Today, people living with HIV rely on lifelong antiretroviral therapy (ART), as their immune system alone cannot effectively suppress the virus. Achieving an HIV cure or durable ART-free viral remission, thus, remains an unmet clinical need.

A therapeutic HIV vaccine designed by IrsiCaixa, in collaboration with the Germans Trias i Pujol University Hospital (HUGTiP) and within the framework of the HIVACAT program, is showing encouraging results on its path towards a potential cure.

The vaccine was developed by the former biopharmaceutical company AELIX Therapeutics and expresses the HIVACAT T-cell immunogen (HTI) designed to train the immune system to control HIV replication without daily ART. The preclinical testing in mouse models was conducted at the Comparative Medicine and Bioimage Centre of Catalonia (CMCiB) enabling the safety and toxicology assessment of the vaccine candidate before its application in clinical trials. "The particularly stressful moments came when we had to respond to regulatory requests. We had to be able to provide potency and toxicity data within a short period of time, and in that context, we were always very well supported by the CMCiB", explains Dr Christian Brander, co-founder of AELIX Therapeutics and principal investigator of the T-cell Immunology and Vaccines group at IrsiCaixa.

After promising results in Phase I, the research progressed to Phase II, and recently a Phase IIa clinical trial study conducted across nine Spanish hospitals demonstrated that -along with an immune system-modulating drug- the HTI vaccine is safe and capable of generating an immune response that improves virus control in the absence of ART.  

In late 2024, AELIX Therapeutics announced the acquisition of the HTI vaccine asset by Gilead Sciences, Inc., a leading and pioneering U.S. company in antiviral development, capable of advancing this asset and with a clear commitment to accelerate clinical progression and enhance the global pursuit of an HIV cure. This milestone is further underscored by Gilead's continued success in the field, exemplified by its achievement in August 2025 of receiving EU marketing authorization for a new HIV pre-exposure prophylaxis option.

This success story demonstrates the key role of the CMCiB in enabling translational research. By providing robust preclinical testing capabilities and support during development and validation phases, the centre helps accelerate the journey from innovative concepts to real-world solutions that improve patient health and wellbeing.
 

Bea Mothe, Anuska Llano and Christian Brander. Image credit: IrsiCaixa.