Regeneron has hit the brakes on the phase 1/2a trial for an experimental eye inflammation treatment, following an adverse event that tilted the drug’s risk/benefit profile in the wrong direction.
The Titan study tested REGN7041, an anti-CD3 monoclonal antibody, in patients with inflammation of the uvea, eye’s middle layer, that is not caused by infection.
“Regeneron voluntarily terminated the Phase 1/2a TITAN study investigating REGN7041 for the treatment of non-infectious uveitis of the posterior segment,” a company spokesperson told Fierce in a statement. “This decision follows an updated risk-benefit assessment for the study treatment, prompted by a thorough review of a safety event observed in the trial.”
The New York pharma has investigated the incident, the spokesperson added, but “the underlying cause has not been identified.”
“Patient safety is Regeneron's top priority,” the spokesperson said. “We will continue to evaluate the data from this study.”
Regeneron did not respond to further questions from Fierce about the nature and severity of the adverse event or the overall status of REGN7041’s development.
CD3 is a proinflammatory protein found on the surface of T cells, with a long history as a drug target—the very first monoclonal antibody ever approved for human use, muromonab, targets CD3. Most development since then has focused on hitting CD3 alongside another target using bispecific antibodies, though Sanofi’s diabetes drug Tzield also only targets CD3.
Regeneron got its first taste of CD3 success in July 2025 with the approval of Lynozyfic for multiple myeloma. Lynozyfic is a bispecific targeting BCMA and CD3, as are its competitors, Johnson & Johnson’s Tecvayli and Pfizer’s Elrexfio.
No anti-CD3 antibodies have been successfully developed for an eye disease, but Immunocore’s bispecific T-cell engager Kimmtrak—which targets CD3 as well as glycoprotein 100—has received an FDA go-ahead for metastatic uveal melanoma.