Cancer immunotherapies have been life-changing for some people, as these treatments can turn the body’s own immune system against a tumor.
However, these therapies don’t work for everyone and can come with severe side effects, including inflammation. A new experimental therapy, SAR’877, aims to change that by restoring immune cells’ ability to fight cancer.
Scripps Research scientists are testing SAR’877, a bispecific molecule designed to revive exhausted T cells. The results of preclinical work are encouraging, and an ongoing phase 1/2 clinical trial is showing early signs of effectiveness even in those who have stopped responding to other immunotherapies.
According to the report, the drug revives exhausted T cells more precisely than existing approaches without triggering dangerous inflammation. John Teijaro, a professor at Scripps Research and co-senior author of the study, says, “What we showed is that you can deliver the immune-stimulating signal to the cells that need it most.”
Related: Protective Eyewear Essentials: Choosing and Maintaining Safety Glasses for Everyday Risks
The new molecule was designed to fight “T cell exhaustion,” a drop in activity that happens when immune cells face a chronic threat, such as a tumor or long-term infection. As a bispecific molecule, SAR’877 takes a combined approach, using an antibody that targets PD-1 and a weakened version of the cytokine IL-15.
The weakened IL-15 has an effect only on nearby cells and primarily acts on exhausted T cells. This approach allows the drug to selectively activate certain groups of T cells already primed to respond to the virus, rather than broadly stimulating all immune cells.
One of the most unexpected findings from these experiments involved CD4+ “helper” T cells, which support other immune cells rather than directly attacking cancer cells. While cancer immunotherapy has largely focused on revving up CD8+ “killer” T cells, CD4+ cells appeared to play an unanticipated central role in the effectiveness of SAR’877.
The researchers tested the drug’s effect on 12 different mouse tumor models. The drug shrank tumors in all 12 models and completely eliminated tumors in some mice.
Related: Reevaluating Wellness: The Impact of Acupuncture in Comprehensive Health
Teijaro’s lab is now investigating whether combining SAR’877 with anti-inflammatory drugs could further reduce side effects and allow for higher, more effective doses.
The study was published on April 30, 2026, in JCI Insight. They are making progress in cancer immunotherapy.
SAR’877 can revive exhausted T cells without triggering inflammation, which is a significant step forward. Researchers continue to explore the potential of this new therapy, and the treatment options for cancer patients are changing. The focus is on ongoing clinical trials and further research to fully understand the benefits and limitations of SAR’877.
