Innovations in GU Cancer Treatment at ASCO25

Dr. Neeraj Agarwal and Dr. Jeanny Aragon-Ching discuss important advances in the treatment of prostate, bladder, and kidney cancers that were presented at the 2025 ASCO Annual Meeting. TRANSCRIPT Dr. Neeraj Agarwal: Hello, and welcome to the ASCO Daily News Podcast. I am Dr. Neeraj Agarwal, your guest host of the ASCO Daily News Podcast today. I am the director of the Genitourinary Oncology Program and a professor of medicine at the University of Utah Huntsman Cancer Institute and editor-in-chief of the ASCO Daily News. I am delighted to be joined by Dr. Jeanny Aragon-Ching, a GU medical oncologist and the clinical program director of the GU Center at the Inova Schar Cancer Institute in Virginia. Today, we will be discussing some key abstracts in GU oncology that were presented at the 2025 ASCO Annual Meeting. Our full disclosures are available in the transcript of this episode. Jeanny, it is great to have you on the podcast. Dr. Jeanny Aragon-Ching: Oh, thank you so much, Neeraj. Dr. Neeraj Agarwal: Jeanny, let's begin with some prostate cancer abstracts. Let's begin with Abstract 5017 titled, "Phase 1 study results of JNJ-78278343 (pasritamig) in metastatic castration-resistant prostate cancer." Can you walk us through the design and the key findings of this first-in-human trial? Dr. Jeanny Aragon-Ching: Yeah, absolutely, Neeraj. So this study, presented by Dr. Capucine Baldini, introduces pasritamig, a first-in-class T-cell redirecting bispecific antibody that simultaneously binds KLK2 on prostate cancer cells and CD3 receptor complexes on T cells. KLK2 is also known as human kallikrein 2, which is selectively expressed in prostate tissue. And for reference, KLK3 is what we now know as the PSA, prostate-specific antigen, therefore making it an attractive and specific target for therapeutic engagement. Now, while this was an early, first-in-human, phase 1 study, it enrolled 174 heavily pretreated metastatic CRPC patients. So many were previously treated with ARPIs, taxanes, and radioligand therapy. So given the phase 1 nature of this study, the primary objective was to determine the safety and the RP2D, which is the recommended phase 2 dose. Secondary objectives included preliminary assessment of antitumor activity. So, pasritamig was generally well tolerated. There were no treatment-related deaths. Serious adverse events were rare. And in the RP2D safety cohort, where patients received the step-up dosing up to 300 mg of IV every 6 weeks, the most common treatment-related adverse events were low-grade infusion reactions. There was fatigue and grade 1 cytokine release syndrome, what we call CRS. And no cases of neurotoxicity, or what we call ICANS, the immune effector cell-associated neurotoxicity syndrome, reported. Importantly, the CRS occurred in just about 8.9% of patients. All were grade 1. No patients required tocilizumab or discontinued treatment due to adverse events. So, this suggests a favorable safety profile, allowing hopefully for outpatient administration without hospitalization, which will be very important when we're thinking about bispecifics moving forward. In terms of efficacy, pasritamig showed promising activity. About 42.4% of evaluable patients achieved a PSA50 response. Radiographic PFS was about 6.8 months. And among patients with measurable disease, the objective response rate was about 16.1% in those with lymph node or bone metastases, and about 3.7% in those with visceral disease, with a median duration of response of about 11.3 months. So, altogether, this data suggests that pasritamig may offer a well-tolerated and active new potential option for patients with metastatic CRPC. Again, as a reminder, with the caveat that this is still an early phase 1 study. Dr. Neeraj Agarwal: Thank you, Jeanny. These are promising results for a bispecific T-cell engager, pasritamig, in prostate cancer. I agree, the safety and durability observed here stand out, and this opens the door for further d