SUCCESSFUL LONG-TERM TMA- AND REJECTION-FREE SURVIVAL OF A KIDNEY XENOGRAFT WITH TRIPLE XENOANTIGEN KNOCKOUT PLUS INSERTION OF MULTIPLE HUMAN TRANSGENES

Abstract

Usage of porcine organs is a potential solution to the shortage of organs for transplantation. However it continues to be hindered by multiple immunologic barriers. Recent advances in genome engineering technology allow for the generation of porcine organ donors with multiplex gene edits. Here we evaluated survival of kidneys from triple xenoantigen knockout pigs that contain multiple human transgenes (Pig 2.0) in a life-sustaining non-human primate renal xenotransplant model. Cynomolgus macaques received kidneys from either GTKO.hCD55 pigs (n=2; reference group) or Pig 2.0 (n=8) followed by bilateral native nephrectomy. All Pig 2.0 donors were triple antigen knockout and expressed human complement, inflammation, and immune regulatory transgenes at different levels in three variations (Pig 2.5, 2.9, 2.10). Recipients were treated with anti-rhesus ATG and anti-CD20 mAb as induction, followed by weekly anti-CD154 (hu5C8), daily mycophenolate mofetil (MMF) and, in the reference and 2.9 groups, methylprednisolone and short-term sirolimus. Animals were followed clinically with lab tests, serial ultrasound and protocol biopsies. Regardless of gene modifications, graft survival clustered into three patterns – rapid rejection within three weeks (n=4), delayed rejection at two months (n=3), and longer-term surviving where the animals were euthanized for non-rejection related complications (n=2). One animal remains on study at day 69 without evidence of rejection on his first protocol…