On July 27, 2023 Checkpoint Therapeutics, Inc. ("Checkpoint") (Nasdaq: CKPT), a clinical-stage immunotherapy and targeted oncology company, reported new, longer-term data for cosibelimab from its pivotal studies in locally advanced and metastatic cutaneous squamous cell carcinoma ("cSCC") (Press release, Checkpoint Therapeutics, JUL 27, 2023, View Source [SID1234633437]). These results demonstrate a deepening of response over time, resulting in substantially higher complete response rates than previously reported. Furthermore, responses continue to remain durable over time with the median duration of response not yet reached in either group. Results determined by independent central review by treatment group were as follows:

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Parametera Locally Advanced cSCC
(n=31) Metastatic cSCC
(n=78)
Data cutoff Mar 2022 Jan 2023 Nov 2021 Jan 2023
Objective response rate
(95% confidence interval) 55%
(36%, 73%) 55%
(36%, 73%) 47%
(36%, 59%) 50%
(39%, 62%)
Complete response rate 10 % 23 % 8 % 13 %
Partial response rate 45 % 32 % 39 % 37 %
Response ongoing 82 % 82 % 73 % 69 %
Median duration of response Not reached Not reached Not reached Not reached
a As assessed by independent central review.

"We are excited to see the substantial increases in the rate of patients experiencing a complete response of their cSCC tumors with further cosibelimab treatment in both our locally advanced and metastatic pivotal trials," said James Oliviero, President and Chief Executive Officer of Checkpoint. "We believe cosibelimab’s strong efficacy and response durability are driven by its unique two-fold mechanism of action in which cosibelimab binds to PD-L1 with sustained high target tumor occupancy to reactivate the body’s T-cell anti-tumor response, with the addition of a functional Fc domain to activate the body’s natural killer immune cells to induce antibody-dependent cell-mediated cytotoxicity of tumor cells, resulting in a powerful one-two punch to eradicate tumors. We expect this dual mechanism of action to benefit not just immunocompetent patients, but also the large number of difficult-to-treat patients with immunosuppressive conditions or taking immunosuppressive medications who continue to suffer poor outcomes with currently available treatments."

Updated safety data across 247 patients enrolled and treated with cosibelimab in all cohorts of the ongoing study remain consistent with those previously reported, with only 2% of patients experiencing a severe immune-related adverse event ("irAE") and less than 1% of patients discontinuing treatment due to an irAE of any severity, both substantially lower than the rates observed with currently approved immunotherapies.

Mr. Oliviero continued, "Unlike PD-1 inhibitors, cosibelimab does not interrupt the body’s PD-1/PD-L2 pathway, which we believe results in cosibelimab’s low rates of autoimmunity. We believe cosibelimab’s favorable safety profile should position the product as the preferred immunotherapy of oncologists for the large number of high-risk cSCC patients, such as those with solid organ transplants or autoimmune disease, upon its potential launch early next year. If our Biologics License Application ("BLA") is approved in the coming months, based on its unique mechanism of action and compelling efficacy and safety profile, we believe cosibelimab, as a differentiated and possibly best-in-class treatment, has the potential to become the market leading immunotherapy for patients with cSCC, which we estimate to be a $1.6 billion annual U.S. market opportunity."

In January 2023, Checkpoint submitted a BLA to the U.S. Food and Drug Administration ("FDA") seeking approval of cosibelimab as a treatment for patients with metastatic cSCC or locally advanced cSCC who are not candidates for curative surgery or radiation. The application is filed and under review with a Prescription Drug User Fee Act ("PDUFA") goal date of January 3, 2024.

Checkpoint plans to present these updated results at an upcoming medical conference.