A Phase II Trial of Pembrolizumab plus Granulocyte-Macrophage Colony-Stimulating Factor in Advanced Biliary Cancer.
Robin Kate Kelley, Paige Bracci, John D Gordan et al.
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In 30 seconds
This single-center phase II trial evaluated pembrolizumab plus GM-CSF in 42 patients with advanced biliary cancers previously treated with chemotherapy and without prior immune checkpoint inhibitor therapy. The confirmed objective response rate was 12% (95% confidence interval, 4-26), including two complete responses; 26% had progression-free survival ongoing at 6 months. The combination was well tolerated, but it did not meet the prespecified response-rate threshold for efficacy. Tumor biopsies showed changes in immune-cell populations and antigen-processing pathways after GM-CSF was added.
Key findings
- The confirmed objective response rate was 12% (95% confidence interval, 4-26), including two complete responses.
- Progression-free survival was ongoing at 6 months in 26% of patients.
- Treatment-related grade 3 to 4 events occurred in 7%, and treatment-related serious adverse events in 10%.
- Tumor PD-L1 expression was present in 46% and associated with a higher rate of 6-month progression-free survival.
Why it matters
The trial provides evidence about a checkpoint-inhibitor combination in previously treated advanced biliary cancer, where checkpoint inhibitor monotherapy has limited activity. Although the response-rate endpoint was not met, some patients had deep responses or prolonged disease control. The observed immune-microenvironment changes offer a rationale for further study, but do not establish clinical benefit from GM-CSF.
What to keep in mind
The study was single-center and phase II, and the combination did not meet its prespecified response-rate threshold for efficacy.