inhibited the growth of TNBC patient derived explants, cell derived xenografts and patient-derived xenografts in vivo. Collectively, our results suggest that targeted inhibition of LIFR can enhance the therapeutic efficacy of HDACi in TNBC.