New Immunotherapy Shows Promise for Early Prostate Cancer

Study finds pairing immunotherapy with hormone therapy may help overcome immune suppression in early-stage prostate cancer.

Published on Feb. 27, 2026

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A multi-institutional study led by Mayo Clinic found that combining a next-generation immunotherapy with standard hormone therapy before surgery may help overcome a long-standing barrier in early-stage prostate cancer treatment. The combination reduced levels of regulatory T cells (Tregs) inside prostate tumors, which normally act as brakes on the immune system and limit the effectiveness of immunotherapy.

Why it matters

Immunotherapy has generally been ineffective for prostate cancer because the tumors are considered "immunologically cold," meaning they do not attract enough immune cells to mount a strong attack. This study provides the first clinical evidence that an engineered anti-CTLA-4 therapy can deplete Tregs within prostate tumors, potentially overcoming this key obstacle and making immunotherapy more effective in early-stage prostate cancer.

The details

In the first-in-human, early-phase randomized trial, researchers tested whether adding a next-generation immunotherapy to hormone therapy before surgery could counteract the immune-suppressing effects of hormone therapy alone. The combination reduced Treg levels inside prostate tumors, and patients whose tumors showed the greatest Treg reductions were more likely to remain cancer-free during follow-up.

  • The study was published in Cell Reports Medicine on February 27, 2026.

The players

Mayo Clinic

A nonprofit organization committed to clinical practice, education and research, providing expert, whole-person care to everyone who needs healing.

Casey Ager, Ph.D.

A cancer immunology researcher at Mayo Clinic and the first author of the study.

Bristol Myers Squibb

A global biopharmaceutical company that develops innovative medicines for patients with serious diseases.

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What they’re saying

“This trial provided a unique opportunity to test a new immunotherapy drug in patients who have localized prostate cancer. They don't have metastatic disease yet, but they are at high risk of reaching that stage. These are patients who possibly can be cured.”

— Casey Ager, Ph.D., Cancer immunology researcher at Mayo Clinic (Mirage News)

“Selective Treg depletion in tumors has been a long-sought goal of the oncology field for some time. We had the opportunity to test a drug that's been engineered to better deplete Tregs than the drugs we previously had. It targets CTLA-4, which is highly expressed on Tregs, particularly within tumors.”

— Casey Ager, Ph.D., Cancer immunology researcher at Mayo Clinic (Mirage News)

What’s next

The researchers plan to further investigate this combination therapy in larger clinical trials to evaluate its potential to prevent progression to metastatic disease in early-stage prostate cancer patients.

The takeaway

This study provides promising evidence that pairing a next-generation immunotherapy with standard hormone therapy may help overcome the immune-suppressing effects that have historically limited the effectiveness of immunotherapy in prostate cancer, potentially offering a new treatment approach for early-stage disease.