PD-1-enhanced HIV DNA vaccine ICVAX shows tolerability, T-cell response in Phase 1
A 45-patient placebo-controlled trial found ICVAX safe in ART-treated HIV-1 patients and more likely than placebo to raise antigen-specific T-cell responses, with viral-reservoir effects left for future study.
Executive Summary
- A placebo-controlled, dose-escalating Phase 1 trial evaluated whether a PD-1-enhanced HIV-1 DNA vaccine could be safely given to people already suppressed on antiretroviral therapy, and whether it could rouse an antigen-specific immune response.
- The vaccine was tolerated across all dose levels tested, and a larger share of vaccinated participants than placebo recipients showed a rise in HIV-specific T-cell activity.
- The trial was not designed to show whether that immune response translates into control of the virus itself, a question the sponsor has flagged for future study.
- The finding adds a dose-ranging safety and immunogenicity data point to a small field of therapeutic HIV vaccine candidates, most of which remain in early testing themselves.
The stake
Antiretroviral therapy (ART) suppresses HIV-1 to undetectable levels but does not eliminate the virus, which persists in a latent reservoir and rebounds if treatment stops. Therapeutic vaccines aim to train the immune system to control that reservoir without continuous drug therapy. ICVAX is a DNA vaccine engineered to co-express a PD-1 immune-checkpoint element intended to strengthen the antigen-specific T-cell response it elicits, tested here in people already on stable ART. SafetySafety and Immunogenicity of a PD-1-Enhanced HIV-1 Therapeutic DNA Vaccine: A Randomized, Double-Blind, Placebo-Controlled, Dose-Escalating Phase I Clinical Trial in People With HIV-1 on Antiretroviral Therapy.Jul 14, 2026
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
How it was done
The trial (NCT06253533) was a randomized, double-blind, placebo-controlled, dose-escalation Phase 1 study conducted at Shenzhen Third People's Hospital in China under an NMPA-approved protocol. Adults with HIV-1, aged 18 to 50 and on ART for at least 12 months with undetectable viral load, were assigned sequentially to 1 mg, 2 mg, or 4 mg dose cohorts of 15 participants each, randomized 12:3 to ICVAX or placebo. Participants received intramuscular injections with electroporation at Weeks 0, 4, 8, 12, and 36, with safety tracked through Week 36 as the primary endpoint and immunogenicity and viral-reservoir measures assessed at Week 60 as secondary endpoints. All 45 enrolled participants completed the trial, with 12 per ICVAX dose cohort and 9 in the pooled placebo group analyzed. NCT06253533+1ICVAX as a HIV Therapeutic DNA VaccineNCT06253533Safety and Immunogenicity of a PD-1-Enhanced HIV-1 Therapeutic DNA Vaccine: A Randomized, Double-Blind, Placebo-Controlled, Dose-Escalating Phase I Clinical Trial in People With HIV-1 on Antiretroviral Therapy.Jul 14, 2026
The result: tolerability and T-cell response
Treatment-related adverse events occurred in 100% of placebo recipients and 83.3% of ICVAX recipients, all described as mild and transient and predominantly local injection-site reactions. On the secondary immunogenicity measure, a doubling or greater rise in peak ELISpot T-cell response over baseline was seen in 75% of the low-dose cohort, 75% of the mid-dose cohort, and 58.3% of the high-dose cohort, compared with 33.3% of placebo recipients. ICVAX recipients also showed low-frequency Gag-specific T cells expressing CD107a and effector cytokines, a marker of functional cytotoxic activity. The trial's registered primary endpoint measured adverse-event incidence for safety and tolerability, not viral control, and the T-cell finding sits within the secondary immunogenicity endpoints rather than the primary outcome. Safety+1Safety and Immunogenicity of a PD-1-Enhanced HIV-1 Therapeutic DNA Vaccine: A Randomized, Double-Blind, Placebo-Controlled, Dose-Escalating Phase I Clinical Trial in People With HIV-1 on Antiretroviral Therapy.Jul 14, 2026ICVAX as a HIV Therapeutic DNA VaccineNCT06253533
What the data don't yet establish
The publication states that ICVAX's efficacy, meaning its effect on the HIV-1 viral reservoir and any capacity to permit reduced or interrupted ART, will be assessed in future studies. The trial's own secondary outcome measuring viral reservoir effect by PCR at Week 60 was registered but is not reported here. The immune response documented is a step toward, not a demonstration of, functional viral control. Safety+1Safety and Immunogenicity of a PD-1-Enhanced HIV-1 Therapeutic DNA Vaccine: A Randomized, Double-Blind, Placebo-Controlled, Dose-Escalating Phase I Clinical Trial in People With HIV-1 on Antiretroviral Therapy.Jul 14, 2026ICVAX as a HIV Therapeutic DNA VaccineNCT06253533
Where this sits in the field
Therapeutic HIV-1 vaccines remain an early-stage approach: five industry and academic trials have tested DNA vaccines in HIV-1 infection to date, with a maximum phase of Phase 2 across five sponsors. The closest comparators by mechanism and indication are BioNTech's RNA-based BNT168 and the University of California, San Francisco's MucoCept-CVN, both also in Phase 1 testing against HIV. Immuno Cure Holding (HK) Limited is separately recruiting a second Phase 1 trial of ICVAX in Hong Kong (NCT07530198), extending the same modality into a new geography.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.