# C-POST: adjuvant cemiplimab versus placebo in high-risk cutaneous squamous cell carcinoma

Source: https://onco.cc/key-papers/paper-c-post-adjuvant-cemiplimab-nejm-2025/  
OnCo record `paper-c-post-adjuvant-cemiplimab-nejm-2025` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A year of cemiplimab after surgery and radiotherapy for high-risk cutaneous squamous cell carcinoma cut the risk of recurrence or death by more than two thirds, the first adjuvant therapy to work in this skin cancer.

## Summary

Phase 3 placebo-controlled trial of 415 patients with cutaneous squamous cell carcinoma at high risk of recurrence after surgery and postoperative radiotherapy (nodal disease with extracapsular extension, in-transit metastases, perineural invasion or recurrent tumours) randomised to cemiplimab or placebo for up to 48 weeks.

Disease-free survival at 24 months was 87.1 versus 64.1 percent (hazard ratio 0.32), with reductions in both locoregional and distant recurrence; grade 3 or higher adverse events were 23.9 versus 14.2 percent.

## Fields

- Kind: Key paper
- Last checked: 2026-09-17
- Journal: New England Journal of Medicine
- Year: 2025
- DOI: 10.1056/NEJMoa2502449
- Authors: Rischin D, Porceddu S, Day F, et al.
- Findings: 24-month disease-free survival 87.1 percent vs 64.1 percent; hazard ratio 0.32.; Freedom from locoregional recurrence hazard ratio 0.20; from distant recurrence 0.35.
- What it means: Adjuvant cemiplimab is a new standard for high-risk cutaneous squamous cell carcinoma after surgery and radiotherapy, particularly in patients with extracapsular nodal extension.
- Caveats: Overall survival data immature.; Immunosuppressed and transplant patients, who bear much of the disease burden, were excluded.

## Sources

- N Engl J Med 2025: https://doi.org/10.1056/NEJMoa2502449
- PubMed: https://pubmed.ncbi.nlm.nih.gov/40454639/

## Connected records

- cancers: [Advanced cutaneous squamous cell carcinoma](https://onco.cc/cancers/advanced-cutaneous-scc/)
- drugs: [Cemiplimab](https://onco.cc/drugs/cemiplimab/)
- journals: [New England Journal of Medicine](https://onco.cc/journals/nejm/)

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