medwireNews: Safety issues have been raised regarding the use of pembrolizumab in patients with multiple myeloma following the halting of two clinical trials testing the programmed cell death 1 (PD-1) inhibitor in combination with one of two immunomodulatory agents.
However, the US FDA emphasizes that the statement’s caution does not apply to the use of pembrolizumab for approved indications, such as melanoma, lung cancer, and urothelial carcinoma.
The KEYNOTE-183 study of 249 patients with relapsed or refractory multiple myeloma was suspended following interim results indicating a trend towards poorer overall survival (OS) with pomalidomide plus dexamethasone and pembrolizumab than the immunomodulatory agent regimen alone.
At data cutoff, after a median follow-up of 8.1 months, the hazard ratio (HR) for death was 1.61 with pembrolizumab and the objective response rate was also lower than that with the immunomodulatory regimen alone (34 vs 40%). Exploratory time-to-progression analysis gave a nonsignificant HR of 1.14.
And patients given pembrolizumab were also more likely than controls to experience grade 3–5 side effects (83 vs 65%) and serious adverse events (63 vs 46%).
Similarly, interim findings led to the discontinuation of the KEYNOTE-185 study of lenalidomide plus low-dose dexamethasone with or without pembrolizumab in 301 newly diagnosed multiple myeloma patients ineligible for autologous stem cell transplantation.
At a median of 6.6 months, the hazard ratio for OS was a nonsignificant 2.06 with the use of pembrolizumab, and the exploratory time-to-progression HR was 0.55. This was also accompanied by a 22 percentage point increase in the rate of grade 3–5 side effects (72 vs 50%) and an increased risk for severe adverse events (54 vs 39%).
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