A week to the day after a monitoring board told organizers of the clinical vaccine research trial known as HVTN 505 to stop inoculating participants, only a few certainties have surfaced.
One is that the would be vaccine regimen did not prevent HIV infections.
The other is that the search for an effective vaccine will continue.
“The bottom line is that we cannot give up on an HIV vaccine,” Scott Hammer, the trial’s lead researcher said today. “To use the Sisyphus analogy, we’ve got to keep moving the stone up the hill.”
Citing the curse put on the mythological Greek king who was condemned to an eternity of pushing a heavy stone to the top of a hill only to watch it roll back to the bottom and begin again, is about as pessimistic as it gets in the aftermath of disappointing HIV trial results. On the positive side, researchers have eliminated a candidate, and can still glean knowledge from what didn’t happen, and, as Hammer put it, “what was not in this vaccine, that should be.”
Hammer and others involved in the trial reviewed data, discussed preliminary results and answered questions this morning, in an AVAC-sponsored webinar.
Among the good news: data supported the safety of the vaccine. While, as expected, mild adverse reactions comparable to those associated with flu shots were significantly more common among vaccine-receiving participants than placebo-recipients, no seriously “adverse” effects among vaccine recipients were noted. As noted previously, while a slightly higher number of vaccine recipients became infected with HIV in the course of the trial, than placebo recipients, the number was not statistically significant. Of six participants who died of various and unrelated causes in the course of the trial, which began enrolling participants in 2009, all were receiving the placebo.
In addition, researchers emphasized the soundness of the study. Of 2500 men and transgender women enrolled in the trial the dropout rate was just 5.9 percent — about half of what was expected. And during the nearly four years since the trial enrolled its first participant, the world of HIV prevention research yielded other advances, including the effectiveness of pre-exposure antiretroviral treatment (PrEP) and immediate post-exposure treatment to prevent HIV infections, as well as the role treating HIV plays in preventing transmission of the virus. The trial adapted to all of these, including adding the question of whether the vaccine could prevent infection, when the original question of whether it could limit viral load, when the latter question became less relevant in a country where newly diagnosed individuals have the option of immediate treatment. For all of that, Hammer repeatedly praised “the altruism and the heroism,” of participants.
Ahead are possibilities that hundreds of participants in this trial will be eligible for and interested in joining trials in the HIV Prevention Trials Network. More information will be gleaned from the data.
“We got a clear and definitive answer but additional and other questions are raised by this data, as they always are,” Hammer said.
Right now, he said, researchers are still rooted in the present. The trial enrolled its last participants March 27, not even a full month before the findings that ended the trial. Last week, the study was “unblinded,” participants discovering if they had received the placebo or the vaccine, along with discovering the answer they had enlisted to help find remains out of reach.
But whether the stone vaccine researchers are pushing rolled back to the bottom of the hill, or simply remained in place, possibilities continue to evolve, with treatment offering hope that was out of reach when the quest for a vaccine began, and keeping the patience and tenacity the continued quest will consume within reach.