How Can Novel Immunotherapies Bolster Radiotherapy in Prostate Cancer?

In a conversation with CancerNetwork^® at the 2026 ASCO Genitourinary Cancers Symposium, Bridget F. Koontz, MD, FASTRO, spoke about novel systemic therapies that may demonstrate the ability to overcome resistance to radiotherapy among aggressive prostate tumors. Although it is currently unclear whether investigational therapies like T-cell engagers can impact radiation sensitivity, she nevertheless noted an “interesting” interplay between prostate cancer and the immune system.

Koontz, medical director of Radiation Oncology Florida Divisions of AdventHealth Cancer Institute, referenced a session at the meeting detailing new treatment options that may show utility in patients with castration-resistant prostate cancer, stating that it shared “great information” about the field’s future. She noted that while modalities like CAR T-cell therapy and T-cell engagers are in their early days across the field, such agents may have an “exciting benefit” on radiosensitization, which may open the door for combination therapies encompassing radiation.

Transcript:

I was very excited [about] a later session here at ASCO GU. There were some nice talks about upcoming systemic therapeutic options. I'm really excited about T-cell engagers. [Regarding] the question about whether it will impact radiation sensitivity, we don't know yet how that works. There's an interesting interplay for prostate cancer and our immune systems. Traditionally, we have felt that a prostate cancer is an immunodepleted cancer. We don't really get a lot of immune response when we treat it, and it seems to be masked from our immune system very well. It's probably why it's such a prevalent cancer.

Radiation works, in part, by stimulating the immune system to attack these cancer cells. As they start to die, [they] perhaps present antigens that the immune system can use to attack. Anything—whether it's CAR-T, T-cell engagers, and where we're headed [with] the other agents—may have an exciting benefit on the radiosensitization. It is still [in the] early days because, right now, they're looking at advanced disease, and it'll be a while, so we're ready to look at combination drugs plus radiation. That's what I'm most excited about, so take a look at that session. It was a great session on advanced disease at ASCO GU prostate day, and there was a lot of great information about what's coming up.

Reference

Rathkopf D. New treatment options for patients with castrate-resistant prostate cancer. Presented at the 2026 ASCO Genitourinary Cancers Symposium; February 26-28, 2026; San Francisco, CA.