Abaloparatide increases bone mass without affecting growth of bone-disseminated cancer cells.

Breast cancer cells frequently spread to the bone, causing osteoclast-mediated bone destruction and pathological fractures. Bone anabolic agents, such as abaloparatide, are used clinically to increase bone formation in osteoporotic patients, but their effectiveness against tumor-induced bone destruction is poorly understood. In this study, we present the first evaluation of abaloparatide in preclinical models of breast cancer cells disseminated to the bone marrow and demonstrate that intermittent abaloparatide dramatically increases trabecular bone volume in mice inoculated with triple negative breast cancer cells. Abaloparatide also increases BMD in a model of estrogen receptor positive breast cancer, despite elevated baseline bone volume due to estradiol supplementation. Importantly, abaloparatide does not increase tumor burden or incidence in bone or soft tissue sites in either model. These results suggest that abaloparatide may be effectively used to increase bone mass without stimulating growth of cancer cells in the bone marrow and may be beneficial for cancer patients with low bone mass.