CheckMate 451: Maintenance immunotherapy fails to improve SCLC survival
medwireNews: Maintenance treatment with nivolumab, either given alone or alongside ipilimumab, does not prolong the overall survival (OS) of patients with extensive-stage small-cell lung cancer (SCLC), the CheckMate 451 investigators have found.
These data were reported at the European Lung Cancer Congress 2019, held in Geneva, Switzerland.
The phase III trial included 834 individuals who had an ongoing complete or partial response or stable disease after four cycles of platinum-based chemotherapy for extensive-stage SCLC. Participants were randomly assigned to receive nivolumab 1 mg/kg plus ipilimumab 3 mg/kg every 3 weeks for four doses followed by a flat dose of nivolumab (240 mg every 2 weeks) or nivolumab alone at the same flat dose or placebo.
The primary endpoint of the study was OS for combination immunotherapy versus placebo, and this did not differ significantly between treatments, at a median of 9.2 and 9.6 months, respectively, and a nonsignificant hazard ratio (HR) of 0.92. The corresponding 1-year survival rates were 41% and 40%.
Therefore, as per the hierarchical statistical plan, the secondary endpoints could not be formally tested for statistical significance and the analyses are descriptive in nature, explained the presenting author Taofeek Owonikoko (Winship Cancer Institute of Emory University, Atlanta, Georgia, USA).
The findings were similar for single-agent nivolumab, at a median OS of 10.4 months compared with 9.6 months for placebo, and respective 1-year OS rates of 44% and 40%.
Maintenance immunotherapy appeared to improve progression-free survival (PFS), doubling the proportion of patients who were progression-free at 6 months, with rates of 20% and 21% for nivolumab with or without ipilimumab, respectively, versus 10% for placebo. The corresponding durations of median PFS were 1.7, 1.9, and 1.4 months, which equated to HRs of 0.72 and 0.67 for the combination and nivolumab alone groups, respectively, relative to placebo.
The clinical benefit rate was also numerically higher with nivolumab plus ipilimumab and single-agent nivolumab than with placebo, at 45% and 47% versus 35%, respectively. The median durations of response were 10, 11, and 8 months respectively.
In light of these results, Owonikoko concluded that although the trial failed to meet its primary endpoint, the PFS and response data point to the “activity of immuno-oncology agents in the maintenance setting.”
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