Imlifidase in Living Donor Renal Transplantation Highly Sensitized Recipients

This is a Phase II, pilot, prospective, unicentric trial, to evaluate Imlifidase could improve the transplantability of the highly sensitized patients with good outcomes respect to survival and functionality of the graft.

The patients between 18 and 65 years will be flow cytometry crossmatch (FC-XM) positive against an available living donor. The imlifidase treatment will turn the crossmatch test negative prior to transplantation. A second dose of imlifidase can be given within 24 hours if the first dose is considered not to have sufficient effect. If a second dose is given, a confirmatory FCXM test will be performed pre-second imlifidase dosing and between 2-6 hours following the second dose.

Eligibility Criteria:
Inclusion Criteria:Inclusion Criteria To be eligible to participate in this study, candidates must meet the following elegibility criteria. Currently, at the Hospital Clinic of Barcelona, up to 10 highly sensitized patients would meet the following inclusion criteria.

* Participant Inclusion Criteria
* Sensitized (cPRA ≥ 50%) kidney transplant candidates between 18 and 65 years.
* Low probability to get a transplant in a kidney exchange program (KEP) from a living donor.
* Included in the living donor program, with an accepted potential living donor.
* Donor and recipient must meet the eligibility criteria for donation and kidney transplantation respectively at the Hospital Clinic of Barcelona and the national guidelines.
* Presence of donor-specific antibody/crossmatch positive (DSA/FC-XM+) non-HLA identical donor.

  * at least one DSA with MFI \>3.000.
  * and DSA MFI \<10.000 (in serum samples diluted 1/64).
  * and maximum two Class II DSAs.
  * and maximum 17 points in Jordan RIS Score (DSA 2500-5000: 2 points; DSA MFI 5001-10000: 5 points; DSA MFI \> 10000: 10 points)
* Women of childbearing age must take contraceptive measures because Imlifidase is not recommended during pregnancy.
* Must have given written informed consent (signed and dated) and any authorizations required by local law and be able to comply with all study requirements.

Exclusion Criteria

Participants who meet any of the following criteria will be excluded from participation in this study:

• Participant Exclusion Criteria

1. Known contraindications for therapy with IVIG, Rituximab, plasma exchange (PLEX) or Imlifidase.
2. Recipients of Deceased Donors (DBD, Extended Criteria Donors (ECD) or DCD).
3. A positive Complement-Dependent Cytotoxicity (CDC) Crossmatch against the living donor.
4. HIV-positive subjects.
5. Subjects who test positive for HBV infection \[positive HBVsAg or HBVeAg/DNA\] or HCV infection \[RNA+\].
6. Subjects with active TB.
7. Subjects with selective IgA deficiency, those who have known anti-IgA antibodies, and those with a history of anaphylaxis or severe systemic responses to any part of the clinical trial material.
8. Subjects who have received or for whom multiple organ transplants are planned.
9. A significantly abnormal general serum screening lab result defined as WBC\<3.0x103/ml, Hgb\<8.0 g/dL, platelet count \<100x103/ml, SGOT\>3xupper limit.
10. Subjects with active CMV or EBV infection as defined by positive PCR.
11. Subjects with a known history of previous myocardial infarction within one year of screening.
12. Subjects with a history of clinically significant thrombotic episodes, and subjects with active peripheral vascular disease.
13. Patients with a kidney disease with high risk of recurrence and/or complement-associated kidney disease (aHUS, etc).
14. Subjects with Protein C and Protein S deficiency.
15. Pregnant and lactating women
16. Current diagnosis or history of thrombotic thrombocytopenic purpura (TTP), or known familial history of TTP.
17. Known allergy to Imlifidase or excipient of the drug preparation