medwireNews: Adding pembrolizumab to etoposide plus platinum (EP) continues to improve the outcomes of treatment-naïve people with extensive-stage small-cell lung cancer (SCLC) in the long term, suggest follow-up data from KEYNOTE-604.
Reporting the findings at the IASLC World Conference on Lung Cancer 2022 in Vienna, Austria, investigator Charles Rudin (Memorial Sloan Kettering Cancer Center, New York, USA) said that the pembrolizumab combination was associated with “clinically meaningful” improvements in overall survival (OS) and progression-free survival (PFS) versus EP after approximately 3.5 years of follow-up.
The OS rate at the 3-year timepoint was nearly tripled with the addition of pembrolizumab to EP, while the PFS rate was around 14 times higher, he highlighted.
Session discussant Virginie Westeel, from Hospital Jean Minjoz in Besançon, France, said that “these results confirm the current standard treatment with platinum-based chemotherapy and immune checkpoint inhibitor.”
Previously the phase 3 trial showed significantly better PFS among the 228 participants who were randomly assigned to receive pembrolizumab 200 mg every 3 weeks alongside four cycles of EP followed by up to 31 cycles of maintenance pembrolizumab than among the 225 given placebo plus EP followed by maintenance placebo.
The hazard ratio (HR) for OS also favored the addition of pembrolizumab in this analysis, but “the prespecified significance threshold was not met,” said Rudin.
He presented data from the latest analysis – conducted at a median of 43.3 months – in which once again OS was better with pembrolizumab plus EP than with placebo plus EP, at an HR for death of 0.76, and respective median durations of 10.8 and 9.7 months.
Of note, the 3-year OS rate was 15.5% in the pembrolizumab group compared with 5.9% in the placebo group, reported Rudin, adding that the benefit associated with the use of pembrolizumab is similar to that seen with other immune checkpoint inhibitors in this disease.
The presenter commented that the PFS results were “even more impressive,” as pembrolizumab continued to be associated with a benefit at the 3-year mark, despite the fact that the treatment duration was no longer than 2 years.
The PFS rate at 3 years was 6.9% for participants who received pembrolizumab plus EP and 0.5% for those given placebo plus EP, and the HR for progression or death was 0.70.
With regard to response, there was “very little durability” in the control arm, said Rudin. Specifically, the proportion of patients with a response duration of at least 36 months and of at least 42 months was 11.5% and 10.1%, respectively, in the pembrolizumab arm, compared with 0.8% for both in the placebo arm.
Rudin concluded that “these results support continued exploration of pembrolizumab-based combinations for the treatment of small-cell lung cancer, and I think more broadly building on the benefit that we’ve seen with immunotherapy.”
And he added that there are a number of ongoing trials within this space.
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IASLC World Conference on Lung Cancer 2022; Vienna, Austria: 6–9 August