Checkpoint Therapeutics Announces Positive Topline Results from the Registration-Enabling Trial of Cosibelimab in Metastatic Cutaneous Squamous Cell Carcinoma

Checkpoint Therapeutics, Inc. recently announced positive topline results from its registration-enabling clinical trial evaluating the safety and efficacy of its anti-PD-L1 antibody, cosibelimab, administered as a fixed dose of 800 mg every 2 weeks in patients with metastatic cutaneous squamous cell carcinoma (cSCC).

The study met its primary endpoint, with cosibelimab demonstrating a confirmed objective response rate (ORR) of 47.4% (95% CI: 36.0, 59.1) based on independent central review of 78 patients enrolled in the metastatic cSCC cohort using Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) criteria. The median duration of response (DOR) had not yet been reached at the data cut-off point (76% of responses are ongoing). Safety data across 201 patients with advanced cancers enrolled and treated in all cohorts of the ongoing study remain consistent with those previously reported, with the majority of treatment-emergent adverse events reported as Grade 1 or 2 in severity. Based on these results, Checkpoint intends to submit a Biologics License Application (BLA) to the US FDA for cosibelimab later this year, to be followed by a marketing authorization application (MAA) submission in Europe and additional potential submissions in markets worldwide.

“Most people don’t realize that cutaneous squamous cell carcinoma is the second most common form of skin cancer. While treatable with surgery when caught early, cSCC patients diagnosed with advanced disease that has recurred or metastasized have traditionally faced a poor prognosis and often suffer from painful physical discomfort,” commented Professor Philip Clingan, Medical Oncologist at Southern Medical Day Care Centre in Australia and co-principal investigator of the trial. “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.”

James F. Oliviero, President and Chief Executive Officer of Checkpoint, added “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. We extend our sincere thanks to the patients, caregivers, investigators and their site staff for their dedication to this trial, particularly during these challenging times globally. We look forward to a detailed presentation of the data at an upcoming medical meeting.”

Mr. Oliviero continued, “Upon approval, we intend to position cosibelimab at a lower price point than currently available PD-(L)1 therapies, which we hope will lead to meaningful market share in the US and international markets around the world. We also believe the safety and efficacy profile of cosibelimab could make cosibelimab an attractive agent for use in combination regimens, potentially with drug candidates within our current portfolio, additional molecules we may in-license, and synergistic molecules through potential collaborations, particularly those that can take advantage of the two-fold mechanism of action of cosibelimab.”

Additionally, Checkpoint continues to enroll a registration-enabling cohort of patients with locally advanced cSCC, anticipating this potential second indication could be included in the planned initial BLA submission, as well as the global, randomized Phase 3 (CONTERNO) trial of cosibelimab in combination with pemetrexed and platinum chemotherapy for the first-line treatment of patients with non-squamous non-small cell lung cancer.

Cutaneous squamous cell carcinoma (cSCC) is the second most common type of skin cancer in the US, with an estimated annual incidence of approximately 1 million cases according to the Skin Cancer Foundation. While most cases are localized tumors amenable to curative resection, approximately 40,000 cases will become advanced and an estimated 15,000 people will die from their disease. In addition to being a life-threatening disease, cSCC causes significant functional morbidities and cosmetic deformities based on tumors commonly arising in the head and neck region and invading blood vessels, nerves and vital organs such as the eye or ear.

Cosibelimab (formerly referred to as CK-301) is a potential best-in-class, high affinity, fully-human monoclonal antibody of IgG1 subtype that directly binds to programmed death ligand-1 (PD-L1) and blocks the PD-L1 interaction with the programmed death receptor-1 (PD-1) and B7.1 receptors. Cosibelimab’s primary mechanism of action is based on the inhibition of the interaction between PD-L1 and its receptors PD-1 and B7.1, which removes the suppressive effects of PD-L1 on anti-tumor CD8+ T-cells to restore the cytotoxic T cell response. Cosibelimab is potentially differentiated from the currently marketed PD-1 and PD-L1 antibodies through sustained >99% target tumor occupancy to reactivate an antitumor immune response and the additional benefit of a functional Fc domain capable of inducing antibody-dependent cell-mediated cytotoxicity (ADCC) for potential enhanced efficacy in certain tumor types.

Checkpoint Therapeutics, Inc. is a clinical-stage immunotherapy and targeted oncology company focused on the acquisition, development and commercialization of novel treatments for patients with solid tumor cancers. Checkpoint is evaluating its lead antibody product candidate, cosibelimab, a potential best-in-class anti-PD-L1 antibody licensed from the Dana-Farber Cancer Institute, in an ongoing global, open-label, multicohort Phase 1 clinical trial in checkpoint therapy-naïve patients with selected recurrent or metastatic cancers, including cohorts in locally advanced and metastatic cutaneous squamous cell carcinoma intended to support one or more applications for marketing approval. In addition, Checkpoint is evaluating its lead small-molecule, targeted anti-cancer agent, CK-101, a third-generation epidermal growth factor receptor (EGFR) inhibitor, as a potential new treatment for patients with EGFR mutation-positive non-small cell lung cancer. Checkpoint is headquartered in Waltham, MA, and was founded by Fortress Biotech, Inc. For more information, visit www.checkpointtx.com.