Scientists reported several setbacks in the quest for a cure to AIDS on Tuesday, highlighting concerns about inconclusive evidence that links a promising new drug to birth defects.
According to research presented at the 22nd International AIDS Conference in Amsterdam, four cases of “neural tube” defects were recorded among the pregnancies of 426 HIV-positive women in Botswana who took the drug dolutegravir before conception.
Neural tube defects cause severe brain and spinal deformities in the first weeks after conception, and often lead to stillbirth.
The cases amount to a ratio of nearly one defect per 100 pregnancies, compared to the average population rate of about one per 1,000, researcher Rebecca Zash of the Harvard TH Chan School of Public Health explained.
The defects were observed between August 2014 and May this year.
There have been no new reports among the 170 dolutegravir pregnancies monitored since, but “I don’t think we can take much reassurance” from that, Zash said.
Four birth defects in 596 pregnancies was “still seven times higher than other groups, and statistically significant”, she added.
Dolutegravir is a relatively new HIV-suppressor with fewer side-effects and believed to be less likely to spark drug resistance in patients.
Countries targeted by the US PEPFAR AIDS relief fund were on the cusp of rolling it out as the leading antiretroviral therapy (ART), International AIDS Society president Linda-Gail Bekker told AFP.
Botswana was the first country to introduce dolutegravir as a first-line antiretroviral drug for all who need it, including women of child-bearing age.
“This puts a very definite bump in the road,” Bekker said, adding that conference organisers “scurried” to organise last-minute sessions to discuss the consequences of the Botswana results.
Pending clarification, global health agencies have advised that HIV-positive women planning a family should use other antiretrovirals instead.
“I wish so badly that this (data) signal would go away” with further research, Zash told AFP.
In the meantime, “it’s tough but I think we just have to wait” for more information.
On the cure front, there was some bad news too.
A trial to test a new strategy to “kick” the AIDS-causing HIV virus out of its hiding place in human cells, then “kill” it, yielded a disappointing outcome.
Researchers tested the effects of several medicines on top of standard ART in a trial with 60 men recently diagnosed with HIV.
Volunteers received two vaccines meant to coach the body’s immune system to recognise HIV, and another drug to “wake up” the reservoir cells hiding the virus, forcing it to reveal itself and be attacked by the body’s own defences.
But trial participants who received these drugs had no different outcome to those on standard ART, said Sarah Fidler, a professor of HIV medicine at Imperial College London who took part in the research.
“Of course the overall effect wasn’t what we would hope for, but it was definitive,” she told journalists in the Dutch capital.
“All results move the knowledge forward even if they’re somewhat disappointing.”
For scientists, “cure” means weakening HIV to a point where it poses no harm to the infected person and cannot be transmitted to others — allowing people to stop lifelong treatment without any risk.
“A cure remains a top scientific priority,” said researcher Sharon Lewin of the Peter Doherty Institute for Infection and Immunity at the University of Melbourne.
However, “what we’ve learnt, I think over the last decade: this is going to be a very difficult scientific challenge.”
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In another potential setback, a Thai study concluded that a type of “feminising hormone” used by transgender women appears to lower the concentration of a virus-repressing drug, tenofovir, in the blood.
The study was designed to look for possible adverse interactions between hormone therapy and tenofovir used by HIV-negative people to prevent infection from sex.
The outcome does not necessarily mean that hormone therapy renders the virus-repressing drug less effective, said Akarin Hiransuthikul of the Thai Red Cross AIDS Research Centre.
But further research is needed to unlock the potential repercussions.