Date: Monday, June 7, 2021
Session Time: 4:30pm-5:30pm
Presentation Time: 5:00pm-5:05pm
*Purpose: We report interim results of the Phase 3 MERCURY tolerance study, which produces mixed chimerism and ultimately generates operational tolerance allowing for the elimination of all IS therapy. The randomized, multi-center study evaluated the functional immune tolerance in MDR-101 recipients of HLA-matched living donor (LD) kidney transplants as compared to standard of care (SOC) (NCT03363945).
*Methods: Eligible adult, donor/recipient (D/R) pairs of a first kidney allograft from an HLA-identical LD were enrolled and randomized 2:1 to either the Investigational Arm (IA; n=20) or Control Arm (CA; n=10). Donors in the IA received G-CSF for 5 days before undergoing apheresis. The donor peripheral CD34+ and CD3+ cells were processed to produce the MDR product. IA recipients were transplanted and then received ATG conditioning (7.5mg/kg total) and total lymphoid irradiation (TLI) over 10 days, and IS followed by an infusion of MDR-101 on D11. After 180 days of mixed chimerism, IA recipients initiated a 6-month taper of CNI, and were withdrawn from all IS on D365. CA recipients received continuous IS per institutional SOC.
*Results: To date, 30 D/R pairs have been enrolled: 20 pairs randomized to the IA and 10 pairs to the CA. MDR-101 infusion was completed in 16 IA recipients. All 16 IA recipients developed chimerism; 10 IA recipients reached the D365 milestone and completed withdrawal of all IS. Five of 10 recipients later lost chimerism but remain off IS with good graft function without evidence of rejection. There have been no events of GvHD, biopsy-proven acute rejection, dnDSA, opportunistic infection or PTLD. There have been no graft losses or deaths in either group. The median eGFR and SCr at D365 in the IA group were 68.22 mL/min and 1.27 mg/dL, and in the CA group were 61.51 mL/min and SCr 1.31 mg/dL, respectively.
*Conclusions: Of the 16 recipients in the IA, 10 recipients have reached D365 and were successfully withdrawn from IS without subsequent episodes or evidence of rejection. This is the first-ever multicenter study to induce operational tolerance in kidney transplant recipients. Study follow-up continues through two-years post IS withdrawal.
To cite this abstract in AMA style:Kaufman D, Akkina S, Stegall M, Piper J, Gaber AO, Marin E, Busque S, Alonso D, Vera MDe, Shah A, Patel A, Chavin K, Laftavi M, Collette S, Stites E, Mai M, Cooper M, Brennan D. MDR-101-MLK-MERCURY Kidney Transplant Tolerance Study Update [abstract]. Am J Transplant. 2021; 21 (suppl 3). https://atcmeetingabstracts.com/abstract/mdr-101-mlk-mercury-kidney-transplant-tolerance-study-update/. Accessed June 13, 2021.
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