Amongst sufferers with high-risk cutaneous squamous cell carcinoma (CSCC), postsurgical therapy with Libtayo (cemiplimab-rwlc) has been discovered to be related to an identical charge of second main tumors (SPTs) in comparison with placebo following postoperative radiotherapy, analysis has proven.
Findings from an evaluation of the section 3 C-POST trial had been introduced on the 2025 ESMO Congress in Berlin.
Throughout the therapy interval, the proportion of sufferers who developed at the least one SPT was 11% within the Libtayo arm (209 sufferers) in contrast with 12% within the placebo arm (206 sufferers); in the course of the research’s follow-up interval, these charges had been 8% and seven%, respectively. Throughout the therapy interval, the cumulative variety of SPTs was 32 with Libtayo versus 82 for placebo, comparable to annualized adjusted annualized SPT charges of 1.23 and a pair of.81, respectively. Within the follow-up interval, 36 complete SPTs occurred within the Libtayo arm versus 41 within the placebo arm, and the annualized SPT charges had been 0.72 and 1.17, respectively.
Throughout the therapy interval, 9% of sufferers within the Libtayo arm had one SPT, 1% had two SPTs, lower than 1% had three SPTs, 0% had 4 SPTs, lower than 1% had 5 SPTs and 0% had six or extra SPTs. Within the placebo arm, these charges had been 8%, 2%, lower than 1%, lower than 1%, 0% and 1%, respectively. Incidence was related in the course of the follow-up interval, with 4% of sufferers in every arm experiencing one SPT and fewer than 1% of sufferers falling into the a number of SPT teams inside every arm.
In a publish hoc evaluation incorporating the primary prevalence of SPTs alongside disease-free survival (DFS) occasions (recurrence or loss of life), efficacy continued to favor Libtayo over placebo. The median DFS on this evaluation was not reached not reached within the Libtayo group versus 21.7 months within the placebo group. At 24 months, DFS charges had been 81.1% with Libtayo versus 59.1% with placebo, and this profit was maintained over time, with charges of 73.4% versus 48.7% at 36 months and 68.4% versus 41.5% at 48 months, respectively.
“The decrease variety of SPTs within the Libtayo arm seemed to be pushed by a small variety of sufferers with a number of SPTs noticed within the placebo arm. The strong [DFS] efficacy sign with Libtayo versus placebo was maintained in a publish hoc evaluation wherein SPTs had been included as [DFS] occasions,” Dr. Danny Rischin, who serves because the director of Medical Oncology on the Peter MacCallum Most cancers Centre in Melbourne, Australia famous within the conclusion of his presentation.
“These potential randomized information recommend that there could also be a subset of sufferers who expertise fewer SPTs with Libtayo, though additional investigation is required.”
What Was Established within the Major Evaluation of the Trial?
With a median follow-up of 24 months, beforehand reported findings from the first evaluation confirmed that sufferers who obtained adjuvant Libtayo after surgical resection and postoperative radiotherapy achieved a median DFS that was not reached in contrast with 49.4 months amongst these handled with placebo (206 sufferers). The estimated 24-month DFS charges had been 87.1% and 64.1%, respectively.
Primarily based on these findings, on Oct. 8, 2025 the U.S. Meals and Drug Administration (FDA) accredited Libtayo for the adjuvant therapy of grownup sufferers with CSCC at excessive threat of recurrence after surgical procedure and radiation.
What Was the Design of the Trial and the Submit Hoc Evaluation?
The section 3 trial is a randomized double-blind placebo-controlled research designed to guage adjuvant Libtayo in sufferers with histologically confirmed CSCC who had undergone full resection with healing intent and accomplished postoperative radiotherapy. Sufferers had been required to have high-risk options, which included nodal extracapsular extension with at the least one lymph node measuring 20 mm or extra, or three or extra concerned lymph nodes; in-transit metastases; perineural invasion; T4 lesions; or recurrent CSCC with a number of further high-risk traits.
Contributors had been randomly assigned to obtain Libtayo or placebo. Partially 1 of the research, sufferers obtained Libtayo at 350 mg intravenously each three weeks for 12 weeks, adopted by Libtayo at 700 mg each six weeks for an extra 36 weeks. These within the management group obtained matched placebo on the identical schedule. Remedy continued till completion of the deliberate length, illness recurrence, or unacceptable unintended effects.
Sufferers who skilled recurrence after finishing placebo therapy or after at the least three months following Libtayo completion had been eligible to enter an optionally available open-label extension section (half 2) to obtain Libtayo at 350 mg each three weeks for as much as 96 weeks.
The median age of sufferers was 71 years within the Libtayo group and 70.5 years within the placebo group. Most sufferers had been 65 years of age or older, representing 73% and 68% of every respective arm. Nearly all of contributors had been male (83% in each arms) and White (90% versus 92%).
Geographically, 43% of sufferers within the Libtayo arm and 44% within the placebo arm had been enrolled from Australia or New Zealand, 18% and 15% had been from North America, and 39% and 41% had been from the remainder of the world.
Most sufferers had resected high-risk tumors situated within the head and neck area (79% within the Libtayo group versus 86% within the placebo group), and 21% and 14% had non–head and neck tumors, respectively. Relating to threat classification, 60% of sufferers within the Libtayo arm and 57% within the placebo arm had been categorized as having nodal high-risk illness; 40% and 43%, respectively, had non-nodal high-risk options.
References
“Evaluation of second main CSCC tumors (SPTs) reported in the course of the C-POST trial, a randomized section 3 research of adjuvant cemiplimab vs placebo for high-risk CSCC” by Dr. Danny Rischin et al., introduced at: 2025 ESMO Congress; October 17-21, 2025; Berlin, Germany. Summary 1603MO.
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