Oxandrolone for the treatment of bone marrow failure in Fanconi anemia

A majority of Fanconi anemia (FA) patients will experience bone marrow failure (BMF) and androgen therapy (most often oxymetholone) may be utilized as a treatment to improve BMF-related cytopenias. However, oxymetholone is associated with toxicities making identification of other agents of interest. In this study we aimed to evaluate the toxicity profile and hematologic response in patients with FA who are treated with low-dose oxandrolone, a synthetic non-fluorinated anabolic steroid, similar to oxymetholone, with known dosing thresholds for virilization.

A single arm, Phase I/II study was designed to treat patients on low-dose oxandrolone. If no toxicity or hematologic response was noted at 16 weeks, a single dose escalation was offered. Subjects were regularly assessed for toxicity, including determinations of virilization, behavioral changes, and liver and kidney function. At 32 weeks, those who demonstrated hematologic response were allowed to continue study treatment, and those without improvement were deemed non-responsive.

Nine subjects completed the study and were followed for a median of 99 weeks (46-136 weeks). Three (33.3%) subjects developed mild sub-clinical virilization and continued treatment with a dose reduction. None (0%) had adverse behavioral changes. Two (22.2%) developed elevated liver function tests at 42 and 105 weeks. Seven (77.8%) subjects had a hematologic response.

Oxandrolone appears to be well-tolerated, has limited toxicities at the administered doses in FA with patients, and may be an alternative androgen for the treatment of BMF in FA.