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Bladder Cancer · Medical Oncology · Evidence review 2026-10-14

KEYNOTE-361

In untreated advanced urothelial carcinoma, did adding pembrolizumab to platinum-based chemotherapy improve PFS or OS versus chemotherapy alone?

Population
1,010 patients with untreated locally advanced unresectable or metastatic urothelial carcinoma randomized among pembrolizumab plus chemotherapy, pembrolizumab alone and chemotherapy alone.
Experimental treatment
Pembrolizumab 200 mg every 3 weeks plus gemcitabine and cisplatin or carboplatin for up to six chemotherapy cycles; a separate pembrolizumab monotherapy arm was also studied.
Comparator
Gemcitabine plus cisplatin or carboplatin for up to six cycles.
Study design
Phase III randomized trial

Key reported outcomes

Values are reproduced from the linked sources. Bars are a visual aid and are scaled within each outcome row; do not compare bar lengths across different endpoints.

Median progression-free survival
Treatment
8.3 months
Comparator
7.1 months
Median overall survival
Treatment
17.0 months
Comparator
14.3 months
OS hazard ratio
Treatment
0.86
Comparator
1.00

For pembrolizumab plus chemotherapy versus chemotherapy, median PFS was 8.3 versus 7.1 months (HR 0.78; nominal P=0.0033) and median OS 17.0 versus 14.3 months (HR 0.86; nominal P=0.0407). The prespecified statistical boundary for OS was not crossed, so formal superiority was not established.

Critical appraisal

The trial's hierarchical testing plan matters: nominal P values cannot be interpreted as a positive confirmatory primary result after the required boundary was missed. Avoid describing the combination as practice-changing based on this study.

Absolute-effect discipline: NNT/NNH is not calculated unless a defensible absolute difference and a common time horizon are available. Median survival differences and hazard ratios alone are not converted into NNT.

Current-practice context

Reviewed 2026-10-14; this is a dated evidence-context note, not a substitute for local guidelines or individual clinical judgement.

Historical negative/unsuccessful confirmatory phase III trial for pembrolizumab plus chemotherapy. Contemporary first-line options have changed, including EV–pembrolizumab and nivolumab plus gemcitabine–cisplatin for selected cisplatin-eligible patients; use current local guidelines.

Freshness status: this page has a dated context and source links, but is not a claim that every relevant guideline or subsequent publication has been exhaustively reviewed.

Sources