On September 9, 2025 Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) reported five-year follow-up results on overall survival (OS) from the Phase 3 EMPOWER-Lung 3 trial, which evaluated Libtayo (cemiplimab) plus platinum-based chemotherapy versus chemotherapy alone as a first-line treatment for adults with locally advanced or metastatic non-small cell lung cancer (NSCLC) with no EGFR, ALK or ROS1 aberrations (Press release, Regeneron, SEP 9, 2025, View Source [SID1234655879]). The late-breaking data will be presented in a mini oral session at the IASLC 2025 World Conference on Lung Cancer (WCLC) hosted by the International Association for the Study of Lung Cancer.
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"After more than five years of follow-up, the EMPOWER-Lung 3 trial continues to demonstrate sustained survival – with an impressive overall survival probability of 19.4% at five years – when Libtayo is added to chemotherapy in patients with advanced non-small cell lung cancer," said Ana Baramidze, M.D., Ph.D., Head of Clinical Research Department at Todua Clinic, Tbilisi, Georgia. "Long-term results across tumor histologies were also reported, including a notable 22.3-month median overall survival for squamous NSCLC patients. Collectively, these data underscore Libtayo’s utility across a variety of patient types, both as a single agent and in combination with chemotherapy."
The five-year results for Libtayo plus chemotherapy presented at WCLC add to the breadth of long-term data for Libtayo in advanced NSCLC, including five-year outcomes from the EMPOWER-Lung 1 trial that were presented at WCLC 2024 confirming durable survival benefit as monotherapy.
At this year’s WCLC, five-year efficacy results, with a median follow-up of 60.9 months, found Libtayo plus chemotherapy remained superior to chemotherapy alone:
21.1-month median OS versus 12.9 months, representing a 34% reduction in the risk of death (hazard ratio [HR]: 0.66; 95% confidence interval [CI]: 0.53–0.83). The five-year probability of survival was 19.4% for the Libtayo combination versus 8.8% for chemotherapy.
8.2-month median progression-free survival (PFS) versus 5.5 months, representing a 42% reduction in the risk of disease progression (HR: 0.58; 95% CI: 0.47–0.72).
43.6% objective response rate (ORR) versus 22.1%. The ORR included a complete response rate of 6.4% versus 0%.
16.4-month median duration of response (DoR) versus 7.3 months.
Also presented at WCLC were exploratory subgroup analyses that demonstrated survival benefits for patients treated with Libtayo plus chemotherapy compared to chemotherapy alone regardless of tumor histology or PD-L1 expression level. Specific efficacy results included a:
22.3-month median OS among patients with squamous histology (n=133) versus 13.8 months (n=67), representing a 32% reduction in risk of death (HR: 0.68; 95% CI: 0.49–0.94).
19.4-month median OS among patients with non-squamous histology (n=179) versus 12.4 months (n=87), representing a 38% reduction in risk of death (HR: 0.62, 95% CI: 0.46–0.82).
24.0-month median OS among patients with PD-L1 ≥1% (n=217) versus 12.1 months (n=110), representing a 46% reduction in risk of death (HR: 0.54; 95% CI: 0.41–0.70).
The safety profile at five years remained consistent with previously reported data. The median duration of exposure was 39 weeks to Libtayo plus chemotherapy and 21 weeks to chemotherapy alone. Adverse events (AEs) of any grade occurred in 96.5% of Libtayo plus chemotherapy patients (49% ≥Grade 3) and 95% of chemotherapy patients (33% ≥Grade 3). The most common AEs of any grade occurring in at least 10% of Libtayo plus chemotherapy patients included anemia (46%), alopecia (38%), nausea (25%), increase of alanine aminotransferase (18%), arthralgia (18%), decreased appetite (18%), hyperglycemia (18%), increase of aspartate transaminase (16%), neutropenia (16%), fatigue (15%), constipation (14%), thrombocytopenia (14%), dyspnea (14%), asthenia (13.5%), vomiting (13%), decreased weight (13%), increased blood creatinine (13%), insomnia (12%), hypoalbuminemia (11%), diarrhea (11%). Among Libtayo patients, treatment-related adverse events were ≥Grade 3 in 30% and led to permanent discontinuation in 4.5% and death in 1%, compared to 18%, 1% and 0.7% in the chemotherapy arm, respectively.
About the Phase 3 Trial
The randomized, multicenter Phase 3 trial, called EMPOWER-Lung 3, investigated a first-line combination treatment of Libtayo and platinum-doublet chemotherapy, compared to platinum-doublet chemotherapy alone. The trial enrolled 466 patients with locally advanced or metastatic NSCLC, as well as squamous or non-squamous histologies across all PD-L1 expression levels and with no ALK, EGFR and ROS1 aberrations.
Patients were randomized 2:1 to receive either Libtayo 350 mg (n=312) or placebo (n=154) administered intravenously every 3 weeks for 108 weeks, plus platinum-doublet chemotherapy administered every 3 weeks for 4 cycles. The primary endpoint was OS, and key secondary endpoints were PFS and ORR. The probability of survival and PFS were calculated according to Kaplan-Meier estimates.
Notably, patients in the trial had a variety of baseline characteristics commonly considered difficult-to-treat. Among those enrolled, 43% had tumors with squamous histology, 67% had tumors with <50% PD-L1 expression, 15% had inoperable locally advanced disease not eligible for definitive chemoradiation, and 7% had pretreated and clinically stable brain metastases. Additionally, 84% of patients had an ECOG 1 performance status. ECOG performance status assesses patient ability to conduct daily living activities and prognosis on a scale of increasing severity ranging from 0 (no symptoms) to 5 (death).