Sanofi (NASDAQ:SNY) and Regeneron (NASDAQ:REGN) present positive trial data for the investigational use of PD-1 inhibitor Libtayo (cemiplimab) in first-line locally advanced or metastatic non-small cell lung cancer (NSCLC) at ESMO Virtual Congress 2020. The presentation expands on topline results shared in April.
The Phase 3 trial compared Libtayo monotherapy to platinum-doublet chemotherapy in patients that tested positive for PD-L1 in ≥50% of tumor cells but not ALK, EGFR or ROS1. These results form the basis of regulatory submissions, including in the U.S. and European Union.
In the overall trial population (n=710), the median follow-up was 13 months for both Libtayo and chemotherapy. Among these patients, Libtayo demonstrated the following results compared to chemotherapy:
32% reduced risk of death (hazard ratio [HR]=0.68; 95% confidence interval [CI]: 0.53-0.87; p=0.0022).
22-month median overall survival (OS; 95% CI: 18 months to not yet evaluable) compared to 14 months (95% CI: 12-19 months).
41% reduced risk of disease progression (HR=0.59; 95% CI: 0.49-0.72; p<0.0001). The median progression-free survival (PFS) was 6.2 months (95% CI: 4.5-8.3 months) compared to 5.6 months (95% CI: 4.5-6.1 months).
37% objective response rate (ORR; 95% CI: 32-42%; 3% complete response (CR) and 33% partial response (PR) rate) compared to 21% ORR (95% CI: 17-25%; 1% CR and 20% PR rate).
A prespecified analysis of data whose cancers had confirmed PD-L1 expression ≥50% (n=563) was also conducted. In this group, the median follow-up was 11 months for both Libtayo and chemotherapy, and Libtayo demonstrated the following results compared to chemotherapy:
43% reduced risk of death (HR=0.57; 95% CI: 0.42-0.77; p=0.0002).
Median OS was not yet reached (95% CI: 18 months to not yet evaluable) compared to 14 months (95% CI: 11-18 months).
46% reduced risk of disease progression (HR=0.54; 95% CI: 0.43-0.68; p<0.0001). The median PFS was 8 months (95% CI: 6-9 months) compared to 6 months (95% CI: 5-6 months).
39% ORR (95% CI: 34-45%; 2% CR and 37% PR rate) compared to 20% ORR (95% CI: 16-26%; 1% CR and 19% PR rate).
The trial also found a direct correlation between tumor response and PD-L1 expression level in Libtayo-treated patients. The ORR was highest (46%; range: 36-56%) in tumors with ≥90% PD-L1 expression, with target tumors shrinking by more than 40% after 6 months of treatment on average (per last observation carried forward method). This correlation with PD-L1 expression level was not observed with chemotherapy.
In the overall trial population, the median duration of exposure to Libtayo was 27 weeks and 18 weeks for chemotherapy.
Overall adverse events (AEs) occurred in 88% of Libtayo patients and 94% of chemotherapy patients. Grade 3 or higher AEs occurred in 37% of Libtayo patients and 49% of chemotherapy patients. No new Libtayo safety signals were observed.