New Guidance Seeks to Inform Development of Anti-HIV Product Class

Posted 26 November 2012 | By Alexander Gaffney, RAC 

A new draft guidance published by the US Food and Drug Administration (FDA) is seeking to assist in the development of a specific class of product-vaginal microbicides-intended to prevent human immunodeficiency virus (HIV) infections.

Vaginal microbicides are chemicals used to treat or prevent infections, and are most commonly physically expressed as topical gels or creams. Researchers have long hoped that vaginal microbicides could be used to prevent the spread of HIV in situations where condoms are unavailable or undesirable.

"Physical barriers such as the condom have been repeatedly demonstrated to have a high efficacy in the prevention of HIV transmission during sexual intercourse, wrote Jonathan Weber et al in a 2005 article published in the Public Library of Science (PLoS).

However, there's a problem: The use of condoms is near impossible without the consent of the male partner in a heterosexual relationship. This can leave females lacking options for preventing HIV infection. "In many settings, women are unable to insist on or negotiate use of condoms or another available prevention method," sometimes because of cultural limitations, observed FDA in its draft guidance.

"A female-controlled method to prevent or reduce HIV risk is highly desirable, especially as this would allow sex education to promote mechanisms for both males and females, with the potential for an additive effect on the reduction of HIV transmission if used with a condom or other barrier methods," explained Weber.

A Sustained Effort

The product class in the last decade has steadily improved, benefiting from a sustained effort on the part of both industry and public health researchers. One of the latter, the Microbicide Trials Network (MTN), is funded by the National Institutes of Health (NIH) and has assisted with dozens of non-clinical and clinical investigations, including several phase II trials.

With the likelihood of therapies advancing into phase III clinical trials and beyond, FDA said in a 23 November 2012 Federal Register posting that it would benefit the industry to have a clear path toward the review and approval of such products.

The draft guidance, Vaginal Microbicides:Development for the Prevention of HIV Infection, "Addresses nonclinical development, early phases of clinical development, phase 3 trial considerations, and safety considerations in vaginal microbicide development, including safety considerations in adolescent and pregnant populations," FDA explained.

In addition, FDA said the guidance provides information on the development of drug-drug or drug-device combinations for microbicide products, and in particular ones meant to treat several indications. FDA also addresses the use of pre-exposure prophylaxis (PrEP) products, which it noted can impact the overall effectiveness of microbicidal products when both products are used concurrently during a clinical trial.

Comments on the guidance are due by 21 February 2012.

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