FDA Approval Sought for Cosibelimab as cSCC Treatment

A biologics license application has been submitted to the FDA for the approval of cosibelimab (formerly CK-301) for patients with metastatic cutaneous squamous cell carcinoma (cSCC) or locally advanced cSCC who are not candidates for curative surgery or radiation.¹

Submission of the application is based on positive efficacy and safety data from an ongoing, registrational phase 1 trial (NCT03212404) examining fixed doses of cosibelimab given at 800 mg every 2 weeks or 1200 mg every 3 weeks.

The trial is evaluating patients with selected recurrent or metastatic cancers, including metastatic and locally advanced cutaneous squamous cell carcinoma.

“This is a major milestone for Checkpoint Therapeutics, representing our first submission of a marketing application for one of our investigational medications and furthering our evolution from a development-stage company to a fully integrated commercial organization to support the potential launch of cosibelimab,” said James Oliviero, president and chief executive officer of Checkpoint Therapeutics, in a press release.

Cosibelimab is an investigational anti-PD-L1 antibody. The potential best-in-class, high affinity, fully humanized monoclonal antibody of IgG1 subtype binds to PD-L1, allowing it to inhibit the PD-L1 interaction with the PD-1 and B7.1 receptors. This then removes the suppressive effects of PD-L1 on anti-tumor CD8+ T cells to restore the cytotoxic T-cell response.

What sets cosibelimab apart from current PD-1 and PD-L1 antibodies is that it has greater than 99% target tumor occupancy to reactivate an antitumor immune response. Further, it has a functional Fc domain which can induce antibody-dependent cell-mediated cytotoxicity for enhanced efficacy in certain tumor types.

“Cutaneous squamous cell carcinoma is the second most common type of skin cancer in the United States. While most cases involve localized tumors amenable to curative resection, approximately 40,000 cases will become advanced, and an estimated 15,000 people will die from their disease each year. Based on its compelling and differentiated product profile and the positive data generated to date, we believe cosibelimab has the potential to be an important treatment option for patients,” added Oliviero.

Previously in January 2022,the metastatic cutaneous squamous cell carcinoma cohort of the phase 1 trial met its primary end point. Findings showed that among the 78 patients assed, there was a confirmed objective response rate (ORR) of 47.4% (95% CI, 36.0%-59.1%) per independent central review (ICR) using RECIST v1.1 criteria.

Then in June 2022, Checkpoint Therapeutics, Inc. announced updated, positive interim findings from the cohort of patients with locally advanced cutaneous squamous cell carcinoma. Treatment with cosibelimab led to a confirmed ORR of 54.8% (95% CI, 36.0%-72.7%) for the 31 patients per IRC, which exceeded the clinically meaningful lower bound of the 95% 2-sided confidence interval of 25%.

In this first in human, multicenter, open-label, dose-escalation, phase 1 trial, investigators are evaluating the safety, tolerability, and efficacy of intravenous cosibelimab alone in patients with select recurrent or metastatic cancers.²

Three periods will make up the duration of the study, including screening for up to 28 days, treatment for 28-day cycles, and follow-up for up to 6 months with survival follow-up for select cohorts. After the dose-escalation portion, additional evaluable subjects may be included within the trial to further assess end points.

Patients aged 18 years and older are eligible for enrollment in the trial if they have an ECOG performance status of 0-1, an estimated life expectancy of at least 3 months, at least 1 measurable lesion based on RECIST 1.1., provided a formalin fixed tumor tissue sample from a biopsy of a tumor lesion at the time of or after the diagnosis of metastatic disease, adequate hematological, hepatic, and renal function, and agree to use effective contraception throughout the duration of the study.

The primary end points of the trial are confirmed ORR, dose limiting toxicities, and number of patients with treatment-emergent adverse events. Secondary end points of the trial include confirmed best overall response, duration of response, overall survival, safety, and pharmacokinetics.

“Importantly, we continue to plan for cosibelimab to be positioned, upon regulatory approval, as potentially the first and only price disruptive PD-1/PD-L1 inhibitor in the [United States] market. We want to thank the patients and their families, as well as the physicians and their research teams, who participated in our trial and contributed immensely to the advancement of cosibelimab,” Oliviero concluded.

REFERENCES:

1. Checkpoint Therapeutics submits biologics license application to FDA for cosibelimab as a treatment for patients with metastatic or locally advanced cutaneous squamous cell carcinoma. News release. Checkpoint Therapeutics, Inc. January 4, 2023. Accessed January 5, 2023. https://yhoo.it/3WONWmw

2. Phase 1 study of CK-301 (cosibelimab) as a single agent in subjects with advanced cancers. ClinicalTrials.gov. March 4, 2022. Accessed January 5, 2023. https://clinicaltrials.gov/ct2/show/NCT03212404