Physicians urge FDA not to approve Truvada as an HIV prevention pill

Last week, a group of 55 U.S. physicians sent a letter to the U.S. Food & Drug Administration (FDA), urging the agency not to approve the use of Gilead's HIV/AIDS treatment drug Truvada for use as an HIV prevention pill - also known as "pre-exposure prophylaxis" (PrEP).

“As medical care providers, we strongly support continued research on the prevention of HIV, but oppose approval of a pre-exposure prophylaxis that runs the risk of contributing to the spread of HIV and drug-resistant viruses. Our first obligation is to do no harm to individuals and to the public health.”

In the letter, spearheaded by AIDS Healthcare Foundation (AHF), the physicians detail a number of concerns raised by first-in humans efficacy data emerging from the iPrEX study of Truvada to prevent HIV transmission. (In the letter, Truvada is referred to by the drug formulation names: tenofovir disoproxil fumarate and emtricitabine or TDF/FTC.) Ultimately, the doctors are concerned that widespread use of PrEP, based on the available data, will unwittingly lead to more risky behavior, and more HIV infections.

The study of 2,499 high-risk men who have sex with men (MSM) found that the once-daily pill could decrease the likelihood of HIV infection by 44%. However, the physicians conclude that this very low result is insufficient to support approval as a prevention tool at this time. The group urges the FDA to not consider approval of the drug as an HIV prevention pill until the final results of all studies are available - still a number of years away.

The letter states: "The first of our numerous concerns is that the iPrEX study results do not pass the threshold for effectiveness. The 44% efficacy that was achieved is well below the threshold generally agreed upon as necessary to be considered effective. The impact of a prophylactic with an efficacy rate of 60% would be considered low. It is unclear why the threshold of acceptability has been lowered so significantly in the case of TDF/FTC."

These concerns come on the heels of an announcement in April of this year by the U.S. Centers for Disease Control and Prevention (CDC) of the abrupt halt of an ongoing study of the use of Truvada as pre-exposure prophylaxis for HIV prevention in women because the, "…trial could not demonstrate efficacy."

The letter continues: "Secondly, the low level of protection achieved in the study was only accomplished as a result of intensive monthly medical visits accompanied by full sexually-transmitted infections (STI) and HIV screening, as well as extensive counseling. This is not equivalent to a real life patient experience. It is logical to anticipate that, in the absence of such support, adherence levels would drop even further."

These concerns appear to be well-founded. An exploratory study, surveying 822 men who have sex with men, was presented last month as part of an HIV PrEP Symposium at UCLA. The online survey, created by AIDS Healthcare Foundation and administered by Research Now, raised questions about the use of Truvada as an HIV prevention pill. The online focus group was designed to determine "real world" reactions from prospective consumers about taking PrEP. The mixed reaction of the survey participants demonstrated the need for further study in the area of patient behavior. To view a summary of the study results, please click here.

Another concern raised by the doctors is "risk compensation" - the concern that people using PrEP may stop using other prevention methods, such as condom use. The physicians state: "Risk compensation is another very serious issue. The iPrEX study results have raised concerns among medical professionals, public health officials and researchers that PrEP may result in increased risky sexual practices if patients believe they are 'biologically protected' while taking TDF/FTC. There may, in fact, be men who are currently using condoms who will stop using them. Sub-optimal adherence could result in a patient becoming infected, developing drug resistance, and then spreading the drug-resistant virus to others. The potential impact of the spread of drug-resistant virus cannot be overstated, as it would be a significant impediment to combating the existing epidemic and a threat to public health."

The letter concludes: "Currently, any physician can prescribe TDF/FTC as PrEP to an HIV negative patient on an off-label basis. An individual medical provider who, in his or her best judgment, believes that a patient will not practice safer sex can prescribe this medication. We support an individual provider's right to do so. However, if the FDA approves a specific indication for the use of TDF/FTC as PrEP, then the drug manufacturers will be free to advertise this use and promote it to providers. We do not believe that this is in the best interest of patients or the public health.

"As medical care providers, we strongly support continued research on the prevention of HIV, but oppose approval of a pre-exposure prophylaxis that runs the risk of contributing to the spread of HIV and drug-resistant viruses. Our first obligation is to do no harm to individuals and to the public health."