Cemiplimab Monotherapy in Metastatic NSCLC: Insights from the CEMI-SPA National Spanish Cohort

In 150 patients with metastatic NSCLC and PD‑L1 ≥50%, the CEMI‑SPA national Spanish cohort clarifies real‑world effectiveness and safety of first‑line cemiplimab monotherapy.

These cohort-level data indicate cemiplimab remains a practical first‑line monotherapy option for high–PD‑L1 patients treated outside clinical trials.

This retrospective, multicenter national cohort enrolled patients across 21 Spanish centers and included 150 treatment‑naïve metastatic NSCLC patients who received first‑line cemiplimab monotherapy with PD‑L1 TPS ≥50%. Effectiveness outcomes showed a 56.9% objective response rate (ORR) and a median PFS and OS of 8.1 and 12.6 months, respectively—real‑world survival metrics are broadly consistent with randomized trials of single‑agent PD‑1 therapy and supportive of comparable effectiveness in routine practice.

When it comes to safety, immune‑related adverse events (irAEs) occurred in 28.7% of patients, with treatment discontinuation for toxicity in 13.3%. The most common irAEs were hepatitis and pneumonitis (each ~6%); grade ≥3 irAEs were seen in ~12% and one treatment‑related death was reported. Routine‑practice ascertainment likely undercounts lower‑grade events because of variable documentation and less frequent monitoring in retrospective cohorts. Emphasis on baseline hepatic and pulmonary screening, early recognition of toxicity, and ready access to immunosuppression protocols is prudent; overall tolerability in routine practice aligns with expectations from pivotal studies.

Performance status was the strongest prognostic factor. ECOG ≥2 independently predicted shorter PFS (multivariate HR 1.78, 95% CI 1.01–3.09) and worse OS (HR 2.6, 95% CI 1.50–4.56). Median PFS was 8.2 months for ECOG 0–1 versus 1.6 months for ECOG ≥2; median OS was 13.8 months versus 1.7 months, respectively. This effect persisted after multivariable adjustment, underscoring that baseline functional status strongly associates with survival on single‑agent PD‑1 therapy in observational data (association, not causation). In practice, these results help identify patients most likely to derive durable benefit from cemiplimab monotherapy and frame realistic expectations for those with ECOG ≥2.