amfAR Meeting Calls for Greater Focus on Sex Differences in HIV/AIDS Research and Policy
Nearly two decades after the U.S. government passed legislation to ensure the inclusion of women in research supported by the National Institutes of Health (NIH), many studies still focus only on men. This was one of many topics discussed at amfAR’s cutting-edge consultation meeting “Sex Differences in HIV/AIDS” convened in Bethesda, Maryland, on January 10–11, 2012. Experts in attendance considered how sex differences impact a range of HIV/AIDS-related issues, including the immune system’s role in pathogenesis, methods of prevention, the pharmacokinetics of oral and topical drugs, the impact of hormonal contraceptives on HIV transmission, and the efficacy of ARVs (antiretroviral drugs).
When asked about the impetus for such a meeting, Susan Blumenthal, M.D., amfAR’s senior policy and medical advisor and former U.S. assistant surgeon general, explained, “Recent clinical-trial findings revealing differences in the effectiveness of pre-exposure prophylaxis [PrEP] for men and women underscore the importance of studying sex differences at the molecular, cellular, and organ-system levels and in social and environmental determinants of disease. These factors can have important implications for the treatment and prevention of HIV/AIDS for both sexes now and in the future.”
Ken Mayer, M.D., medical research director at The Fenway Institute, echoed Dr. Blumenthal’s concern regarding recent insights into divergent responses to PrEP among men and women. “These differences may be due to gender variations in mucosal biology, pharmacology, and/or adherence practices, and improved understanding will be vital in order to develop successful strategies to end the epidemic,” he said.
Beyond PrEP, experts at the meeting discussed the role sex differences may play in the efficacy of treatment regimens. Judith Currier, M.D., professor of medicine in the Division of Infectious Diseases at the David Geffen School of Medicine at the University of California, Los Angeles, noted, “A key concern surrounding sex differences in existing antiretroviral therapies is the need to more closely examine reasons for discontinuation of ART in women and to determine whether low-level toxicities preclude women from tolerating and staying on treatment.”
Discussing topical antiretroviral microbicides, Sharon Hillier, Ph.D., professor in the Department of Obstetrics, Gynecology and Reproductive Sciences at the University of Pittsburgh School of Medicine, pointed out that existing data related to sex differences are not sufficient to answer many fundamental questions, including how much drug is needed for how long in which cells to block HIV infection.
Carl Dieffenbach, Ph.D., director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases (NIAID), emphasized in the discussion that while research is needed to illuminate sex-based differences in HIV/AIDS at the biological level, social and behavioral factors make up a significant portion of the equation.
Given these gaps in knowledge, participants at the meeting generated recommendations for future research. Ward Cates, M.D., MPH, distinguished scientist and president emeritus of research at FHI 360, explained, “Three important research areas emerged from the amfAR consultation: 1)understanding the molecular complexity of the hormonal-immunologic interface; targeting preventive ARVs to those most likely to transmit or acquire the virus; and evaluating how best to address behavioral, social, and structural barriers that may contribute to gender inequities in access to treatment, preventive services, and care.”
As next steps, amfAR will convene a Capitol Hill briefing on sex differences in HIV/AIDS and release an issue brief that summarizes scientific knowledge in this field, providing a roadmap for future research and policy actions.