Concord, Mass. — Aviva Bio said its lead candidate, AVA-291, is designed to address safety concerns surrounding testosterone therapy for women that were highlighted during a recent U.S. Food and Drug Administration workshop.
The biotechnology company is developing AVA-291, also known as d3-testosterone, as a deuterium-substituted form of testosterone intended to preserve androgen activity while reducing conversion to estrogen.
The FDA’s Sept. 17 workshop on testosterone use in menopausal women examined scientific evidence, regulatory considerations and gaps in long-term safety data. Discussions included concerns about breast cancer and cardiovascular risk and the need for therapies specifically developed and studied for women.
“Women have been left with an unacceptable choice: go without treatment or rely on products that were not designed, dosed, or comprehensively studied for them,” said Judith A. Boice, Ph.D., Chief Executive Officer of Aviva Bio. “The FDA’s workshop reinforces the importance of developing therapies that address women’s biology, their needs, and the safety questions that have constrained this field for decades.”
Aviva Bio said AVA-291 has been designed to resist aromatization, the process by which testosterone is converted to estrogen.
At the 2026 American Association for Cancer Research Annual Meeting, the company reported that AVA-291 showed about 1,000-fold less potential to stimulate breast cancer cell proliferation than ordinary testosterone in an estrogen receptor-positive breast cancer cell model.
“AVA-291 was designed to address a key safety concern with testosterone use in women, and our findings provide a strong scientific rationale that we have achieved that objective,” said Bradford C. Sippy, Chief Technology Officer of Aviva Bio.
The company said the FDA recently recommended during a Type B meeting that it pursue hypoactive sexual desire disorder as AVA-291’s initial indication in women.
AVA-291 is supported by an intellectual property portfolio that includes U.S. Patent No. 12,090,159, covering treatment of sexual disorders in women using the candidate. Aviva Bio said patent protection extends through at least 2041, with a potential extension to 2044.
The company is preparing for first-in-human studies and is seeking investors and strategic partners to support further development.
AVA-291 remains investigational and is being developed for clinical settings in which androgen activity may provide therapeutic benefit while conversion of testosterone to estrogen may present safety or tolerability concerns.
