ASCO 2026: Key Genitourinary Oncology Trials to Watch For

The 2026 American Society of Clinical Oncology (ASCO) Annual Meeting will feature practice-changing clinical data across multiple oncology subspecialties. For genitourinary (GU) oncology clinicians, the upcoming presentations promise to deliver deep discussions on therapeutic sequencing, patient-reported outcomes, and novel mechanistic strategies.

Saum Ghodoussipour, MD, director of the Bladder and Urothelial Cancer Program at the Rutgers Cancer Institute, and an associate professor of Surgery at Rutgers Robert Wood Johnson Medical School, shared his perspective on the key trials generating the most intrigue in the GU oncology space this year. This preview details some of the major studies poised to redefine clinical workflows and treatment paradigms for bladder and prostate malignancies.

LBA1: Perioperative (neoadjuvant and adjuvant) apalutamide (APA) + androgen deprivation therapy (ADT) vs placebo (PBO) + ADT with radical prostatectomy (RP) in high-risk localized or locally advanced prostate cancer (HR LPC/LAPC): final analysis of the PROTEUS phase 3 study.

Presentation: May 31, 1:05 – 1:17 PM CST by Mary-Ellen Taplin, MD, FASCO

“[E]veryone in the GU space will be watching the phase 3 PROTEUS study [NCT03767244], which randomly [assigned] men with high-risk localized prostate cancer to perioperative apalutamide [Erleada] plus androgen deprivation therapy [ADT] vs placebo plus ADT around radical prostatectomy, with co-primary endpoints of pathologic complete response [pCR] and metastasis-free survival,” Ghodoussipour stated.¹

Specifically, in the study protocol, patients assigned to apalutamide received four 60-mg tablets of apalutamide daily in each 28-day cycle plus ADT. Six cycles of treatment were given neoadjuvantly, followed by radical prostatectomy with pelvic lymph node dissection, followed by 6 adjuvant cycles.² Those enrolled included patients with high-risk disease—defined as grade groups 3 to 5—with an ECOG performance score of 0 to 1.

Neoadjuvant hormonal therapy has been a rapidly expanding area of interest for clinicians treating high-risk prostate populations. As the largest study in this therapeutic space, PROTEUS has garnered significant buzz. Given the clinical demand for structured neoadjuvant approaches to maximize systemic control, PROTEUS is poised to be the definitive "star" of GU oncology.

“There's been substantial interest in neoadjuvant hormonal therapy in this population, including a recently completed trial led by our group, and PROTEUS is by far the largest study in the space, with a design that's going to get a lot of attention,” Ghodoussipour concluded.

4503: Intravesical recombinant BCG combined with chemo-immunotherapy (chemo-IO) as perioperative therapy for patients with muscle-invasive bladder cancer (MIBC): primary analysis of SAKK 06/19.

Presentation: May 29, 3:45 – 3:57 PM CST by Richard Cathomas, MD

“As a urologic oncologist, some [trials] that intrigue me the most include the primary analysis of SAKK 06/19, a phase 2 trial [NCT04630730] testing intravesical recombinant BCG followed by neoadjuvant chemoimmunotherapy [consisting of] cisplatin/gemcitabine plus atezolizumab [Tecentriq] and radical cystectomy in patients with muscle-invasive bladder cancer [MIBC],” Ghodoussipour explained.³

According to data reported in the abstract, the pCR rate per central review was 65% among 40 patients who successfully underwent resection on the trial. A pathologic response was observed in 80% of this group. Grade 3 treatment-related adverse effects (TRAEs) occurred in 9% of patients, and no treatment-related deaths were observed. Moreover, the 1-year event-free survival (EFS) rate was 88% (95% CI, 71%-95%), and the 1-year overall survival (OS) rate was 95% (95% CI, 81%-99%).

Early clinical signals have been highly promising, and the primary analysis of this trial will provide vital data on whether this localized immune priming translates into superior pathological and systemic outcomes.

“The mechanistic premise that intravesical BCG can augment systemic immune activation in the perioperative setting is very interesting, and the early signals have been promising,” Ghodoussipour concluded.

4513: Health-related quality of life (HRQOL) with pembrolizumab or observation for high-risk muscle-invasive urothelial carcinoma after surgery: results from the AMBASSADOR randomized trial (Alliance A031501).

Presentation: May 29, 3:57 – 4:09 PM CST by Ronald C. Chen, MD, MPH, FASCO

The phase 3 AMBASSADOR/Alliance A031501 trial (NCT03244384) previously established a clear disease-free survival [DFS] benefit for adjuvant pembrolizumab (Keytruda) compared with observation in patients with high-risk, muscle-invasive and locally advanced urothelial carcinoma after radical cystectomy.⁴

Specifically, in an interim analysis for DFS and OS at the 2024 ASCO Genitourinary Cancers Symposium, after a median follow-up of 22.3 months, the median DFS was 29.0 months (95% CI, 21.8-not evaluable [NE]) with pembrolizumab vs 14.0 months (95% CI, 9.7-20.2) with observation (HR, 0.69; 95% CI, 0.55-0.87; P = .0013). The difference in OS did not reach significance (HR, 0.98; 95% CI, 0.76-1.26; P = .88).⁵

This highly anticipated subset presentation delves into the trial’s health-related quality-of-life (HRQOL) and patient-reported data.

“The trial showed a [DFS] benefit with pembrolizumab, but we have a limited picture of the patient experience. This presentation digs into patient-reported HRQOL, and we need to be more honest as a field about how we assess the AE burden of treatments that otherwise have clear oncologic benefit,” Ghodoussipour expressed.

Underdogs and Hidden Gems to Watch

Beyond the heavily anticipated phase 2 and phase 3 data readouts, several smaller sessions and translational abstracts could emerge as the real underdogs of ASCO 2026. According to Ghodoussipour, clinicians should monitor the following areas for emerging shifts:

• Liquid biopsy tracking: Compelling new biomarker data in bladder and kidney cancer may soon redefine how early recurrence is caught or how minimal residual disease (MRD) is managed after surgery.
• Next-generation antibody-drug conjugates (ADCs): The continued clinical expansion of novel ADCs is increasing options for advanced genitourinary malignancies.
• Organ-sparing approaches: Rapidly evolving combinations of bladder-directed therapies and systemic agents are aiming to safely challenge traditional radical surgery paradigms, potentially preserving quality of life without compromising survival.

References

1. Taplin M-E, Gleave M, Shore ND, et al. Perioperative (neoadjuvant and adjuvant) apalutamide (APA) + androgen deprivation therapy (ADT) vs placebo (PBO) + ADT with radical prostatectomy (RP) in high-risk localized or locally advanced prostate cancer (HR LPC/LAPC): final analysis of the PROTEUS phase 3 study. J Clin Oncol. 2026;44(suppl 17):LBA1. doi:10.1200/JCO.2026.44.17_suppl.LBA1
2. A study of apalutamide in participants with high-risk, localized or locally advanced prostate cancer who are candidates for radical prostatectomy (PROTEUS). ClinicalTrials.gov. Updated May 8, 2026. Accessed May 29, 2026. https://tinyurl.com/4xc8mxp4
3. Cathomas R, Petrausch U, Hayoz S, et al. Intravesical recombinant BCG combined with chemo-immunotherapy (chemo-IO) as perioperative therapy for patients with muscle-invasive bladder cancer (MIBC): primary analysis of SAKK 06/19. J Clin Oncol. 2026;44(suppl 16):4503. doi:10.1200/JCO.2026.44.16_suppl.4503
4. Chen RC, Dueck AC, Fruth B, et al. Health-related quality of life (HRQOL) with pembrolizumab or observation for high-risk muscle-invasive urothelial carcinoma after surgery: results from the AMBASSADOR randomized trial (Alliance A031501). J Clin Oncol. 2026;44(suppl 16):4513. doi:10.1200/JCO.2026.44.16_suppl.4513
5. Apolo AB, Ballman KV, Sonpavde GP, et al. AMBASSADOR Alliance A031501: phase III randomized adjuvant study of pembrolizumab in muscle-invasive and locally advanced urothelial carcinoma (MIUC) vs observation. J Clin Oncol. 2024;42(suppl 4):LBA531. doi:10.1200/JCO.2024.42.4_suppl.LBA531