Regeneron has fleshed out additional positive data for blockbuster immunotherapy Libtayo (cemiplimab) as an adjuvant therapy in high-risk cutaneous squamous cell carcinoma (CSCC), as rival PD-1 inhibitor Keytruda falters in the same indication.
Regeneron reported that Libtayo, when given after surgery or radiotherapy, achieved a 68% reduction in the risk of disease recurrence or death compared to placebo.
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Results from the Phase III C-POST study (NCT03969004) were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, taking place from 30 May to 3 June in Chicago, Illinois.
Libtayo is already approved in the US and EU for treating patients with advanced CSCC who are not candidates for curative surgery or radiation. CSCC is the second most common type of skin cancer and has a high rate of recurrence.
With a median duration of a two-year follow-up, Libtayo produced a disease-free survival (DFS) of 87%, compared to 64% in the placebo group. Regeneron also touted an 80% reduction in the risk of locoregional recurrence, along with a 65% reduction in the risk of distant recurrence.
No new safety signals were identified in the C-POST trial. Adverse events of any grade occurred in 91% of patients in the Libtayo arm and 89% in the placebo arm.
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By GlobalDataThe results for high-risk CSCC in the adjuvant setting marks a new advancement for immunotherapies, with surgery and radiation being the standard of care.
“There are no additional approved therapies in this setting. Libtayo is the first and only immunotherapy to demonstrate a clinical benefit compared to standard of care surgery and radiation alone. The C-POST data suggest Libtayo could address a critical unmet need for patients and physicians and has the potential to be practice changing,” Regeneron’s clinical development unit head of oncology Israel Lowy told Pharmaceutical Technology.
The results presented at ASCO, which included additional insights for the primary endpoint of DFS and also include results for the secondary endpoints on recurrence measures, follows an interim analysis reported in January this year.
Regeneron stated that the new data, published concurrently in the New England Journal of Medicine (NEJM), has been used to support regulatory applications in the US and EU for approval as a treatment in adjuvant CSCC.
PD-1 rivalry heats up at ASCO
Libtayo is one of Regeneron’s top-selling drugs, generating $1.2bn in sales in 2024. The pharma company secured global rights to Libtayo from co-developer Sanofi for an upfront payment of $900m in 2022. Along with CSCC, it is also approved as a treatment for basal cell carcinoma (BCC), and non-small cell lung cancer (NSCLC).
Analysis by GlobalData’s Pharma Intelligence Centre forecasts sales of $2.6bn by 2031.
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Like Libtayo, MSD’s mega-blockbuster immunotherapy Keytruda (pembrolizumab) – which saw sales of $29.5bn in 2024 – is also approved for advanced CSCC. However, in a rare miss for the PD-1 inhibitor, Keytruda failed to show a significant benefit in the CSCC adjuvant setting, as per data also reported at ASCO.
Lowy is confident in Libtayo’s future growth, with Regeneron eying further indications.
“We believe Libtayo has significant long-term growth potential in CSCC. We estimate that approximately 10,000 CSCC patients face a substantial risk of recurrence in the U.S. and could benefit from adjuvant therapy post-surgery,” Lowy comments.
He adds: “Beyond this setting we are exploring neoadjuvant treatment for resectable CSCC as well as conducting a phase III study of intratumoral injection of Libtayo for patients with earlier stages of CSCC.”
