Outcomes for Pembrolizumab Stratified by Pemetrexed Maintenance Post Pembrolizumab–Platinum–Pemetrexed Induction in Metastatic Non-Small-Cell Lung Cancer

Aim: We assessed treatment patterns and outcomes in patients with metastatic nonsquamous non-small-cell lung cancer (mNSCLC) who initiated first-line pembrolizumab–platinum–pemetrexed (induction) in US community oncology settings. Methods: Patients initiating induction were retrospectively identified. Patients continuing pembrolizumab afterward underwent chart review. Clinical outcomes were described by maintenance pemetrexed exposure after inverse probability of treatment weighting (IPTW). Results: Median induction pembrolizumab and pemetrexed durations were 5.1 and 4.2 months. Among patients continuing pembrolizumab after induction, 64% received maintenance pemetrexed. Common discontinuation reasons for induction pemetrexed were completion of planned therapy (79%) and partial response (68%) and progressive disease (38%) and toxicity (29%) for maintenance pemetrexed. After IPTW, median overall survival and real-world progression-free survival were longer in patients continuing pembrolizumab with versus without maintenance pemetrexed (20.3 vs 12.0 months and 10.3 vs 5.8 months, respectively). Conclusion: Patient characteristics and planned treatment decisions affect maintenance pemetrexed utilization in the community oncology setting.