Pig Kidneys Got Two Men to Human Transplants After Failing

Two men who received gene-edited pig kidneys have now received human kidneys after the animal organs failed. The sequence is the first of its kind in a living patient, and it still used a scarce human organ.

Tim Andrews of Concord, New Hampshire, lived 271 days off dialysis with a pig kidney, then spent 82 days back on the machine before a human organ arrived on January 13, 2026. A second man later made the same crossing. The pig kidney was a pause, not a replacement.

271 Days, Then 82 More on Dialysis

On January 25, 2025, surgeons at Massachusetts General Hospital put a gene-edited pig kidney into Andrews, then 66, under an FDA expanded-access program. He had type 2 diabetes and end-stage kidney disease, and he had been on dialysis for more than two years after a heart attack in 2023. His blood type was O, which the company that made the organ put at a 5 to 10 year wait, with a 9 percent chance of a donor kidney within five years and a 49 percent chance of leaving the list because of illness or death.

The kidney came from a Yucatan miniature pig named Wilma, produced by eGenesis of Cambridge, Massachusetts, as product EGEN-2784. The animal carried 69 gene edits: three pig sugar markers removed so the human immune system would not attack at once, seven human genes added, and pig retroviruses switched off. Urine started in the operating room. Andrews left the hospital on February 1 and later threw out a first pitch at a Boston Red Sox game.

Leonardo Riella, medical director for kidney transplantation at the hospital, and lead surgeon Tatsuo Kawai ran the case. A biopsy on day 14 showed T-cell rejection, which drugs reversed. Around six months, a bacterial infection that did not come from the pig led the team to cut immunosuppression. Small-vessel injury followed, then tiny clots, then graft failure. Surgeons took Wilma out on October 23, 2025.

ANDREWS FROM PIG KIDNEY TO HUMAN KIDNEY

1. January 25, 2025: Receives the EGEN-2784 pig kidney at Massachusetts General Hospital.
2. February 1, 2025: Leaves the hospital and stays off dialysis.
3. Day 14: A biopsy shows T-cell rejection, which treatment reverses.
4. About six months: Infection forces a cut in anti-rejection drugs; vessel damage begins.
5. October 23, 2025: The pig kidney comes out after 271 days.
6. January 13, 2026: A deceased-donor human kidney goes in, 82 days later.

The human graft worked at once. Through 231 days of follow-up, ending about September 1, 2026, doctors found no new antibodies against human tissue and no pig infection. Riella’s team published that clock as a first-in-human study in The Lancet on September 3, 2026. Andrews has said of the pig kidney, “She was the bridge so that I didn’t die, so I got to the human kidney.” He also said he swims, rides a bike, and enjoys life again.

A genetically modified pig kidney kept a man off dialysis for nine months before a successful human kidney transplant, according to a world-first report in The Lancet.

Read now: https://t.co/CuCrqd9lJD pic.twitter.com/H7mzuRXvuW

— The Lancet (@TheLancet) September 8, 2026

David Mulligan, a professor emeritus of surgery at the Yale School of Medicine who was not on the team, put the gap in plainer terms. Technically, he said, the pig kidney did not serve as a bridge to the human transplant, because dialysis sat in the middle; it did carry most of the waiting time. That is the part that drops out of a 271-day headline.

Bill Stewart Also Reached a Human Kidney

eGenesis said on September 3 that five patients have received EGEN-2784 kidneys at Mass General Brigham since March 2024. Three lived more than eight months without dialysis. One has gone more than nine months and is still on the pig kidney. Two later received human donor kidneys, the first reported hand-offs of that kind.

Bill Stewart, a 54-year-old athletic trainer from Dover, New Hampshire, got his pig kidney on June 14, 2025, and lived with it 250 days. He described fluid retention and anemia so draining that he planned his day around naps. He recalled the team telling him it was time to take the organ out after signs of micro-rejection. He later received a human kidney. Mike Curtis, president and chief executive of eGenesis, has treated the two hand-offs as the point of the update.

These patient outcomes provide important evidence that genetically engineered organs may provide sustained kidney function and dialysis independence while preserving the opportunity for a subsequent human transplant.

Mike Curtis, Ph.D., president and CEO, eGenesis, September 3, 2026 press statement

Curtis has also said the company does not now see a downside to a pig kidney followed by a human one, a fear that hung over the first cases because a pig graft might have primed the immune system against a later human organ. In Andrews, anti-HLA antibodies did not change.

THE FIVE EGENESIS KIDNEYS AT MASS GENERAL

All five cases ran under expanded access, a pathway for people with no good alternative, not under the company’s planned registration trial. The human kidneys that Andrews and Stewart later received still came from the ordinary deceased-donor pool.

The Graft Failed Without Classic Rejection

The Lancet paper is as much a failure report as a success story. Early T-cell rejection in Andrews was treatable. Late failure was not. After the drug cut, biopsies showed inflammation in tiny vessels and then thrombotic microangiopathy, a pattern of clots in small blood vessels. Tissue analysis found macrophages and natural killer cells, with little T-cell activity. The donor-specific crossmatch stayed negative, which argues against the textbook antibody attack transplant teams know how to reverse.

Riella’s group wrote that the case shows a pig kidney can support a person for months and then come out without blocking a later human transplant and without passing a pig pathogen. They also wrote that it shows remaining problems, including late injury that does not look like ordinary rejection. The pig kidney in Andrews did not quietly age out. It failed while doctors were treating an infection, which is the bind every heavily immune-suppressed patient already knows.

eGenesis lists three classes of edits in EGEN-2784: knock out the three glycan antigens that trigger hyperacute rejection, insert seven human transgenes meant to calm immune attack, clotting, and complement, and inactivate endogenous retroviruses. Those edits got Andrews to 271 days. They did not get him to a durable pig organ. Muhammad Mohiuddin of the University of Maryland, who was not involved, has described the near-term goal as keeping a patient alive long enough to reach a human organ, while destination use, a pig kidney that stays, remains the longer bet.

95,492 People Are Still Waiting for a Kidney

Federal transplant data as of July 30, 2026, show 95,492 people waiting for a kidney. Kidneys account for 85 percent of the entire U.S. organ waitlist. In 2025, surgeons performed 27,574 kidney transplants. A bridge that later consumes a deceased-donor kidney does not add an organ to that math. It changes who is healthy enough to be there when one is offered.

THE U.S. KIDNEY WAITING LIST

• 95,492 waiting: People listed for a kidney as of July 30, 2026, per HRSA figures drawn from OPTN data.
• 27,574 transplanted in 2025: Kidney grafts from living and deceased donors in the last full year in that dataset.
• 85 percent of the list: Share of waitlisted people who need a kidney rather than another organ.
• Five pig kidneys: eGenesis grafts placed at one hospital system since March 2024.

Andrews went into the pig operation saying the work was for people on dialysis, a group he put at 500,000. The two men who crossed to human organs are doing well, and that is not a small thing for them. It is a small thing for the list. Expanded access at Massachusetts General Hospital selected patients who could get to Boston, pass a research-ethics screen, and live through a second major operation when the pig kidney quit.

WHAT THE PIG KIDNEY STILL CANNOT DO

• Last as a destination organ: Andrews’s graft failed at 271 days, and Stewart’s came out at 250 days.
• Skip dialysis entirely: Andrews spent 82 days back on the machine between the two transplants.
• Grow the human organ pool: Both men later received deceased-donor kidneys from the same list everyone else uses.
• Move beyond one center: All five eGenesis kidney cases so far have run at Mass General Brigham under expanded access.

If pig kidneys become a standard pause for people who can enroll at a handful of academic centers, the scarce human kidney still goes to whoever survived that pause. People who never get a pig graft, including many already listed far from Boston, remain on the original clock.

A Woman’s Pig Kidney Is Still Working

The living record is no longer Andrews. eGenesis said on September 3, 2026, that one patient has gone more than nine months without dialysis on an EGEN-2784 kidney, a new mark for a gene-edited pig kidney, and remains on the study. Hospital photos and later accounts identify that patient as a woman transplanted at Massachusetts General. Science, writing the next day, compared any such mark with Edith Parker, a Louisiana teacher who lived 274 days with a chimpanzee kidney in 1964 and then died.

The FDA has cleared eGenesis to run RESTORE, a Phase 1/2/3 trial of EGEN-2784 in 33 people with kidney failure who are 50 to 70 years old and already waitlisted for a human kidney. The company said it expects to start that study in the first quarter of 2027 and to keep doing expanded-access transplants in the meantime. Riella, the principal investigator, said the dialysis-free stretches are encouraging and that later human transplants show the approach can leave future options open. That is the modest claim the data support. The larger claim, a pig kidney that ends the wait, is the 2027 trial’s job, not this case series.

United Therapeutics, which makes a separate line of gene-edited pig organs, has already opened its own kidney study and has said it will add more. The field is no longer a single-hospital stunt. It is also not a product on a hospital shelf. Age 50 to 70, waitlisted, dialysis-dependent: those RESTORE gates still leave out children, many older patients, and people who never make the list.

Early Recipients Died of Heart Trouble

Richard Slayman of Weymouth, Massachusetts, was the first living person to receive an EGEN-2784 kidney, in March 2024 at the same hospital. The graft made urine and got him off dialysis. He died 52 days after the pig kidney of sudden cardiac causes. Autopsy showed severe coronary disease and ventricular scarring, without clear rejection of the pig organ. Lisa Pisano, who received a United Therapeutics pig kidney at NYU Langone in 2024, also died within months of heart trouble. The organs can work while the rest of a dialysis-damaged body does not.

Towana Looney lived 130 days with a pig kidney at NYU Langone before it was removed in April 2025. A gene-edited pig kidney placed in a woman in China in 2025 came out in late November that year, short of Andrews’s mark. Each case taught the next drug regimen. Curtis has said the team changed medicines after what it saw in Andrews and Stewart. That is how a five-person series is supposed to work. It is not how a national waiting list of 95,492 is supposed to clear.

Andrews now lives with a human kidney that has worked since January 13, 2026. Wilma is out. Stewart also moved on to a human organ. Somewhere in Boston a woman is still making urine with a pig kidney that has lasted more than nine months. The list those three people came from is the same length it was before the Lancet paper, minus two deceased-donor kidneys that went to men who had already had their experimental pause.

Disclaimer: This article is news reporting on published clinical cases and company statements, and it is for information only. It is not medical advice, a transplant evaluation, or a recommendation to seek or decline any experimental organ, dialysis plan, or clinical trial. Anyone with kidney failure should talk with a transplant nephrologist and their own care team before making treatment decisions. Patient counts, graft survival times, waitlist totals, and trial dates reflect the papers, federal tables, and company updates cited here and can change as new cases are treated or as registries are revised.