The Phase II study is evaluating the combination of an antibody-drug conjugate called Sacituzumab Tirumotecan with an immunotherapy drug, Tagitanlimab, specifically for patients with aggressive variant prostate cancer and neuroendocrine prostate cancer. These rare but devastating subtypes represent a major clinical challenge because they don’t respond to the hormone-blocking treatments that form the backbone of standard prostate cancer care.

Current treatment guidelines for these cancers largely rely on platinum-based chemotherapy regimens borrowed from small cell lung cancer protocols, reflecting the biological similarities between these diseases and the lack of prostate cancer-specific treatments. However, these chemotherapy approaches provide limited benefit and come with significant side effects, leaving patients with few options when cancer progresses.

The experimental combination being tested takes a dual approach to attacking these cancers. Sacituzumab Tirumotecan is an antibody-drug conjugate that targets Trop-2, a protein commonly overexpressed on cancer cells. The drug acts like a guided missile, using the antibody to find cancer cells and then releasing a potent topoisomerase inhibitor that damages DNA and kills the cell. This targeted approach aims to deliver maximum impact to cancer cells while minimizing damage to healthy tissue.

Tagitanlimab works through an entirely different mechanism as a PD-L1 inhibitor, one of a class of drugs known as immune checkpoint inhibitors. These treatments remove the molecular brakes that prevent the immune system from attacking cancer cells, essentially unleashing the body’s natural defenses against the tumor. The drug has shown activity across various cancer types by helping T cells recognize and eliminate malignant cells.

The rationale for combining these two approaches stems from growing evidence that antibody-drug conjugates can make tumors more visible to the immune system.

The single-arm design of the study suggests researchers expect to see meaningful activity from this combination. Rather than comparing the treatment against a control group, investigators will measure response rates, progression-free survival, and overall survival directly, looking for signals that the combination provides clinical benefit to patients who have exhausted other options.

The trial is being conducted in China, where more than 60 percent of newly diagnosed prostate cancer cases are already in advanced stages at the time of detection.

Clinical trial.