Cosibelimab Achieves Promising Responses in Metastatic Cutaneous Squamous Cell Carcinoma


Patients with metastatic cutaneous squamous cell carcinoma who were treated with cosibelimab experienced a positive objective response rate.

Cosibelimab (CK-301) met the primary end point of objective response rate (ORR) in patients with metastatic cutaneous squamous cell carcinoma (CSCC) as part of a registration-enabling phase 1 clinical trial (NCT03212404), according to a press release by the drugs’ developer, Checkpoint Therapeutics.1

Based on independent central review, the ORR was 47.4% (95% CI, 36.0%-59.1%) among those treated with cosibelimab. Moreover, the safety profile appeared consistent with prior findings. Additional information will be shared at an upcoming medical meeting, with plans to submit a biologics license application later in the year, as well as a marketing authorization application in Europe.

“These impressive results demonstrate that cosibelimab, a novel PD-L1 antibody with a unique two-fold mechanism of action, has the potential to offer physicians a new treatment option that provides compelling efficacy, complemented by a favorable tolerability profile, for patients living with this devastating disease,” co-principal investigator Philip Clingan, MD, a medical oncologist and a professor at Southern Medical Day Care Centre in Australia, said in the press release.

A total of 78 patients with metastatic CSCC were enrolled into the cohort with the use of RECIST 1.1 criteria. Patients were received cosibelimab at a fixed dose of 800 mg every 2 weeks. At the time of data cutoff, the median duration of response had not been reached, and 76% of patients had ongoing responses.

Aside from the CSCC cohort, a total 201 patients enrolled across all cohorts with advanced disease, including lung, head and neck, and endometrial cancer. The majority of treatment-emergent adverse effects (TEAEs) were grade 1 or 2.

Preliminary safety and efficacy findings from the multicohort study indicated that at the data cutoff point of August 2020, 114 patients were enrolled with multiple tumor types and treated with cosibelimab. In this population, 103 patients had 1 or more TEAEs, 42 had grade 3 or higher adverse effects (AEs), and 6 had grade 3 or higher AEs related to treatment.2 Frequent AEs included fatigue (25%), anemia (21%), rash (18%), and nausea (16%). The most common drug-related AEs were fatigue (15%) and rash (14%).

A total of 42 patients with cSCC had evaluable responses, with the group experiencing an ORR of 55% (95% CI, 39%-70%). Additionally, 5 patients achieved complete responses, 20 had ongoing responses, and 10 responses were observed in 6 months or less by data cutoff. Twenty-five patients with NSCLC had an ORR of 44% (95% CI, 24%-65%), 5 patients with ongoing responses, and 10 with responses lasting 6 months or longer.

If cosibelimab is approved, Checkpoint Therapeutics hopes to the agent at a lower price point than other currently available PD-L1 therapies. Moreover, the makeup of the treatment could make it desirable as part of a combination regimen.

Moving forward, Checkpoint Therapeutics will continue to enroll patients with cSCC into the registration-enabling cohort. They are also continuing the phase 3 CONTERNO trial (NCT04786964) with cosibelimab plus pemetrexed and platinum chemotherapy for first-line treatment of non-squamous non–small cell lung cancer.

“We are thrilled to report these topline results from our pivotal trial of cosibelimab in metastatic cutaneous squamous cell carcinoma. We believe the strong ORR result is attributable to cosibelimab’s differentiated, two-fold mechanism of action of engaging both T-cells and natural killer cells, while also demonstrating a potential favorable safety profile through its binding to PD-L1, reported in literature as associated with lower rates of severe or worse adverse events as compared to PD-1 therapy,” James F. Oliviero, president and chief executive officer at Checkpoint concluded.


1. Checkpoint Therapeutics announces positive topline results from the registration-enabling trial of cosibelimab in metastatic cutaneous squamous cell carcinoma. News Release. Checkpoint Therapeutics. January 25, 2022. Accessed January 31, 2022.

2. Harris D, Brungs D, Ladwah R, et al. Cosibelimab, an anti-PD-L1 antibody: preliminary safety and efficacy results from a global, multicohort phase 1 clinical trial. J Immunother Cancer. 2020;8(suppl 3):A1-A559. doi:10.1136/jitc-2020-SITC2020.0399

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