Checkpoint Therapeutics Resubmits Cosibelimab Biologics License Application

Checkpoint Therapeutics, Inc., a clinical-stage company specializing in immunotherapy and targeted oncology, revealed on July 2, 2024, that it has resubmitted its Biologics License Application (BLA) for cosibelimab to the U.S. Food and Drug Administration (FDA). Cosibelimab is an anti-PD-L1 antibody aimed at treating patients with metastatic or locally advanced cutaneous squamous cell carcinoma (cSCC) who are ineligible for curative surgery or radiation.

The resubmission comes after Checkpoint Therapeutics and the FDA reached a consensus on the BLA resubmission strategy. This approach aims to address the deficiencies highlighted in a complete response letter (CRL) received last December. The FDA's concerns were solely related to issues found during an inspection of Checkpoint's third-party contract manufacturing organization (CMO), without any objections to the clinical data, safety, or labeling of cosibelimab.

Checkpoint's resubmission is bolstered by data from studies focusing on recurrent or metastatic cancers, particularly pivotal cohorts in metastatic and locally advanced cSCC. Published data from October 2023 in the Journal for ImmunoTherapy of Cancer showcased the safety and efficacy results from the metastatic cSCC cohort. Furthermore, in July 2023, long-term data indicated an improvement in response rates over time, with a 55% objective response rate and a 26% complete response rate in locally advanced cSCC, and a 50% objective response rate and a 13% complete response rate in metastatic cSCC.

Cosibelimab is distinguished as a high-affinity, fully-human monoclonal IgG1 antibody. It works by binding to PD-L1, inhibiting its interaction with PD-1 and B7.1 receptors. This mechanism restores the cytotoxic T-cell response by removing PD-L1's suppressive effects on anti-tumor CD8+ T-cells. The potential differentiation of cosibelimab from existing PD-1 and PD-L1 antibodies lies in its sustained high tumor target occupancy, which reactivates the antitumor immune response. Additionally, its functional Fc domain may enhance efficacy through antibody-dependent cell-mediated cytotoxicity (ADCC).

Checkpoint Therapeutics, headquartered in Waltham, MA, is devoted to developing and commercializing innovative treatments for solid tumor cancers. Their lead product, cosibelimab, is being evaluated for recurrent or metastatic cancers, including cSCC. Another key candidate is olafertinib, a third-generation epidermal growth factor receptor (EGFR) inhibitor, aimed at treating EGFR mutation-positive non-small cell lung cancer. The company was founded by Fortress Biotech, Inc.

Checkpoint's initiatives represent a significant advancement in cancer treatment, particularly for patients with limited options. If approved, cosibelimab could offer a new therapeutic avenue for cSCC, leveraging a robust mechanism of action to enhance anti-tumor immunity and potentially improve patient outcomes.