Summary
By mid-2026, pig-to-human organ transplantation has shifted from highly publicized single-patient “expanded access” procedures to formal, FDA-cleared clinical development programs—most clearly in kidney transplantation, where two U.S. sponsors have IND-authorized studies designed to generate registrational evidence over defined follow-up periods.[1–3] At the same time, compassionate-use kidney and heart cases—and controlled decedent studies—continue to provide mechanistic insight into rejection and inform trial design, including how antibody-mediated rejection (AMR) can emerge weeks after transplantation and how it may be reversed in some settings with targeted immunomodulation and intensive rescue therapy.[4, 5]
How the breakthrough works
Current clinical xenotransplantation relies on donor pigs engineered to reduce immediate immune injury and improve physiologic compatibility, coupled with intensive post-transplant immunosuppression and close infectious-disease monitoring.[2, 3, 6] In the best-documented heart program, “10-gene” donor pigs incorporated three glycan deletions (Gal, SDa, and Neu5Gc), deletion of the pig growth hormone receptor (GHRKO), and multiple human transgenes involved in complement and vascular/coagulation biology (hCD46, hCD55, hTBM, hEPCR, hCD47, hHO-1).[7]
Kidney programs use similar “multi-gene edited” strategies, and the first FDA-cleared kidney trial explicitly describes the graft as a UKidney derived from a “10 gene-edited source pig.”[2] In addition to genetic engineering, some experimental approaches also add thymic tissue to modulate immunity; in one 61-day decedent “thymokidney” study, investigators observed dialysis independence and later AMR, creating a uniquely information-rich window into human anti-xenograft immune kinetics.[4, 5]
Two FDA-cleared U.S. kidney trials now enrolling
The most concrete “clinic-entry” milestone is the start of FDA IND–cleared xenokidney trials intended to prospectively measure safety and function over standardized time horizons.
United Therapeutics reported FDA clearance of an IND to initiate a clinical study of UKidney, explicitly described as being derived from a 10 gene-edited source pig.[2] The company stated the study would enroll an initial cohort of 6 end-stage renal disease (ESRD) participants and expand to as many as 50, and that it is intended to support a Biologics License Application (BLA) with the FDA.[2, 3] The trial is named EXPAND (NCT06878560) and is described as a multicenter, open-label safety-and-efficacy study, “designed as a combination phase 1/2/3 trial (sometimes referred to as a ‘phaseless’ study).”[3] Participants receive a UKidney transplant followed by a 24-week post-transplant follow-up period that includes endpoint and safety assessments, with efficacy endpoints including participant survival, UKidney survival, change in measured glomerular filtration rate, and change in quality of life at 24 weeks post-transplant.[3] Eligibility criteria include ESRD patients deemed ineligible for conventional allogeneic kidney transplant for medical reasons, as well as those who are on the waitlist but “more likely to die or go untransplanted than receive a deceased donor kidney transplant within 5 years.”[2]
In parallel, eGenesis reported FDA clearance of its IND application to initiate a clinical trial evaluating EGEN-2784, described as a genetically engineered porcine-derived kidney, in patients with end-stage kidney disease (ESKD).[1] The IND supports a phase 1/2/3 study assessing safety, tolerability, and efficacy at 24 weeks post-transplant in ESKD patients who are at least 50 years old, dialysis-dependent, and on the kidney transplant waitlist.[1] A separate report also described eGenesis as stating on September 8, 2025 that the FDA cleared its clinical trial.[8]
The table below summarizes what these public sources specify about the two U.S. IND pathways.
Patient outcomes informing the trials
Expanded-access kidney xenotransplantation has produced both encouraging functional outcomes and clear examples of immune-mediated failure.
At Massachusetts General Hospital (MGH), Tim Andrews (67) received an EGEN-2784 kidney on January 25, 2025; eGenesis’ public description reported he surpassed seven months post-transplant and remained dialysis-free.[1] In a separate MGH communication about this procedure, the hospital stated the transplant was performed under the FDA Expanded Access Protocol (commonly called compassionate use) and that Andrews was discharged on February 1 recovering off dialysis for the first time in more than two years, with kidney function “as expected.”[9] Bill Stewart (54) received an EGEN-2784 kidney on June 14, 2025 and was described as no longer requiring dialysis for the first time in more than two years.[1]
Not all outcomes have been durable. Towana Looney (53) received a gene-edited pig kidney at NYU Langone on November 25, 2024; in early follow-up, her team reported close tracking after discharge and described kidney function as “absolutely normal.”[10] NYU Langone later reported that her pig kidney was removed on April 4, 2025 after rejection and that she resumed dialysis.[11]
Peer-reviewed case reporting also underscores that early graft function does not eliminate serious overall risk in this medically complex population. In one published pig kidney xenotransplant case, investigators reported that the xenograft “functioned immediately,” creatinine decreased promptly, and dialysis was no longer needed, but the patient died from unexpected sudden cardiac causes on day 52; autopsy did not show evident xenograft rejection.[12]
Decedent studies have filled key knowledge gaps about timing and mechanisms of rejection. In a 61-day decedent kidney xenotransplant, investigators conducted multi-omics profiling and reported that plasmablasts, NK cells, and dendritic cells rose between postoperative days 10 and 28, preceding biopsy-confirmed AMR at postoperative day 33; they also reported rising human T-cell frequencies peaking between postoperative days 33 and 49, coinciding with combined AMR and cell-mediated rejection at postoperative day 49.[5] In a related 61-day “thymokidney” report, investigators described dialysis independence and an AMR episode at postoperative day 33 that was “completely reversed” using plasma exchange, complement C3/C3b inhibition, and rabbit anti-thymocyte globulin (rATG).[4]
Beyond kidneys
Heart xenotransplantation remains clinically informative but has not yet demonstrated durable survival in the limited expanded-access experience reported to date. The first pig-to-human life-supporting heart xenotransplant was performed on January 7, 2022; the xenograft developed sudden diastolic thickening and failure on day 49, and life support was withdrawn on day 60.[13] Reviews of subsequent experience describe another 10-gene–edited heart transplant on September 20, 2023 in a 58-year-old man who lived for nearly six weeks post-transplant, and they connect abrupt diastolic heart failure in both cases principally to AMR.[7, 14]
Decedent heart studies have also helped establish procedural feasibility while limiting patient risk. At NYU Langone, two heart xenotransplant experiments in decedent recipients were performed on June 16, 2022 and July 6, 2022, with the procedures concluding June 19 and July 9; the group reported no signs of early rejection over three days of monitoring and reported that porcine cytomegalovirus (pCMV) was not detected under a dedicated infectious-diseases protocol.[6]
Outside the U.S., a peer-reviewed auxiliary liver xenotransplant in a brain-dead recipient was reported from Xijing Hospital, using a six-gene-edited pig liver in a heterotopic auxiliary configuration. The recipient was diagnosed with brain death on March 7, 2024, the surgery occurred March 10, 2024, and the study was terminated 10 days later at the family’s request; bile production was documented within two hours of portal vein reperfusion, the xenograft remained functional through study completion, and histology showed no signs of rejection with platelet counts returning to normal after an early decline.[15]
What remains uncertain
Even with IND-cleared trials and encouraging dialysis-free intervals in select recipients, key uncertainties remain about long-term durability, the predictability and management of AMR, and the extent to which decedent and short-duration signals translate into multi-year outcomes in living recipients.[3–5] Infectious-risk control is a second continuing pillar: decedent heart studies highlight the operational importance of pathogen surveillance protocols (for example, pCMV testing), while clinical trials also plan safety monitoring that includes zoonotic and opportunistic infections over time.[3, 6]
Closing
The May 2026 picture is therefore best described as an inflection point: xenotransplantation is no longer confined to isolated, one-off demonstrations, but it is also not yet a routine clinical service. The field’s center of gravity has shifted to prospective U.S. trials with defined cohorts and 24-week endpoints, alongside carefully documented expanded-access cases and mechanistic decedent studies that continue to clarify how and when rejection emerges and can sometimes be reversed.[1, 3–5]
