*Purpose: Selective targeting of effector/memory T cells as induction immunosuppression has been discussed in kidney transplantation. Confidence-interval-estimation study may help to estimate range of the population treatment effect when planning phase III trials.

*Methods: This is a phase II international multicenter open-label single-arm confidence-interval-based clinical trial of BioDrim EU consortium aimed at assessing the clinical efficacy and safety of an induction with rATG (Thymoglobuline) and infliximab (NCT04114188). 67 adult first kidney transplant recipients at low risk (PRA<20%, no DSA) received rATG (2x1.5 mg/kg, POD 0 and 1) and infliximab (5 mg/kg, POD 2) as induction followed by tacrolimus/steroids (no MMF) for 12 months. The efficacy failure was primary endpoint defined as composite of acute rejection, graft loss or poor graft function (eGFR<40ml/min) at 12 months. Alloreactive ELISPOT and other biomarkers were among secondary endpoints.

*Results: Primary endpoint was reached in 23 out of 67 (34.33%, upper-bound of a one side 95%CI=45.01%) at 12-month follow-up. This result fulfills the predefined criteria of efficacy failure of <40% with an upper-bound of the exact one-sided 95%CI<50%. 79.1% patients remained on the study protocol and in 55.2% infections were reported at M12. Patients number with positive pretransplant allo-ELISPOT was higher in patients with primary endpoint (p=0.026).

*Conclusions: We observed a clear efficacy signal of the rATG and infliximab induction regimen in low risk primary kidney transplant recipients. Thus, a progression into a larger superiority design trial is justifiable.

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