Imlifidase in Highly Sensitized Kidney Transplant Recipients With a Positive Crossmatch Against a Deceased Donor.

Introduction: Imlifidase is authorized for desensitization of highly sensitized adult kidney transplant candidates with a positive crossmatch (XM) against a deceased donor. Here, we report on the results for the first 9 patients transplanted in this context who had at least 3 months of follow-up.

Methods: The eligibility criteria were as follows: calculated panel reactive antibodies (cPRA) ³ 98%, ³ 3 years on the waiting list, immunodominant donor-specific antibodies (DSAs) with mean fluorescence intensity (MFI) > 6000 (and < 5000 at 1:10 dilution) and a negative post-imlifidase complement-dependent cytotoxic XM (CDCXM).

Results: All 9 patients had been on dialysis for an average of 123 ± 41 months, with cPRA at 99% ( = 2) or 100% ( = 7). At transplantation, the mean number of DSAs was 4.3 ± 1.4. The median immunodominant DSA MFI was 9153 (6430-16,980). Flow cytometry XM (FCXM) and CDCXM before imlifidase were positive in 9 and 2 patients, respectively. After 1 injection of imlifidase, all were negative. Patients received polyclonal antibodies, i.v. Igs (IVIg), rituximab, tacrolimus, and mycophenolate. Five patients had a DSA rebound within the first 14 days: 2 had concomitant clinical antibody-mediated rejection (ABMR), 2 had subclinical ABMR, and 1 had isolated positive C4d staining. No ABMR was observed in patients without rebound. Chronic Kidney Disease-Epidemiology Collaboration formula estimated glomerular filtration rate (eGFR) was 56 ± 22 ml/min per 1.73 m at the last follow-up (7 ± 2.8 months). No graft loss or death were observed. Four patients developed at least 1 infection.

Conclusion: These real-life data demonstrate that the use of imlifidase to desensitize highly sensitized patients can have an acceptable short-term efficacy and safety profile in selected patients.