# Cosibelimab

Source: https://onco.cc/drugs/cosibelimab/  
OnCo record `cosibelimab` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Cosibelimab is a PD-L1 antibody approved in December 2024 for advanced cutaneous squamous cell carcinoma, offering a third immunotherapy choice.

## Summary

Cosibelimab is an IgG1 monoclonal antibody against PD-L1 that keeps a functional Fc region, so in addition to blocking the PD-1/PD-L1 checkpoint it can trigger antibody-dependent cellular cytotoxicity against PD-L1-expressing cells. It is used for metastatic or locally advanced cutaneous squamous cell carcinoma that cannot be cured by surgery or radiation. In the pivotal phase 1 expansion cohorts the response rate was 47% in metastatic disease and 48% in locally advanced disease, with durable responses. A December 2023 complete response letter citing third-party manufacturing inspection findings delayed approval, and the FDA approved it in December 2024 as a third immunotherapy option after cemiplimab and pembrolizumab. Sun Pharma acquired Checkpoint Therapeutics in 2025. Whether the ADCC-competent Fc adds clinical benefit over standard PD-1 antibodies has not been tested head to head.

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-24
- Tags: gap-fill
- Brand: Unloxcyt
- Modality: Anti-PD-L1 monoclonal antibody (IgG1, ADCC-competent)
- Mechanism: Blocks PD-L1 while retaining an active Fc for antibody-dependent cellular cytotoxicity against PD-L1-expressing cells.
- Approvals: US 2024: Metastatic or locally advanced cutaneous SCC not curable by surgery or radiation

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Cosibelimab
- CK-301-101 metastatic cohort (JITC 2023): https://doi.org/10.1136/jitc-2023-007637
- Unloxcyt label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=06bdadd5-d2db-406f-a3f8-de47f48a52e3

## 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/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- targets: [PD-L1](https://onco.cc/targets/pdl1/)
- companies: [Checkpoint Therapeutics](https://onco.cc/companies/checkpoint-therapeutics/), [Sun Pharmaceutical Industries](https://onco.cc/companies/sun-pharma/)
- pathways: [PD-1 / PD-L1 immune checkpoint & T-cell activation](https://onco.cc/pathways/pd1-checkpoint/)
- trials: [CK-301-101](https://onco.cc/trials/ck-301-101/), [Study of Pemetrexed+Platinum Chemotherapy With or Without Cosibelimab in First Line Metastatic Non-squamous NSCLC](https://onco.cc/trials/nct04786964/)
- key papers: [Efficacy and safety of cosibelimab, an anti-PD-L1 antibody, in metastatic cutaneous squamous cell carcinoma](https://onco.cc/key-papers/paper-ck-301-101-jitc-2023/)

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