In Brief

PEPFAR's New Leader Faces Challenges as Program Enters Second Decade

The US President’s Emergency Plan for AIDS Relief (PEPFAR), which has provided life-saving antiretroviral therapy (ART) to more than 6.7 million HIV-infected people in developing countries since its launch in 2003, begins its second decade with a new leader and shifting strategies, and also faces new challenges abroad as countries pass laws criminalizing homosexual behavior that could potentially disrupt HIV/AIDS treatment and prevention efforts on the ground.

In April, the Obama administration appointed Deborah Birx, a US Army colonel and physician with deep roots in the global AIDS fight, as the new Ambassador at Large and US Global AIDS coordinator, placing her in charge of all international HIV/AIDS efforts, including PEPFAR, and making her the program’s fourth leader. Prior to joining PEPFAR, Birx led the US Military HIV Research Program (MHRP) during the launch of the RV144 AIDS vaccine trial in Thailand, which drew intense criticism at the time from several prominent AIDS vaccine researchers, but eventually made history as the first and thus far only vaccine trial to demonstrate efficacy. Birx left MHRP in the midst of the trial to head the US Centers for Disease Control and Prevention’s (CDC) global AIDS program.

Nelson Michael, who worked for Birx during the early days of the RV144 trial and took over the directorship of MHRP when she left, said the US$105 million trial would probably have derailed were it not for her single-minded determination. “It was a rocky time, and there was obviously a lot of discussion in the scientific press,” recalls Michael, referring to a policy forum in Science magazine in which leading scientists raised serious questions about the scientific rationale for the large trial. “But if she thinks something is right, nothing will deter her.”

By the time the surprising results of RV144 were announced in 2009, Birx was already in place at the CDC.  “She didn’t get as much credit as she deserved,” says Michael. “She deserves all the kudos.”

Michael says Birx is politically adept and he was delighted when he first heard she had been nominated to lead the PEPFAR program.

PEPFAR, which was launched in the spring of 2003 by George W. Bush, does much more than provide access to ARVs. In 2013, it also supported HIV testing and counseling for more than 57.7 million people, providing a critical entry point to prevention, treatment, and care services. One challenge facing PEPFAR, and now Birx, is the process of shifting responsibility of PEPFAR-established programs to the host country’s government. PEPFAR, which has already committed more than $52 billion to fight HIV/AIDS, malaria, and tuberculosis, is now trying to strengthen capacity in recipient countries so they can manage their own treatment and prevention programs. Eric Goosby, the previous head of PEPFAR, began the process of shifting responsibility to host countries before leaving PEPFAR late last year to lead a new center at the University of California in San Francisco on implementation sciences that will examine the practicalities of running public health programs and applying business-world efficiencies to improve them.

This process of shifting control over to the recipient countries and getting them to shoulder the costs may be more difficult given the increasing political tension over new anti-homosexuality laws passed in several countries, notably in Uganda, the largest recipient of PEPFAR funding.

The Uganda Legislature also passed a bill on May 13 that includes mandatory HIV testing for pregnant women and their partners, and allows medical providers to disclose a patient’s HIV infection status to others. The bill, which Uganda President Yoweri Museveni is yet to sign into law, also criminalizes HIV transmission, attempted transmission, and behavior that might result in transmission by those who know their HIV status.

Birx responded quickly to the most recent legislation passed in Uganda. “I join with the many health practitioners, HIV/AIDS and human rights activists, multilateral institutions, and individuals everywhere—in Uganda and around the world—in calling for the people and the Government of Uganda to reject this regressive bill,” she noted, in a May 14 release.

Exploring Antibodies to Prevent Mother-to-Child Transmission of HIV

Following the isolation and characterization of dozens of antibodies that can neutralize a broad swathe of HIV isolates, these so-called broadly neutralizing antibodies (bNAbs) are under study in several realms of HIV prevention research, including helping to further reduce rates of mother-to-child transmission (MTCT) of HIV.

Antiretroviral (ARV) prophylaxis during pregnancy, delivery, and breastfeeding is currently the most effective approach to prevent MTCT. But despite widespread efforts to eliminate MTCT, there were 210,000 new pediatric HIV infections in sub-Saharan Africa in 2012, nearly half of which occurred during the breastfeeding period.

The persistence of MTCT of HIV is due to a number of factors. One is identifying HIV-infected pregnant women and prescribing ARV treatment. Another is that ARV prophylaxis requires women to adhere to a once-daily, three-drug suppressive treatment regimen. “The attraction of the antibodies is that they are so long lasting,” said Barney Graham, of the US National Institute of Allergy and Infectious Diseases’ Vaccine Research Center (VRC). “So if you can give it even once a month, it can cover some of the gaps that might occur in daily ARV treatment non-adherence.” ARV prophylaxis during breastfeeding is also not foolproof—breakthrough infections can occur at the rate of 2%-5% by six months.

Studies have shown that some of the recently isolated bNAbs can protect against mucosal challenge in rhesus macaques. In a 2012 study, Brian Moldt of the Scripps Research Institute and colleagues showed that the bNAb known as PGT121 protected three out of five monkeys at the lowest of three antibody doses, and all five monkeys at the two higher doses (PNAS 109, 18921, 2012). And enrollment in a Phase I trial testing the safety and pharmacokinetics of the bNAb VRC01, isolated by researchers at the VRC, is already underway in HIV-infected and uninfected adults. If the results of the Phase I trials are promising, researchers will begin enrollment for a Phase I study in infants born to HIV-infected mothers in the US.

Plans to evaluate the ability of VRC01 to prevent MTCT were outlined as a case study in a recent article, stemming in part from a meeting convened in Uganda in January 2013 by the Global HIV Vaccine Enterprise (PLOS Med.2014, doi:10.1371/journal.pmed.1001616). The focus of the meeting was to develop recommendations on trial designs for evaluating the passive administration of VRC01 in infants, such as sample size and informed consent procedures, as well as to provide broader recommendations on the conduct of clinical trials to prevent HIV infection among breastfed infants in developing countries.

But there are a number of challenges associated with using bNAbs to prevent MTCT, including the high cost of manufacturing these antibodies (see Making it to Manufacturing, this issue) and the logistics of delivering regular injections in the populations where MTCT occurs at the highest rates. In the Phase I trial of VRC01, researchers are evaluating a monthly injection of the antibody in adults by a qualified health professional. But such a regimen may be difficult to implement, said Pontiano Kaleebu of the Uganda Virus Research Institute and a co-author of the PLOS Medicine paper. “In the early stages, when this is being developed, I think that you may find that women are coming [to the clinic], but the question is when you roll out, what will happen?” asked Kaleebu.

Researchers hope that either more potent antibodies or antibodies engineered to have longer half lives will help address these issues. “We hope that we can have antibodies that can be longer lasting so that they don’t have to go to the clinic so many times,” said Kaleebu.

Graham believes that once more potent combinations of antibodies with longer half lives are developed, protection may extend to three months, which could allow mothers to link clinic visits with the World Health Organization’s recommended schedule for childhood vaccinations. Ultimately, he said, it may be possible for the antibodies to last for six months of protection, which would further its practicality.

“They’re at the very initial stages of testing this as a proof-of-concept,” said Yegor Voronin of the Global HIV Vaccine Enterprise and lead author on the PLOS Medicine paper. “Once it works, then you can explore a variety of different ways to improve it.” —Alexandra Morris

Alexandra Morris is a freelance science writer and graduate student at Massachusetts Institute of Technology.