S14 Ep48: PSMA Theranostics, ctDNA Testing, and Combination Regimens in GU Oncology Spark Conversation at CFS: With Benjamin P. Levy, MD; Scott T. Tagawa, MD, MS, FACP, FASCO
In today’s episode, filmed live at the 43rd Annual Chemotherapy Foundation Symposium, lung cancer expert Benjamin P. Levy, MD, hosted a cross-specialty discussion with genitourinary (GU) cancer expert Scott T. Tagawa, MD, MS, FACP, FASCO, about the rapidly evolving treatment paradigms for prostate and kidney cancer. Dr Levy is the clinical director of medical oncology at the Johns Hopkins Sidney Kimmel Cancer Center at Sibley Memorial Hospital and an associate professor of oncology at the Johns Hopkins University School of Medicine in Washington, DC. Dr Tagawa is a professor of medicine and urology at Weill Cornell Medicine, as well as an attending physician at NewYork-Presbyterian – Weill Cornell Medical Center in New York, New York.
Their conversation began with a focus on prostate-specific membrane antigen (PSMA)–positive prostate cancer. Dr Tagawa explained that PSMA is a cell surface protein, and that PSMA imaging agents are commonly used to assess biochemical recurrence and perform initial disease staging. He noted that therapy-related adverse effects are often site-specific, including dry mouth/change in taste, and myelosuppression from the radiation payload. For monitoring long-term safety, Dr Tagawa emphasized that renal function must be tracked. Beyond PSMA, other prostate cancer targets include TROP-2, B7-H3, and markers specific to aggressive or neuroendocrine variants, such as DLL3, he reported.
In advanced GU cancers, circulating tumor DNA (ctDNA) testing is increasingly important, Dr Tagawa highlighted. In prostate cancer, ctDNA testing is used to assess homologous recombination deficiency (HRD) status and BRCA expression, he said, explaining that evidence for the use of ctDNA testing in GU cancers stems from findings with this type of assay to evaluate minimal residual disease levels in urothelial cancer. He noted that studies show that if patients with urothelial cancer become ctDNA positive within the first year of receiving neoadjuvant chemotherapy, they benefit from treatment with atezolizumab (Tecentriq). Similarly, he stated that patients with previously untreated HRD-positive metastatic prostate cancer also see a progression-free survival benefit when a PARP inhibitor is added to an androgen deprivation therapy/androgen receptor pathway inhibitor backbone.
Shifting the conversation to the management of frontline advanced clear cell renal cell carcinoma (RCC), the experts reviewed standard approaches, which involve an immune-oncology (IO) agent plus either a CTLA-4 inhibitor or a VEGF TKI. Tagawa noted that IO/VEGF TKI combinations may be preferred for symptomatic patients needing a rapid response, whereas IO/IO combinations may offer greater potential for treatment cessation. He brought up a key distinction in RCC, which is that re-instituting PD-1/PD-L1 inhibition upon progression in the metastatic setting has generally shown no benefit.
Dr Levy brought a broad scope to the GU cancer discussion through his lung cancer expertise, introducing parallels between the treatment paradigms. The interview provided an opportunity to show the importance of creating connections across oncology specialties to bring nuanced perspectives to future advances in clinical research and patient care.
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