Kairos Pharma has announced encouraging interim efficacy results from its ongoing phase 2 trial of ENV105 (carotuximab) in patients with metastatic castration-resistant prostate cancer (mCRPC). The trial evaluated ENV105 in combination with apalutamide in patients who had already failed at least one hormone therapy.

The interim analysis of the first ten patients showed a median progression-free survival (PFS) of over 13 months, substantially exceeding the 3.7 months typically observed with second- or third-line hormone therapy alone, as reported by the CARD trial (New Engl J Med 2019; 381:2506). Seven of nine evaluable patients experienced a reduction in prostate-specific antigen (PSA) from baseline. The combination therapy was well tolerated, with no Grade 3 or 4 toxicities observed.

ENV105 is a first-in-class CD105 antagonist designed to address pathways of drug resistance in prostate cancer. Dr John Yu, CEO of Kairos Pharma, said: “While this is only interim data, we are excited to bring together the principal investigators and other industry experts for an important event this afternoon to lay out the primary benefits of our compound, and demonstrate the clinical need filled by ENV105.”

The trial’s design includes enrolling 100 patients across multiple leading US cancer centres, including Cedars-Sinai Medical Center, City of Hope, and Huntsman Cancer Institute. It aims to evaluate safety, tolerability, and early signs of efficacy in men whose disease has progressed despite prior standard hormone therapy. The data from this early cohort provide an initial indication that ENV105 in combination with apalutamide may substantially prolong PFS compared with standard hormonal options.

Notably, standard treatment options for mCRPC beyond first-line hormone therapy remain limited, with many patients turning to chemotherapy, which can provide moderate benefit but carries significant toxicity and longer recovery times. The interim results suggest ENV105 could offer a safer alternative with meaningful efficacy.

Kairos Pharma hosted a virtual key opinion leader (KOL) discussion to provide additional perspective on the interim results. Speakers included trial investigators from Cedars-Sinai, Huntsman Cancer Institute, and Massachusetts General Hospital/Harvard Medical School. The session explored the potential of ENV105 to address drug resistance, improve patient outcomes, and expand therapeutic options in a challenging disease setting.

With prostate cancer affecting over one million men annually in the US and millions worldwide, development of resistance to hormone therapies creates a significant unmet need. ENV105’s interim results indicate that the combination therapy may provide a viable alternative for patients with limited options, potentially shifting the treatment landscape in advanced prostate cancer.