A therapeutic vaccine called VIR201 may help control HIV viral load when antiretroviral treatment is stopped, Australian biotechnology company Virax Holdings Ltd announced this week.
The finding comes from a small extension study conducted by the National Centre in HIV Epidemiology and Clinical Research (NCHECR) in Australia.
In the original phase I/IIa primary infection study, 34 people were randomised to vaccine or placebo in conjunction with combination antiretroviral therapy. Some participants agreed to advance to the extension study which involved interruption of therapy. They received a booster of VIR201 or placebo, and then stopping taking their antiretroviral medication.
“VIR201 performed better than placebo in controlling HIV-infected patients’ viral load,” said Professor David Cooper Director of the NCHECR.
No further details have been announced at this stage but the authors have submitted an abstract for presentation at the Eleventh Conference on Retroviruses and Opportunistic Infections in February.
Earlier this year Virax announced that the phase I/IIa study had failed to find evidence that VIR201 had stimulated HIV-specific immune responses. At the time the researchers did not rule out the possibility that VIR201 might have an impact on markers of HIV disease because the processes which trigger HIV-specific cellular immune responses are still poorly understood.
“This latest data provides a promising preliminary indication which merits further development,” Professor Cooper said.
VIR201 is a genetically modified fowlpox virus which is delivered into human cells using co-expression technology called Co-X-Gene TM. By stimulating cellular production of HIV antigens and cytokines, researchers hope to trigger HIV-specific immune responses and limit viral replication.