Preliminary safety and efficacy data presented at ESMO 2020 Virtual Congress demonstrate that cosibelimab has a manageable safety profile and meaningful clinical activity in patients with metastatic cutaneous squamous cell carcinoma (mCSCC).

“Cosibelimab is a high affinity, fully-human IgG1 monoclonal antibody that directly binds to [PD- L1] and blocks its interaction with the [PD-1] and B7.1 receptors to restore an anti-tumor immune response,” wrote Philip Clingan, MD, Southern Medical Day Care Centra, Wollongong, Australia and co-investigators on the rationale of the trial.

Researchers added that cosibelimab has the additional benefit of a functional Fc domain capable of inducing antibody-dependent cellular cytotoxicity against tumor cells.

Study CK-301-101 is a global, multi-center, multi-cohort trial enrolling patients with select advanced cancers. Preliminary safety data from the trial and efficacy data from the metastatic cutaneous squamous cell carcinoma (mCSCC) cohort were presented at the 2020 ESMO Virtual Congress.

As of April 2020, 103 patients partaking in the study have been treated with cosibelimab. Eligible mCSCC patients received a 800mg dose of cosibelimab intravenously every two weeks.

The primary efficacy endpoint was objective response rate (complete + partial response, by independent central review). Objective response rate was 47% (n = 15) in 32 mCSCC patients evaluable for response, including 3 complete responses and 12 partial responses. Median duration of response was not reached at the time of analysis with 14/15 (93%) responses ongoing.

The safety analysis reporting included all patients treated with at least one dose of cosibelimab. Of 103 treated patients, 92% experienced grade ≥1 treatment-emergent adverse events (AE); 36% experienced grade ≥3 AEs; 6% have experienced grade ≥3 drug-related AEs. Fatigue, anemia, nausea and rash were the most common treatment-emergent AEs. The most common drug-related AEs were rash and fatigue.

“Cosibelimab has a predictable and manageable safety profile and demonstrated robust clinical activity in mCSCC patient, including durable complete and partial responses,” Dr Clingan et al concluded.

Enrollment in the trial is still ongoing.—Kaitlyn Manasterski

Clingan P, Brungs D, Ladwa R, Mant A.M. Cosibelimab, an anti-PD-L1 antibody, in metastatic cutaneous squamous cell carcinoma (mCSCC): Preliminary safety and efficacy results from a phase I clinical trial. Presented at: the ESMO Virtual Congress 2020; September 19-21, 2020; virtual. Abstract 1084P.