In a first-of-its-kind operation, a 71-year-old man with a liver tumor had the malignant lobe of the organ removed and replaced with a pig liver genetically engineered to resist rejection, his surgeons in China reported. Following the 17 May operation, he was in good health this week with no signs of infection or rejection, and the liver was producing healthy quantities of bile, says Sun Beicheng of the First Affiliated Hospital of Anhui Medical University, who led the operation. A team at Yunnan Agricultural University developed the genetically modified pig. Another team in China previously reported transplanting such a liver into a patient who had been declared brain-dead. The latest procedure adds to a growing list of transplants of genetically modified pig organs, including kidneys and hearts. But a setback came last week when surgeons at NYU Langone Health had to remove an engineered pig kidney from a woman 47 days after the transplant surgery because it stopped working.