Interim phase 1 results have sustained Checkpoint Therapeutics’ hopes for a second indication for its lead anti-PD-L1 antibody.
The drug, cosibelimab, demonstrated a 54.8% objective response rate across 31 patients with locally advanced cutaneous squamous cell carcinoma (SCC) who were not candidates for curative surgery or radiation. This “substantially exceeded” a clinically meaningful lower bound of the 95% two-sided confidence interval of 25%, the company said Thursday.
The drug’s primary mechanism of action is based on the inhibition of the interaction between the protein 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, which Checkpoint licensed from the Dana-Farber Cancer Institute in 2015, already met its primary endpoint in a 78-person study for its lead indication of metastatic SCC, for which an FDA approval submission remains on track for later this year.
The latest interim analysis was designed to incorporated recent feedback from the regulator, with the intention of potentially supporting the addition of a locally advanced SCC indication to the approval application, Checkpoint said.
“We believe the data generated to date continue to show cosibelimab as a differentiated and potentially best-in-class anti-PD-L1 antibody, leveraging a two-fold mechanism of action to deliver robust efficacy with a potentially more favorable safety profile due to its binding to PD-L1 rather than PD-1, an attribute reported in scientific literature as associated with lower rates of severe or worse adverse events as compared to anti-PD-1 therapy,” Checkpoint CEO James Oliviero said in a statement.
“Based on this compelling clinical profile, our planned market-disruptive pricing, and our patent protection through at least 2038, we believe cosibelimab has the opportunity to gain meaningful market share in the $32 billion and growing anti-PD-(L)1 class, while significantly lowering the barrier of high out-of-pocket costs patients endure worldwide to access existing premium-priced cancer therapies."
The news did nothing to nudge up Checkpoint’s share price, which has dropped 76% to $1.02 from a November 8, 2021 high of $4.27.