On September 16, 2024 Checkpoint Therapeutics, Inc. ("Checkpoint") (Nasdaq: CKPT), a clinical-stage immunotherapy and targeted oncology company, reported the presentation of longer-term data from its pivotal trial of cosibelimab, its anti-programmed death ligand-1 ("PD-L1") antibody, in locally advanced and metastatic cutaneous squamous cell carcinoma ("cSCC") during the European Society for Medical Oncology ("ESMO") Congress 2024, which is taking place in Barcelona, Spain, from September 13 to 17, 2024 (Press release, Checkpoint Therapeutics, SEP 16, 2024, View Source [SID1234646646]).

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Poster Presentation Title: Cosibelimab in Advanced Cutaneous Squamous Cell Carcinoma (CSCC): Longer-term Efficacy and Safety Results from Pivotal Study

"These longer-term results for cosibelimab presented at the ESMO (Free ESMO Whitepaper) Congress demonstrate a deepening of response over time, with higher objective response and complete response rates than initially observed at the primary analyses, and continue to expand the evidence supporting the efficacy and safety of cosibelimab as a potential new treatment for advanced cSCC," said James Oliviero, President and Chief Executive Officer of Checkpoint. "We look forward to our upcoming December 28, 2024, Prescription Drug User Fee Act ("PDUFA") goal date for our Biologics License Application for cosibelimab, and believe, if approved, cosibelimab’s dual mechanisms of action and safety profile may position the product, over time, as the preferred immunotherapy of U.S. oncologists."

Data highlights include:

Efficacy

With 16 months of additional follow-up since the primary analysis, cosibelimab demonstrated increasing objective response rates ("ORRs") and complete response rates per independent central review in 109 patients with advanced cSCC.
ORRs of 54.8% and 50.0% achieved in locally advanced and metastatic cSCC, with median follow-up durations of 24.1 and 29.3 months, respectively.
Results demonstrate a deepening of response over time, with complete response rates of 25.8% and 12.8% in locally advanced and metastatic cSCC, respectively.
Clinically meaningful durations of response ("DOR") were observed, with median DORs not yet reached in either group.
Safety

Overall, in 192 advanced cSCC patients treated with cosibelimab, a manageable safety profile was observed, with notable low rates of treatment-emergent adverse events ("TEAEs"), severe immune-related adverse events ("irAEs"), and treatment discontinuations.
3.6% of patients experienced an irAE assessed as grade 3, with no observed grade ≥4 irAEs.
No events of grade ≥3 pneumonitis, colitis, hepatitis, nephritis, or endocrinopathies.
Treatment discontinuation due to TEAEs, regardless of attribution, was observed in 12 patients (6.3%); the most common reason was COVID-19/COVID-19 pneumonia (1.6%).
A copy of the poster can be found on the Publications page of the Checkpoint Therapeutics website.

In December 2023, the U.S. Food and Drug Administration ("FDA") issued a complete response letter ("CRL") for the cosibelimab Biologics License Application ("BLA") for the treatment of patients with metastatic or locally advanced cSCC who are not candidates or curative surgery or radiation. The CRL only cited findings that arose during a multi-sponsor inspection of Checkpoint’s third-party contract manufacturing organization ("CMO") as approvability issues to address in a resubmission. In July 2024, Checkpoint announced it had completed a resubmission of the BLA to the FDA for cosibelimab to potentially address the approvability issues cited in the CRL. The resubmission was accepted by the FDA as a complete response and the FDA has set a PDUFA goal date of December 28, 2024.

About Cutaneous Squamous Cell Carcinoma (cSCC)
Cutaneous Squamous Cell Carcinoma is the second most common type of skin cancer in the United States, with an estimated annual incidence of approximately 1.8 million cases according to the Skin Cancer Foundation. Important risk factors for cSCC include chronic ultraviolet exposure and immunosuppressive conditions. 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 this disease each year. 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. The immune-suppressed population represents a challenging target in the treatment of advanced cSCC, as they present with a more aggressive disease and with a higher risk of developing immune-related toxicities from checkpoint inhibitor treatment.

About Cosibelimab
Cosibelimab is a potential differentiated, high affinity, fully-human monoclonal antibody of IgG1 subtype that directly binds to 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 high tumor target occupancy of PD-L1 to reactivate an antitumor immune response and the additional potential benefit of a functional Fc domain capable of inducing antibody-dependent cellular cytotoxicity ("ADCC") for potential enhanced efficacy.