Another patient has received a transplant with a genetically modified pig kidney. Tim Andrews, a 66-year-old who lives in Concord, N.H., has end-stage kidney disease and had been on dialysis for more than two years to compensate for his failing kidney function.

It was the fourth pig kidney transplant in the United States, and the first of three that will be done at Mass General as part of a new clinical trial sanctioned by the Food and Drug Administration. Two of the previous patients died shortly after the procedure, including one who was critically ill before the transplant.

Surgeons at Massachusetts General Hospital have successfully performed the fourth pig kidney transplant in the U.S.&nb

The surgery comes at a turning point in the quest to tell if animal-to-human transplants could help ease the shortage of donated human organs.

The FDA will allow two biotechnology companies to run clinical trials: United Therapeutics and eGenesis. United Therapeutics Corporation will start with six patients but could grow its trial to include up to 50 individuals, while eGenesis plans to begin with three patients.

A team at Massachusetts General Hospital led by Harvard Medical School physician-scientists has for the second time successfully transplanted a genetically edited pig kidney into a living person. The team performed the first surgery of its kind in the world in March 2024.

The recipient was Tim Andrews, a 66-year-old New Hampshire resident who had end-stage kidney disease and was on dialysis for more than two years.