Aviva Bio’s AVA-291 Emerges as Best-in-Class Therapy to Address FDA-Identified Safety Concerns of Testosterone for Women

• At a September 17 historic meeting, FDA details requirements and safety concerns for development of testosterone for women
• AVA-291 (d3-testosterone) has been designed to address the safety concerns highlighted by FDA
• With patent protection through at least 2041, AVA-291 well positioned to support FDA development requirements

CONCORD, Mass.--(BUSINESS WIRE)--Aviva Bio, a biotechnology company developing next-generation hormone therapies, highlighted the importance of advancing testosterone therapies designed for women following the FDA's September 17 public workshop, “Testosterone Use in Menopausal Women.”

The workshop brought together federal health officials, external experts, clinicians, and patient advocates to examine the scientific evidence, regulatory considerations, and critical knowledge gaps surrounding testosterone therapy for women. Discussions emphasized the need for additional long-term safety data, particularly regarding breast cancer and cardiovascular risk, and encouraged pharmaceutical sponsors to advance the development of new treatment options specifically for women.

During the workshop, FDA physician Linda S. Jaffe, MD, identified breast cancer as a significant unresolved safety concern, stating, “Another major potential long-term risk, as we know, is breast cancer.” Dr. Jaffe discussed several possible biological mechanisms through which testosterone could influence breast cancer risk, including its conversion to estrogen through aromatization, both systemically and locally within breast tissue.

“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, PhD, 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.”

A Novel Approach to Testosterone Therapy

Aviva Bio's lead candidate, AVA-291 (d3-testosterone), is a novel, deuterium-substituted form of testosterone designed to retain androgen activity while resisting aromatization.

In a recent presentation at the 2026 American Association for Cancer Research Annual Meeting, AVA-291 demonstrated an approximately 1,000-fold less potential to stimulate breast cancer cell proliferation compared to 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.

Advancing Toward Clinical Development

In a recent Type B meeting, the FDA recommended that Aviva Bio pursue hypoactive sexual desire disorder (HSDD) as AVA-291's initial indication in women.

AVA-291 is supported by a broad and growing intellectual property portfolio, including recently issued U.S. Patent No. 12,090,159, covering treatment of sexual disorders in women using AVA-291. Patent protection is through at least 2041, with likely extension to 2044.

Aviva Bio is preparing for first-in-human studies and actively engaging potential investors and strategic partners to support the program's next phase.

About AVA-291

AVA-291, or d3-testosterone, is an investigational, deuterium-substituted isotopologue of testosterone designed to retain testosterone's androgen activity while resisting aromatization. AVA-291 is being developed for clinical settings in which androgen activity may provide therapeutic benefit but the aromatization of testosterone to estrogen presents safety or tolerability concerns.

About Aviva Bio

Aviva Bio is a biotechnology company unlocking the potential of hormone-based medicine through novel drug design and evidence-based development. Its lead program, AVA-291, is being developed as a next-generation androgen for women and other patient populations with significant unmet medical needs.

For more information, visit http://www.aviva-bio.com/.