1αhydroxyvitamin D5 in the Treatment of Metastatic Breast Cancer
Objective: to evaluate the safety and effectiveness of 1α (OH) D5 (Vitamin D5) as a treatment for metastatic breast cancer.
Although a number of patients with localized breast cancer can be adequately treated with surgery and radiation therapy, for the vast majority of patients additional use of conventional chemotherapeutic agents and hormonal therapy is necessary. While initially responsive to various cytotoxic and hormonal modalities, most breast cancers ultimately acquire resistance to current systemic therapies. Thus, the development of effective new therapeutic modalities is critical. Recently, several vitamins and vitamin analogs have been the foci of investigation as therapeutic agents for various malignancies. Amongst various vitamins, vitamin A and vitamin D have shown the most promising results. However, most D vitamins and their derivatives (analogs) cannot be used extensively in humans because they tend to increase calcium levels in blood (called "hypercalcemia") , which results in serious side effects. Many vitamin D analogs have been developed in search of a compound that retains the helpful effects but does not increase calcium in the blood.
We recently synthesized a vitamin D analog called 1αhydroxyvitamin D5 (1α(OH)D5). In all our laboratory studies, 1α(OH)D5 was effective against breast cancer without increasing the blood levels of calcium (i.e., without much toxicity). Thus, we believe that this could be a useful agent in treating advanced breast cancer. However, all previous studies with this drug were in laboratory animals and this is the first study in human subjects. The investigational agent to be used in this study is not approved by the Food and Drug Administration (FDA) for commercial use; however, the FDA is currently reviewing its use in a Phase I/II clinical research study.