Why a recent pig kidney transplant is a major advance

By Lisa Jarvis

Last month, 53-year-old Towana Looney, of Gadsden, Alabama, became the third patient to receive a kidney from a genetically engineered pig. This advance in the field of xenotransplantation, or animal-to-human transplants, is a big one — and hopefully will not just be life-changing for Looney but can teach the field so much about how to bring these organs to more people.

Looney had few options open to her. She had donated a kidney to her mother in 1999, but years later suffered from a dangerous form of high blood pressure during pregnancy that ultimately led to kidney failure. Yet that experience and related blood transfusions also left her with a slew of antibodies that made it nearly impossible to find a suitable kidney donor. She’s been stuck with dialysis for eight long years.

Until this month. It’s only been three weeks since her transplant, but her pig kidney appears to be working beautifully. Doctors have navigated one episode where her immune system disagreed with the body’s new occupant, but she’s been up and moving around.

She might be just one patient, but by volunteering to receive an experimental organ, Looney is bringing the field of xenotransplantation much closer to its logical next step: clinical studies. Looney received the engineered pig kidney under a Food and Drug Administration program that allows compassionate use of experimental treatments. Moving the field forward will require the kind of gold standard data that proves these organs are safe for widespread use.

During a press conference this week, Looney gingerly walked to the dais to deliver a succinct message about her first weeks of post-transplant life: “I’m overjoyed.” She told reporters she was “full of energy,” with an appetite that has come roaring back after years where dialysis dampened her interest in food. She’s also remembering what it’s like to do basic things — like use the bathroom. “Gotta get used to that!” she laughed. But she’s also looking forward to what freedom from kidney disease might look like, noting Disney World was on her travel wish list.

Each pig organ transplant is an experiment, and Looney’s is a critical one. Whereas the two previous pig kidney transplants went to people who without it were facing the last days or weeks of their lives, she had been getting by on dialysis — albeit for far longer than most patients endure it.

And she also was beginning to develop the kind of health issues that would limit her life, says Robert Montgomery, director of the NYU Langone Transplant Institute, where the surgery was performed. “That’s really the time where she has the best chance of benefiting [from a transplant].” And if the pig kidney fails, she’s also in good enough health to recover and return to dialysis, he says.

That makes her exactly the kind of patient that ideally these organs ultimately will serve — those who have a slim chance of getting an organ, either because a match is unlikely, or they simply aren’t sick enough to be at the top of the list. Every year, demand far outstrips the supply of organs. According to the Organ Procurement and Transplant Network, more than 49,000 people were added to the waitlist for a kidney this year, while just over 27,000 received one.

Montgomery is familiar with the stress of waiting. He has a genetic condition that causes the heart muscle to break down over time. That genetic flaw killed his father and brother, and caused multiple near-death episodes where the surgeon’s heart stopped. And yet he still wasn’t sick enough to be near the top of the list. It took several years before he finally received a new heart in 2018.

“Living through that, it’s so clear to me that people don’t really understand the number of people who die every year where they don’t have the possibility of receiving a transplant,” he says.

The overwhelming need makes every piece of data collected from Looney’s experience crucial. Every test — and she is undergoing many — is an opportunity to understand how to better design and use xenotransplants.

Several different approaches are being taken to edit the genome of pigs to create organs for humans, and scientists want to know which genetic modifications are necessary, which are superfluous, and whether other edits might be needed. (Pigs are used because their organs are the right size for humans, they’re easily bred, and anyone who enjoys a Christmas ham shouldn’t have an ethical quandary with the practice.)

And researchers also need to know how best to use pig organs. With human-to-human transplants, doctors have decades of experience in recognising and treating organ rejection. Now, they need to figure out those same signs of trouble — as well as the right combination of drugs to stop the reaction from happening — with xenotransplants.

Previous transplants of pig organs to humans are providing researchers with important clues about how the immune system responds to a pig organ. Because Looney has far fewer health complications, and, if all goes well (still a big if), could live with the pig kidney for years, her experience could significantly expand on that knowledge.

It also is a prelude to xenotransplantation’s next big leap. Next year, United Therapeutics plans to ask the Food and Drug Administration to begin the first clinical trials of their pig organs. Although no one is giving away much about the shape of those studies, Montgomery notes that patients like Looney seem like the right fit for this next phase.

The field still has a lot to prove. But if each of these transplants is an experiment, it is also a promise: that one day, people like Looney won’t be left to languish on donor lists. In the meantime, I’m hoping Looney’s new kidney can carry her to Disney World.