# Efficacy and safety of cosibelimab, an anti-PD-L1 antibody, in metastatic cutaneous squamous cell carcinoma

Source: https://onco.cc/key-papers/paper-ck-301-101-jitc-2023/  
OnCo record `paper-ck-301-101-jitc-2023` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The primary report of the metastatic cohort of CK-301-101: cosibelimab shrank tumours in 37 of 78 patients, most responses were still going at the cut-off, and severe immune side effects were uncommon.

## Summary

Pivotal metastatic cutaneous squamous cell carcinoma cohort of an open-label, multicentre, multiregional, multicohort phase 1 trial of cosibelimab, a PD-L1-blocking IgG1 antibody with a functional Fc domain. Participants received cosibelimab 800 mg intravenously every 2 weeks. The primary endpoint was objective response rate by independent central review using RECIST 1.1; secondary endpoints were duration of response and safety.

Objective response was observed in 37 of 78 participants (47.4 percent, 95% CI 36.0 to 59.1) at a median follow-up of 15.4 months. Median duration of response was not reached (range 1.4+ to 34.1+ months), with response ongoing in 73.0 percent of responders. Immune-related adverse events occurred in 18 participants (23.1 percent), grade 3 in 2 (2.6 percent), with no grade 4 or 5 events and no treatment-related deaths.

## Fields

- Kind: Key paper
- Last checked: 2026-09-24
- Journal: Journal for ImmunoTherapy of Cancer
- Year: 2023
- DOI: 10.1136/jitc-2023-007637
- Authors: Clingan P, Ladwa R, Brungs D, et al.
- Findings: Objective response rate 47.4% (37 of 78; 95% CI 36.0 to 59.1) by independent central review at a median follow-up of 15.4 months.; Median duration of response not reached; 73.0% of responders still responding at data cut-off.; Immune-related adverse events in 23.1%, grade 3 in 2.6%, none grade 4 or 5; no treatment-related deaths.
- What it means: This cohort, with the locally advanced cohort in the label, is the evidence behind cosibelimab's December 2024 US approval. The response rate is of the same order as cemiplimab and pembrolizumab in this cancer, which gives patients a third checkpoint antibody option, though none of the three has been compared head to head.
- Caveats: Single-arm cohort within a phase 1 trial; no comparator.; The 800 mg every 2 weeks dose studied here differs from the 1,200 mg every 3 weeks dose the label recommends; the label says exposure is comparable.; Median duration of response was not yet estimable at the primary report.

## Sources

- Journal for ImmunoTherapy of Cancer 2023: https://doi.org/10.1136/jitc-2023-007637
- PubMed: https://pubmed.ncbi.nlm.nih.gov/37848259/
- ClinicalTrials.gov NCT03212404: https://clinicaltrials.gov/study/NCT03212404

## Connected records

- cancers: [Advanced cutaneous squamous cell carcinoma](https://onco.cc/cancers/advanced-cutaneous-scc/), [Cutaneous squamous cell carcinoma](https://onco.cc/cancers/cutaneous-scc/)
- targets: [PD-L1](https://onco.cc/targets/pdl1/)
- drugs: [Cosibelimab](https://onco.cc/drugs/cosibelimab/)
- companies: [Checkpoint Therapeutics](https://onco.cc/companies/checkpoint-therapeutics/)
- trials: [CK-301-101](https://onco.cc/trials/ck-301-101/)
- journals: [Journal for ImmunoTherapy of Cancer](https://onco.cc/journals/jitc/)

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