Experimental Pig Kidney Transplants Enter Clinical Trials in the U.S.

The Food and Drug Administration has cleared the way for clinical trials involving gene-edited pig kidney transplants, a milestone moment in xenotransplantation designed to tackle the critical shortage of human donor organs.

Transition from Emergency Use to Formal Studies

Earlier this year, Massachusetts General Hospital (MGH) performed a groundbreaking transplantation of a genetically modified pig kidney into a 62-year-old patient under the FDA’s compassionate-use protocol. The organ, featuring 69 genomic edits, functioned successfully post-surgery before the patient passed away from unrelated cardiac complications.

In 2025, two additional living patients received pig kidney xenotransplants. Sixty-six-year-old Tim Andrews became the second person known to live with a pig kidney after surgery in January. He has since remained off dialysis and left the hospital about a week later. More recently, 54-year-old Bill Stewart, from New Hampshire, underwent the procedure on June 14 and is gradually resuming work. He described himself as a “science nerd” and chose the procedure understanding its experimental nature.

FDA Approval Launches Early-Phase Clinical Trial

Based on experiences with these early cases, the FDA granted approval for a formal clinical trial of eGenesis’s lead candidate, EGEN-2784. The study targets patients aged 50 and older with end-stage kidney disease who are on dialysis and awaiting transplant. The trial will assess the pig kidney’s safety, tolerability, and efficacy over a 24-week period post-transplant.

This development marks the first such trial following prior approvals given earlier in 2025 to both eGenesis and United Therapeutics to evaluate pig kidney xenotransplantation in human subjects.

Addressing a Critical Organ Shortage

In the U.S., more than 800,000 people live with end-stage kidney disease, yet only around 28,000 received human kidney transplants in 2024, highlighting a severe supply gap. Dialysis remains their primary option, though it carries high morbidity and mortality over five years.

Dr. Leonardo Riella of MGH, a key figure in the trial, noted that even temporary organ function provided by a pig kidney could offer patients a significant quality-of-life benefit and more time on the waiting list.

The trial will involve up to 30 centers across the nation, with eGenesis and MGH collaborating to scale operations and broaden patient access.

International Progress and Experimental Studies

Parallel advances are occurring abroad. A team in China reported the third known human recipient of a gene-edited pig kidney, a 69-year-old woman who showed encouraging recovery three weeks post-surgery. The same group also conducted a pig liver transplant into a brain-dead human, where the organ functioned, producing bile and albumin for ten days.

Outlook and Considerations

Although the early results are promising, physicians caution that long-term function of pig kidneys in humans remains uncertain. Anti-rejection regimens require ongoing adjustment, and full assessment of efficacy will depend on continued monitoring of clinical trial participants.

These gene-edited xenotransplant procedures represent a potential paradigm shift. They could substantially alleviate organ shortages if proven safe and effective, potentially offering an important alternative for patients facing long waits or ineligibility for human donor organs.

(Rh/Eth/TL/MSM)