Eledon Advances Kidney Transplant Drug to Phase III Despite Missing Primary Endpoint in Phase II Trial
Key Insights
Eledon Pharmaceuticals' tegoprubart failed to demonstrate statistical superiority over tacrolimus in preventing kidney transplant rejection (search) but achieved the highest mean eGFR levels reported in kidney transplant clinical trials.
The drug met non-inferiority criteria with a 22% efficacy failure rate compared to 17% for tacrolimus, satisfying FDA's recognized approval endpoint for transplant rejection prevention.
Despite the primary endpoint miss, Eledon plans to advance tegoprubart into Phase III development based on encouraging kidney function preservation data from the BESTOW trial.
Eledon Pharmaceuticals announced mixed results from its Phase II BESTOW trial of tegoprubart, a CD40 ligand-targeting immunosuppressant for kidney transplant rejection (search) prevention, with the company planning to advance the drug into Phase III development despite missing its primary efficacy endpoint.
The BESTOW trial evaluated tegoprubart against tacrolimus, the standard-of-care calcineurin inhibitor immunosuppressant approved by the FDA in 1994, in de novo kidney transplant patients. While tegoprubart failed to demonstrate statistical superiority in the primary endpoint of estimated glomerular filtration rate (eGFR) improvement at 12 months post-transplant, the results showed promise in kidney function preservation.
Primary Endpoint Results Show Non-Significant Difference
The trial's primary efficacy endpoint measured changes in eGFR at 12 months post-transplant. Patients treated with tegoprubart achieved an eGFR of 69 mL/min/1.73 m² compared to 66 mL/min/1.73 m² for those receiving tacrolimus, a difference that did not reach statistical significance.
Despite missing the primary endpoint, Eledon highlighted that the eGFR level observed in the tegoprubart group represents "the highest mean eGFR level reported to date in kidney transplant clinical trials evaluating rejection prevention." The company believes these results, if replicated in Phase III, would support the drug's approvability.
FDA-Recognized Endpoint Shows Non-Inferiority
The trial's secondary endpoints included several clinically relevant measures, with the efficacy failure composite endpoint serving as the FDA's currently recognized approval endpoint for transplant rejection prevention drugs. This composite measure encompasses death, graft loss, and biopsy-proven acute rejection.
Tegoprubart demonstrated non-inferiority to tacrolimus on this critical endpoint, with an efficacy failure rate of 22% compared to 17% for tacrolimus, using a 20% non-inferiority margin. Additional secondary endpoints evaluated included patient and graft survival, donor-specific antibodies, delayed graft function, and new-onset diabetes after transplantation.
Market Response and Phase III Plans
The mixed trial results triggered a significant market reaction, with Eledon's shares falling 59% to $1.65 following the data disclosure. The results were presented during a late-breaking oral session at the American Society of Nephrology's Kidney Week in Houston.
Despite the primary endpoint miss and negative market response, Eledon remains committed to advancing tegoprubart into Phase III development. The company's decision reflects confidence in the drug's potential based on the kidney function preservation data and achievement of non-inferiority on the FDA-recognized composite endpoint.
Targeting CD40 Ligand Pathway
Tegoprubart represents a novel approach to preventing organ rejection by targeting the CD40 ligand pathway, differentiating it from traditional immunosuppressants like tacrolimus. This mechanism of action offers potential advantages in transplant medicine, where balancing immune suppression with preservation of kidney function remains a critical challenge.
The drug's development continues as part of efforts to improve outcomes for kidney transplant recipients, who currently rely on immunosuppressive regimens that have remained largely unchanged since tacrolimus's approval three decades ago.