Effective eradication of leukemic stem cells (LSCs) remains the greatest challenge in treating acute myeloid leukemia (AML). The immune receptor LAIR-1 has been shown to regulate LSC survival; however, the therapeutic potential of this pathway remains unexplored. We developed a therapeutic LAIR-1 agonist antibody, NC525, that induced cell death of LSCs, but not healthy hematopoietic stem cells in vitro, and killed LSCs and AML blasts in both cell- and patient-derived xenograft models. We showed that LAIR-1 agonism drives a unique apoptotic signaling program in leukemic cells that was enhanced in the presence of collagen. NC525 also significantly improved the activity of azacitidine and venetoclax to establish LAIR-1 targeting as a therapeutic strategy for AML that may synergize with standard-of-care therapies.

Initially, patients that respond to cisplatin (DDP) treatment later relapse and develop chemoresistance. Agents that enhance DDP effectiveness will have a significant impact on cancer treatment. We have shown pronounced inhibitory effects of the progesterone-calcitriol combination on endometrial and ovarian cancer cell growth. Here, we examined whether and how progesterone-calcitriol combination potentiates DDP anti-tumor effects in cancer cells. Ovarian and endometrial cancer cells treated with various concentrations of DDP showed a concentration-dependent decrease in cell proliferation. Concurrent treatment of cells with DDP and progesterone-calcitriol ombination potentiated anticancer effects of DDP compared to DDP-calcitriol, or DDP-progesterone treated groups. The anticancer effects were mediated by increased caspase-3, BAX, and decreased BCL2 and PARP-1 expression in DDP and progesterone-calcitriol combination-treated cells. Stimulation of the PI3K/AKT and MAPK/ERK pathways seen in cancer cells was reduced in DDP-progesterone-calcitriol treated cells. Pretreatment of cells with specific inhibitors further diminished AKT and ERK expression. Furthermore, progesterone-calcitriol potentiated the anti-growth effects of DDP on cancer cells by attenuating the expression of SMAD2/3, multidrug resistance protein- 1 (MDR-1), and ABC transporters (ABCG1, and ABCG2), thereby impeding the efflux of chemo drugs from cancer cells. These results suggest a potential clinical benefit of progesterone-calcitriol combination therapy when used in combination with DDP.

The journal retracts the article, “Progesterone-Calcitriol Combination Enhanced Cytotoxicity of Cisplatin in Ovarian and Endometrial Cancer Cells In Vitro”