Dr Bellmunt on Adjuvant Atezolizumab in Patients With MIBC Who Were ctDNA+ After Initial Testing

“There were AEs related to [atezolizumab] but we did not see any unexpected [toxicities].”

Joaquim Bellmunt, MD, PhD, the director of the Bladder Cancer Center and a senior physician at Dana-Farber Cancer Institute, as well as an associate professor of medicine at Harvard Medical School, discussed efficacy data from subgroup analyses, as well as safety results, from the phase 3 IMvigor011 trial (NCT04660344) of circulating tumor DNA (ctDNA)–guided adjuvant atezolizumab (Tecentriq) in patients with muscle-invasive bladder cancer (MIBC).

Beyond the disease-free survival (DFS) and overall survival (OS) benefits reported in patients who were ctDNA positive at their initial test and received adjuvant atezolizumab in IMvigor011, another interesting finding from the study was that a benefit was observed in the investigational arm vs the placebo arm among patients who were positive for ctDNA at a subsequent test, Bellmunt began. Specifically, patients who tested positive for ctDNA at a subsequent test and received atezolizumab (n = 68) achieved a median DFS of 10.5 months (95% CI, 7.1-14.6) compared with 8.3 months (95% CI, 4.2-12.6) in the placebo arm (n = 34; HR, 0.66; 95% CI, 0.40-1.10). The median OS in these subgroups was not estimable (NE; 95% CI, 34.4 months to NE) vs 27.4 months (95% CI, 18.1-NE) in the respective arms (HR, 0.52; 95% CI, 0.24-1.12).

In terms of safety, Bellmunt noted that no unexpected findings were observed with atezolizumab. Patients in the atezolizumab arm who were ctDNA positive (n = 165) experienced any-grade adverse effects (AEs) at a rate of 83.6% compared with 85.5% among patients in the placebo arm (n = 83). Patients in both arms had grade 3 or 4 AEs (28.5% vs 21.7%), any-grade treatment-related AEs (TRAEs; 49.1% vs 50.6%), grade 3 or 4 TRAEs (7.3% vs 3.6%), and any-grade serious AEs (26.7% vs 20.5%).