Episode 15: Applying ctDNA Practically to Cancer Research and Management

In the latest Oncology Decoded, hosts Manojkumar Bupathi, MD, MS, and Benjamin Garmezy, MD, spoke about circulating tumor DNA (ctDNA) and its utility in the monitoring and management of genitourinary cancers and other disease types. They were joined by their colleague, Arnab Basu, MBBS, MPH, FACP.

The group first provided an overview of ctDNA’s importance in the field, with Basu highlighting his early use of the marker when treating patients with colorectal cancer who were experiencing toxicity in the adjuvant setting. Additionally, Basu characterized tumor-informed vs tumor-uninformed testing, stressing the importance of an approach that monitors for actionable genes, which can then shape targeted decision-making from a therapeutic standpoint. Describing how the chance of a false positive is less than 1%, Basu noted that positive results in the adjuvant setting almost certainly necessitates subsequent therapy for patients.

During the conversation, the experts discussed the applicability of ctDNA based on prior findings from studies like the phase 3 NIAGARA trial (NCT03732677), which showed that higher ctDNA clearance from baseline to the time before radical cystectomy correlated with an enhanced benefit with durvalumab (Imfinzi) plus neoadjuvant chemotherapy. Looking towards the future, the group spoke about the potential use of urine ctDNA testing in bladder cancer, the possibility of investigating the de-escalation of imaging, and the need for further cross-comparison data on different mechanisms of ctDNA testing.

Bupathi is executive cochair of the Genitourinary Cancer Research Executive Committee at Sarah Cannon Research Institute (SCRI) and medical oncologist with Rocky Mountain Cancer Centers specializing in solid tumors and genitourinary cancers. Garmezy is associate director of genitourinary research and executive cochair of the Genitourinary Cancer Research Executive Committee at SCRI and medical oncologist at SCRI Oncology Partners specializing in genitourinary cancers. Basu is the senior associate consultant and a medical oncologist specializing in the care of genitourinary cancers at Mayo Clinic Comprehensive Cance Center.

Reference

Powles T, Van Der Heijden MS, Wang Y, et al. Circulating tumor DNA (ctDNA) in patients with muscle-invasive bladder cancer (MIBC) who received perioperative durvalumab (D) in NIAGARA. J Clin Oncol. 2025;43(suppl 16):4503. doi:10.1200/JCO.2025.43.16_suppl.4503