GU Symposium 2016: Updated Results of IMvigor 210 Show Durable Response Rates With Atezolizumab in Advanced Bladder Cancer
In the pivotal phase II IMvigor 210 study, the investigational cancer immunotherapy atezolizumab (MPDL3280A) showed encouraging response rates in patients with locally advanced or metastatic urothelial carcinoma, Roche announced. These data were presented by Hoffman-Censits et al at the 2016 Genitourinary Cancers Symposium (Abstract 355) in San Francisco.
Median overall survival in this heavily pretreated population was 11.4 months (95% confidence interval [CI] = 9.0 to not estimable) in patients with higher levels of programmed cell death ligand 1 (PD-L1) expression, and 7.9 months (95% CI = 6.6–9.3) in the overall study population. The study also showed that 84% (n = 38/45) of people who responded to atezolizumab continued to respond regardless of their PD-L1 status when the results were assessed with longer median follow-up of 11.7 months. Median duration of response has not yet been reached. Atezolizumab was well tolerated, and adverse events were consistent with those observed in previous updates.
“It is encouraging to see that the majority of people with advanced bladder cancer who responded to atezolizumab maintained their response with longer follow-up,” said Sandra Horning, MD, Chief Medical Officer and Head of Global Product Development at Roche..
Study Details
IMvigor 210 is an open-label, multicenter, single-arm phase II study that evaluated the safety and efficacy of atezolizumab in patients with locally advanced or metastatic urothelial carcinoma, regardless of PD-L1 expression. Patients in the study were enrolled into one of two cohorts.
Cohort 1 comprised those who had received no prior therapies for locally advanced or metastatic urothelial carcinoma but who were ineligible for first-line cisplatin-based therapy. The results for this cohort are not yet mature. Cohort 2, for which updated results were announced at the Symposium, included patients whose disease had progressed during or following previous treatment with a platinum-based chemotherapy regimen (heavily pretreated).
Forty-one percent of patients in the study had two or more treatments in the metastatic setting. Patients received a 1,200-mg intravenous dose of atezolizumab on day 1 of 21-day cycles until progressive disease (cohort 1) or loss of clinical benefit (cohort 2).
Coprimary endpoints of the study included confirmed RECIST v1.1 objective response rate per central independent review facility– and investigator-assessed modified RECIST objective response rate. Secondary endpoints included duration of response, overall survival, progression-free survival, and safety. Patients were selected by histology, prior lines of therapy and PD-L1 expression on tumor-infiltrating immune cells, using an investigational immunohistochemistry test currently in development.
In addition to IMvigor 210, Roche has an ongoing randomized phase III study, IMvigor 211, comparing atezolizumab with standard-of-care chemotherapy in patients who have metastatic urothelial carcinoma that worsened after initial treatment.
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