Longer-Term Analysis Finds Survival Benefit of Atezolizumab in Metastatic Bladder Cancer

By Reuters Staff

May 25, 2021

NEW YORK (Reuters Health) - A long-term analysis of the IMvigor211 clinical trial shows that patients with metastatic bladder cancer who received atezolizumab lived longer and had more manageable side effects compared with those who received chemotherapy.

Atezolizumab is an anti-PD-L1 immune-checkpoint inhibitor used in the treatment of locally advanced or metastatic urothelial carcinoma (mUC) after prior platinum-containing chemotherapy, regardless of PD-L1 status.

In the IMvigor211 trial, patients with mUC and disease progression during or after platinum-based chemotherapy were randomly allocated to atezolizumab 1,200 mg or chemotherapy (vinflunine 320 mg/m2, paclitaxel 175 mg/m2, or docetaxel 75 mg/m2 according to investigator choice) every three weeks.

In the primary analysis (https://bit.ly/3eUVob4), atezolizumab was not statistically significantly better than chemotherapy in terms of overall survival in the prespecified population of patients with PD-L1 ≥ 5% (median OS, 11.1 vs. 10.6 months; stratified hazard ratio, 0.87; 95% confidence interval, 0.63 to 1.21) at median follow-up of 17.8 months.

However, an exploratory analysis of the intent-to-treat (ITT) population showed numerically better OS (median 8.6 vs. 8.0 months; stratified HR, 0.85; 95% CI, 0.73 to 0.99) and 12-month OS rates (39% vs. 32%) among patients receiving atezolizumab versus chemotherapy.

The study team now reports a long-term overall survival and safety update in the ITT population, with patients followed for an additional 16.5 months since the primary analysis.

There ITT population comprised 467 patients in the atezolizumab group and 464 in the chemotherapy group.

"The OS rates were higher among ITT patients receiving atezolizumab at 24 mo (23% vs 13%) and 30 mo (18% vs 10%), and across PD-L1 subgroups, than among those who received chemotherapy," report Dr. Michiel van der Heijden, with Netherlands Cancer Institute, Amsterdam and colleagues report in European Urology.

"Although the primary analysis did not demonstrate statistically significant longer OS for patients receiving atezolizumab versus chemotherapy, updated OS showed long-term durable remission," they note.

Long-term safety and tolerability findings are consistent with the primary analysis, "with no new signals detected."

Patients treated with chemotherapy experienced more grade-3 to -4 treatment-related adverse events (43% vs. 22%) and more AEs leading to treatment discontinuation (18% vs. 9%). Immune-related rash was the most common AE of special interest (21% with atezolizumab and 12% with chemotherapy).

"The benefit-risk profile of atezolizumab remained consistent with that from the primary analysis and the known safety profile of atezolizumab in patients with mUC. Our findings suggest the potential for long-term survival in this setting and support the recommended use of atezolizumab in prior platinum-treated patients with mUC regardless of PD-L1 status," the authors conclude.

The study was sponsored by F. Hoffmann-La Roche Ltd. and Genentech, Inc., a member of the Roche Group, which sells atezolizumab under the brand name Tecentriq. Several authors have disclosed financial relationships with the company.

SOURCE: https://bit.ly/2Rqt0FA European Urology, online April 23, 2021.

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