INTRO: CAAMR after kidney transplantation (KTx) is associated with rates of allograft failure approaching 50% at 2 years from injury involving T cells, B cells, and donor specific antibodies (DSA). Tocilizumab(TOC) is a monoclonal antibody that inhibitis IL-6, a regulator of T- and B- cell activation, and has been used to desensitize waitlisted patients. We report our experience using TOC in patients(pts) with CAAMR.

METHODS/RESULTS: Since 2015, 20 pts received TOC 8 mg/kg with >3 months follow up added to tacrolimus/mycophenolate/pred for CAAMR refractory to treatment. Mean age at KTx was 37±11.5 years, most were female (16), and received live donor KTx(14). All patients had prior AMR with DSA[mdash]Class I=4, Class II=9, Class I&II= 7 – that persisted despite plasmapheresis(9), IVIG at 2 gm/kg(11), rituximab(5). 16 patients also had prior ACR (borderline=9, 1A=3,1B=3, 2A=1). TOC was started an average 1648±1420 days after transplant, with a starting creatinine-=2.35±0.95, and given an average 323±281 days. In the 3 months prior to initiation of TOC, eGFR declined by 3.9 cc/min each month, compared to 0.05 cc/min each month on TOC(p= 0.008). Proteinuria also stabilized on TOC- initial urine protein:creatinine ratio (UPC) of 1.01(±1.1) vs 0.80 (±1.1) at f/u. Stabilization was not dependent on level or type of DSA, and nor did DSA change significantly during follow up. There were 3 ACRs (2- borderline & 1B=1) and one patient with recurrent AMR after stopping TOC that responded to re-initiation. There were 2 cases of BK viremia (0 nephropathy), 1 EBV viremia, and 1 hospitalization for pneumonia. Only one patient stopped due to infusion related reactions. There was 1 patient with primary nonfunction due to unresolving ATN+AMR and 2 graft failures (1 non-compliance and 1 progressive rejection).

CONCLUSION: CAAMR is difficult to treat and associated with high rates of graft failure. In a group of patients with CAAMR refractory to other treatments, addition of TOC to a regimen of tac/mycophenolate/prednisone stabilized eGFR the majority despite persistent DSA with few infectious complications.

CITATION INFORMATION: Patel S., Mohan S., Fernandez H., Batal I., Ratner L., Crew J. Tocilizumab Stabilizes Renal Function in Kidney Transplant Recipients with Chronic Active Antibody Mediated Rejection (CAAMR) Am J Transplant. 2017;17 (suppl 3).

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