At 18 months, adults given tegoprubart after a first kidney transplant had better-preserved kidney function than those taking tacrolimus, according to results from the phase 2 BESTOW trial. The difference was statistically significant at that point, offering an early sign that a different approach to preventing organ rejection may help transplanted kidneys keep working well.
Preventing rejection is essential after a transplant, but the medicines used to quiet the immune system can also bring difficult side effects. Tacrolimus is the current standard treatment. Andrew Adams, a kidney transplant researcher at the University of Minnesota Medical School and the study’s corresponding author, said it can cause kidney toxicity, high blood pressure, diabetes, tremors and “brain fog.” Tegoprubart is an experimental antibody therapy designed to block CD40L, a pathway involved in communication between immune cells.
In BESTOW, kidney graft function—the performance of the transplanted kidney—stabilized after the first month of treatment and stayed higher in patients taking tegoprubart than in those taking tacrolimus at every reported measurement. The clearest reported difference came at 18 months, when the kidney-function benefit reached statistical significance. The trial involved adults receiving their first kidney transplant; the results do not establish that tegoprubart is ready to replace standard treatment.
A separate analysis looked at how patients said they felt and functioned. Of the 127 people treated in the study, 107 completed treatment through week 52: 51 taking tegoprubart and 56 taking tacrolimus. By that point, people taking tegoprubart reported improvements from their starting scores across all five health-related quality-of-life subscales. Those taking tacrolimus improved on four of the five. Tegoprubart also showed a larger gain on a mental component summary, while its group had a numerically greater drop in total symptom score. The article did not provide the size of those score changes, so the results point to a difference without showing how large patients’ day-to-day benefit might be.
Together, the kidney-function and quality-of-life findings suggest tegoprubart could offer a promising alternative for some transplant patients. But a phase 2 trial is an early stage of testing, and the findings do not prove that the drug prevents rejection as well as or better than tacrolimus, or that it avoids tacrolimus’s side effects. Adams said the therapy might have potential across different types of transplants, though the BESTOW results described here concern kidney recipients.
The findings are scheduled to be presented at ASN Kidney Week 2026, running Oct. 22–25. Further study will be needed to show whether the kidney-function advantage lasts and how the treatment’s benefits and risks compare over time. For patients and transplant teams, the results raise a practical possibility: protecting a new kidney may one day come with a different balance of benefits and side effects.