Bladder Cancer · Medical · Platinum-Refractory Metastatic · Immunotherapy · 2026-09-18

IMvigor211

In platinum-treated advanced urothelial carcinoma, does atezolizumab improve survival compared with chemotherapy?

Population

931 randomized patients with platinum-treated locally advanced/metastatic urothelial carcinoma.

Intervention

Atezolizumab.

Comparator

Investigator-choice chemotherapy.

Sample size / primary endpoint

931 randomized patients; Overall survival tested hierarchically by PD-L1 expression

Absolute Effect

Primary efficacy result

PD-L1-high population: median OS 11.1 vs 10.6 months; HR 0.87 (95% CI 0.63–1.21; P=.41)

Primary analysis; long-term follow-up subsequently showed durable remissions.

The prespecified primary OS comparison was negative, so formal testing stopped. At 24 months in long-term follow-up, OS was 23% vs 13%.

No statistically valid PFS NNT was established because the hierarchical OS endpoint was not met.

NNT / NNH

NNT: not quantifiable; the primary OS comparison was negative and median survival should not be converted into an NNT.

NNH: 5, based on grade 3–4 treatment-related adverse events (43% vs 20%) in the primary report.

Treatment burden and toxicity

Grade 3–4 treatment-related adverse events were 20% with atezolizumab vs 43% with chemotherapy; discontinuation was 7% vs 18%. Immune-related events were usually low grade.

Quality of life: The toxicity profile favored atezolizumab, particularly regarding severe treatment-related events.

Subgroups / clinically important modifiers

The trial's hierarchical PD-L1 analysis is crucial: the prespecified PD-L1-high population did not meet the OS endpoint.

Limitations and maturity

The primary endpoint was negative. Later durable-response and survival analyses are clinically interesting but do not retroactively convert the primary trial into a positive hierarchical test.

Clinical interpretation

IMvigor211 did not demonstrate the prespecified OS benefit of atezolizumab over chemotherapy, although immunotherapy produced fewer severe treatment-related toxicities and some durable responses.

This negative phase III trial is important evidence against interpreting response durability alone as proof of a population-level survival benefit.

Primary / authoritative sources

IMvigor211 primary phase III report (PubMed)

IMvigor211 long-term update (PubMed)