Seyltx Secures Option to License GluN2B Antagonists from NeurOp

Seyltx, a clinical-stage biotherapeutics company based in Cambridge, Massachusetts, has announced an option agreement to license a portfolio of eight GluN2B antagonists from Atlanta-based NeurOp. One of the compounds included in the agreement has already completed a Phase 1 clinical trial. All eight compounds are negative allosteric modulators of the GluN2B subunit of the NMDA receptor.
Preclinical studies have identified GluN2B as a key target for cough suppression, and the licensing option gives Seyltx access to a range of candidates designed to act on this specific subunit. The agreement is positioned to align Seyltx’s chronic cough development efforts with NeurOp’s specialization in NMDA receptor biology.

Seyltx is currently advancing Ifenprodil, a GluN2B-selective NMDA receptor antagonist, as its lead therapy. A Phase 2 study in 2022 reported a statistically significant reduction in coughing. Dietrich Stephan, Ph.D., CEO of Seyltx, stated that the agreement with NeurOp expands the company’s chronic cough pipeline and provides new opportunities to deliver non-narcotic treatment options for conditions such as chronic cough and idiopathic pulmonary fibrosis.
The companies expect to finalize a global license agreement covering the eight compounds within the next 12 months. Financial terms related to the deal have not been disclosed.
NeurOp’s executive chairman, James McNamara, M.D., commented that the agreement reflects the company’s scientific development of GluN2B antagonists and noted that Seyltx is well-positioned to advance these compounds further.
The companies referenced dextromethorphan, a commonly used NMDA receptor antagonist, as a comparison point. Their focus is on selectively targeting the GluN2B subunit, with the goal of achieving meaningful cough suppression while reducing side effects typically associated with broader-acting NMDA antagonists.

In connection with the agreement, Seyltx also released preclinical results for Ifenprodil, which will be presented at the American Cough Conference on June 7, 2025. Findings from non-human primate receptor occupancy studies suggest that increasing the dose from 20 mg to between 40 mg and 80 mg in Phase 2 trials could enhance cough suppression prior to reaching receptor saturation.
Additional preclinical data in the guinea pig model showed up to a 74% reduction in cough frequency from baseline with oral dosing, while remaining under the No Observed Adverse Effect Level (NOAEL). The results support a three-times-daily dosing regimen and indicate potential for a once-daily formulation in the future.