Cosibelimab induces encouraging response rate in cSCC, justifying BLA submission to FDA

Early results from an international phase 1 study of cosibelimab are encouraging and could lead to the submission of a biologics license application to the FDA.

Cosibelimab Treatment Achieved a Promising Objective Response Rate (ORR) in Patients With Metastatic Squamous Cell Carcinoma Meeting the Primary Endpoint of a Phase 1 Study, Key Results Announced in Press Release Press.1

Cosibelimab (formerly CK-301) is a fully human IgG1 subtype monoclonal antibody that binds to PD-L1 to block the interaction between PD-L1 and B7.1 receptors. By blocking this interaction, the suppressive effects of PD-L1 on anti-tumor CD8-positive T cells are suppressed and the cytotoxic T cell response can be restored.

“We are delighted to announce these initial results from our pivotal trial of cosibelimab in metastatic cutaneous squamous cell carcinoma. We believe that the strong ORR result is attributable to cosibelimab’s differentiated dual 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 the literature to be associated with lower rates of serious or worse adverse events compared to PD-1 therapy. We extend our sincere thanks to the patients, caregivers, researchers and staff at their site for their dedication to this trial, especially during these challenging times globally. We look forward to a detailed presentation of the data at an upcoming medical meeting,” said James F. Oliviero, President and CEO of Checkpoint Therapeutics, in a press release.

In the Phase 1, open-label, multicenter, dose-escalation study (NCT03212404), cosibelimab treatment will be evaluated in approximately 500 patients with advanced cancers including cSCCC, non-small cell lung cancer, colorectal cancer , endometrial cancer, small cell lung cancer, malignant pleural mesothelioma, head and neck squamous cell carcinoma, Merkel cell carcinoma, melanoma, renal cell carcinoma, urothelial carcinoma, Hodgkin’s lymphoma and lymphoma B-cell non-Hodgkin’s.2

The ORR observed with cosibelimab in the CSCc cohort of 78 patients was 47.4% (95% CI, 36.0% – 59.1%), according to an independent central review and according to RECIST v1.1 criteria . The median duration of response (DOR) has not yet been reached and responses were ongoing in 76% of patients.

Safety was assessed in 201 patients in the overall study population. Most treatment-related adverse events observed during the study were grade 1 or 2.

“These impressive results demonstrate that cosibelimab, a novel PD-L1 antibody with a unique 2-pronged mechanism of action, has the potential to offer physicians a novel treatment option that offers compelling efficacy, complemented by a favorable tolerability profile, for patients living with this devastating disease,” said study co-investigator Professor Philip Clingan, Medical Oncologist, Southern Medical Day Care Centre, in a press release.

Based on the positive study results, the company plans to submit a Biologics License Application to the FDA and a Marketing Authorization Application to the European Medicines Agency. It is also possible for the company to submit marketing applications to regulatory bodies around the world.

The study is actively recruiting at 29 centers in Europe, Africa, Australia and Asia. Individuals enrolled in Part 2 of the study will be evaluated for the primary endpoint of ORR and the secondary endpoints of Confirmed Best Overall Response, DOR, ORR, and DOR as per modified RECIST v1.1, overall survival, pharmacokinetics and number of patients with anti-CK-301 antibodies.

To be eligible for inclusion, patients must have histologically or cytologically confirmed advanced cancer, and an ECOG performance status of 0 to 1, at least 1 measurable lesion based on RECIST v1.1, hematological, hepatic and renal function adequate. All patients must use effective contraception throughout the study if there is a risk of conception.

Excluded from the study are patients previously treated with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, anti-CTLA-4 antibody, or any other antibody or drug specifically targeting co -stimulation of T-lymphocytes or immune checkpoint pathway, or who received prior chemotherapy, radiation therapy, cancer biologics, or tyrosine kinase inhibitor therapy within 4 weeks of the study. Patients who have a history of hypersensitivity to other monoclonal antibodies are not eligible to participate in the study, as are those who have already presented with malignancy within the previous 2 years, or those who have a history or active diseases that may interfere with study treatment.

The references:

1. Checkpoint Therapeutics announces the first positive results of the trial enabling the registration of cosibelimab in metastatic cutaneous squamous cell carcinoma. Press release. Checkpoint Therapeutics, Inc. January 25, 2022. Accessed January 31, 2022. https://bit.ly/3gdSFu9

2. Phase 1 study of CK-301 (cosibelimab) monotherapy in subjects with advanced cancers. Clinicaltrials.gov. Accessed January 31, 2022. https://bit.ly/32LD02h

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