Tegoprubart's Phase 3 kidney transplant path hinges on whether FDA accepts a non-inferiority safety profile after BESTOW missed its primary efficacy endpoint

Bull

FDA provides guidance that accepts a trial design anchored on a non-inferiority safety profile — specifically reduced thromboembolic risk versus calcineurin inhibitors — combined with a composite or secondary efficacy endpoint that tegoprubart can reasonably achieve. This would validate the regulatory strategy, allow Phase 3 initiation, and reframe the BESTOW miss as a design issue rather than a drug failure, materially de-risking the program and supporting a higher probability of eventual approval.

Bear

FDA declines to accept a safety-based non-inferiority framework as sufficient and requires demonstration of superiority or non-inferiority on a traditional efficacy endpoint such as biopsy-proven acute rejection rates, which tegoprubart failed to achieve in BESTOW. Alternatively, FDA may impose trial design requirements — enrollment size, duration, or endpoint thresholds — that are operationally or financially infeasible for a company of ELDN's scale, effectively halting the kidney transplant program.