Pig to human kidney transplantation hits a new milestone

A kidney transplanted into a human patient from a genetically modified pig has broken records by lasting for around nine months, buying time until a human donor organ became available.

66-year-old Tim Andrews from New Hampshire was seriously ill with end-stage kidney disease caused by type 2 diabetes – and facing only a small chance (around 9%) of getting a kidney from a human donor in the next five years given current waiting lists – when he was transplanted with an EGEN-2784 pig kidney developed by US biotech eGenesis last year under an expanded access programme.

A case study published in The Lancet describes how the kidney lasted for 271 days, setting a new record and allowing him to become dialysis-free, before it started to fail and he received an organ from a dead human donor.

The surgery, carried out at Massachusetts General Hospital in Boston, marks the first time that a pig's kidney has been used as a temporary bridge to a human transplant, according to the study authors, and also comes just a couple of years after the world's first-ever transplant of a pig kidney into a human. That patient survived 52 days before death from cardiac causes unrelated to the transplant.

The milestones in xenotransplantation – cross-species transplants – rely on cutting-edge biotechnologies, including the use of CRISPR gene editing to remove harmful pig genes and add certain human genes to improve the organ's compatibility with recipients.

Since March 2024, five patients with kidney failure have received EGEN-2784 kidney transplants, with three achieving sustained kidney function for at least eight months without dialysis. Two of the five patients have now successfully transitioned to human donor kidneys, according to eGenesis.

"The organ shortage is the greatest crisis we have right now in transplantation," said case study lead author Leonardo Riella of the Centre for Transplantation Sciences at Mass General Brigham.

"We know that the best treatment option for patients with end-stage kidney disease who have developed renal failure is transplantation, but we simply don't have enough human organs to transplant in a timely manner," he added. In the US, around 100,000 people are waiting for a kidney, but only around 25,000 transplants occur each year.

"Our vision is that xenotransplantation could help address this gap, initially as a bridge to get patients off dialysis while they wait for a human donor kidney and, potentially, as we establish long-term safety and durability, as a destination therapy in its own right."

The FDA has cleared a phase 1/2/3 trial – called RESTORE – that will put EGEN-2784 through its paces in 33 patients with kidney failure aged between 50 and 70 years of age and on the waiting list. eGenesis expects to start that trial in the first quarter of next year.

Photo by Lucia Macedo on Unsplash