New Hope for Organ Transplantation: Life Without Anti-Rejection Drugs
Rob Waddell dreaded getting a kidney transplant. He suffers from a genetic condition called polycystic kidney disease that causes the uncontrolled growth of cysts that gradually choke off kidney function. The inherited defect has haunted his family for generations, killing his great grandmother, grandmother, and numerous cousins, aunts and uncles.
But he saw how difficult it was for his mother and sister, who also suffer from this condition, to live with the side effects of the drugs they needed to take to prevent organ rejection, which can cause diabetes, high blood pressure and cancer, and even kidney failure because of their toxicity. Many of his relatives followed the same course, says Waddell: "They were all on dialysis, then a transplant and ended up usually dying from cancers caused by the medications."
When the Louisville native and father of four hit 40, his kidneys barely functioned and the only alternative was either a transplant or the slow death of dialysis. But in 2009, when Waddell heard about an experimental procedure that could eliminate the need for taking antirejection drugs, he jumped at the chance to be their first patient. Devised by scientists at the University of Louisville and Northwestern University, the innovative approach entails mixing stem cells from the live kidney donor with that of the recipient to create a hybrid immune system, known as a chimera, that would trick the immune system and prevent it from attacking the implanted kidney.
The procedure itself was done at Northwestern Memorial Hospital in Chicago, using a live kidney donated by a neighbor of Waddell's, who camped out in Chicago during his recovery. Prior to surgery, Waddell underwent a conditioning treatment that consisted of low dose radiation and chemotherapy to weaken his own immune system and make room for the infusion of stem cells.
"The low intensity chemo and radiation conditioning regimen create just enough space for the donor stem cells to gain a foothold in the bone marrow and the donor's immune system takes over," says Dr. Joseph Levanthal, the transplant surgeon who performed the operation and director of kidney and pancreas transplantation at Northwestern University Feinberg School of Medicine. "That way the recipient develops an immune system that doesn't see the donor organ as foreign."
"As a surgeon, I saw what my patients had to go through—taking 25 pills a day, dying at an early age from heart disease, or having a 35% chance of dying every year on dialysis."
A week later, Waddell had the kidney transplant. The following day, he was infused with a complex cellular cocktail that included blood-forming stem cells derived from his donor's bone marrow mixed what are called tolerance inducing facilitator cells (FCs); these cells help the foreign stem cells get established in the recipient's bone marrow.
Over the course of the following year, he was slowly weaned off of antirejection medications—a precaution in case the procedure didn't work—and remarkably, hasn't needed them since. "I felt better than I had in decades because my kidneys [had been] degrading," recalls Waddell, now 54 and a CPA for a global beverage company. And what's even better is that this new approach offers hope for one of his sons who has also inherited the disorder.
Kidney transplants are the most frequent organ transplants in the world and more than 23,000 of these procedures were done in the United States in 2019, according to the United Network for Organ Sharing. Of this, about 7,000 operations are done annually using live organ donors; the remainder use organs from people who are deceased. Right now, this revolutionary new approach—as well as a similar strategy formulated by Stanford University scientists--is in the final phase of clinical trials. Ultimately, this research may pave the way towards realizing the holy grail of organ transplantation: preventing organ rejection by creating a tolerant state in which the recipient's immune system is compatible with the donor, which would eliminate the need for a lifetime of medications.
"As a surgeon, I saw what my patients had to go through—taking 25 pills a day, dying at an early age from heart disease, or having a 35% chance of dying every year on dialysis," says Dr. Suzanne Ildstad, a transplant surgeon and director of the Institute for Cellular Therapeutics at the University of Louisville, whose discovery of facilitator cells were the basis for this therapeutic platform. Ildstad, who has spent more than two decades searching for a better way, says, "This is something I have worked for my entire life."
The Louisville group uses a combination of chemo and radiation to replace the recipient's immune and blood forming cells with that of the donor. In contrast, the Stanford protocol involves harvesting the donor's blood stem cells and T-cells, which are the foot soldiers of the immune system that fight off infections and would normally orchestrate the rejection of the transplanted organ. Their transplant recipients undergo a milder form of "conditioning" that only radiates discrete parts of the body and selectively targets the recipient's T-cells, creating room for both sets of T-cells, a strategy these researchers believe has a better safety profile and less of a chance of rejection.
"We try to achieve immune tolerance by a true chimerism," says Dr. Samuel Strober, a professor of medicine for immunology and rheumatology at Stanford University and a leader of this research team. "The recipients immune system cells are maintained but mixed in the blood with that of the donor."
Studies suggest both approaches work. In a 2018 clinical trial conducted by Talaris Therapeutics, a Louisville-based biotech founded by Ildstad, 26 of 37 (70%) of the live donor kidney transplant recipients no longer need immunosuppressants. Last fall, Talaris began the final phase of clinical tests that will eventually encompass more than 120 such patients.
The Stanford group's cell-based immunotherapy, which is called MDR-101 and is sponsored by the South San Francisco biotech, Medeor Therapeutics, has had similar results in patients who received organs from live donors who were either well matched, such as one from siblings, meaning they were immunologically identical, or partially matched; Talaris uses unrelated donors where there is only a partial match.
In their 2020 clinical trial of 51 patients, 29 were fully matched and 22 were a partial match; 22 of the fully matched recipients didn't need antirejection drugs and ten of the partial matches were able to stop taking some of these medications without rejection. "With our fully matched, roughly 80% have been completely off drugs up to 14 years later," says Strober, "and reducing the number of drugs from three to one [in the partial matches] means you have far fewer side effects. The goal is to get them off of all drugs."
But these protocols are limited to a small number of patients—living donor kidney recipients. As a consequence, both teams are experimenting with ways to broaden their approach so they can use cadaver organs from deceased donors, with human tests planned in the coming year. Here's how that would work: after the other organs are removed from a deceased donor, stem cells are harvested from the donor's vertebrae in the spinal column and then frozen for storage.
"We do the transplant and give the patient a chance to recover and maintain them on drugs," says Ildstad. "Then we do the tolerance conditioning at a later stage."
If this strategy is successful, it would be a genuine game changer, and open the door to using these protocols for transplanting other cadaver organs, including the heart, lungs and liver. While the overall procedure is complex and costly, in the long run it's less expensive than repeated transplant surgeries, the cost of medications and hospitalizations for complications caused by the drugs, or thrice weekly dialysis treatments, says Ildstad.
And she adds, you can't put a price tag on the vast improvement in quality of life.
Science's dream of creating perfect custom organs on demand as soon as a patient needs one is still a long way off. But tiny versions are already serving as useful research tools and stepping stones toward full-fledged replacements.
Although organoids cannot yet replace kidneys, they are invaluable tools for research.
The Lowdown
Australian researchers have grown hundreds of mini human kidneys in the past few years. Known as organoids, they function much like their full-grown counterparts, minus a few features due to a lack of blood supply.
Cultivated in a petri dish, these kidneys are still a shadow of their human counterparts. They grow no larger than one-sixth of an inch in diameter; fully developed organs are up to five inches in length. They contain no more than a few dozen nephrons, the kidney's individual blood-filtering unit, whereas a fully-grown kidney has about 1 million nephrons. And the dish variety live for just a few weeks.
An organoid kidney created by the Murdoch Children's Institute in Melbourne, Australia.
Photo Credit: Shahnaz Khan.
But Melissa Little, head of the kidney research laboratory at the Murdoch Children's Institute in Melbourne, says these organoids are invaluable tools for research. Although renal failure is rare in children, more than half of those who suffer from such a disorder inherited it.
The mini kidneys enable scientists to better understand the progression of such disorders because they can be grown with a patient's specific genetic condition.
Mature stem cells can be extracted from a patient's blood sample and then reprogrammed to become like embryonic cells, able to turn into any type of cell in the body. It's akin to walking back the clock so that the cells regain unlimited potential for development. (The Japanese scientist who pioneered this technique was awarded the Nobel Prize in 2012.) These "induced pluripotent stem cells" can then be chemically coaxed to grow into mini kidneys that have the patient's genetic disorder.
"The (genetic) defects are quite clear in the organoids, and they can be monitored in the dish," Little says. To date, her research team has created organoids from 20 different stem cell lines.
Medication regimens can also be tested on the organoids, allowing specific tailoring for each patient. For now, such testing remains restricted to mice, but Little says it eventually will be done on human organoids so that the results can more accurately reflect how a given patient will respond to particular drugs.
Next Steps
Although these organoids cannot yet replace kidneys, Little says they may plug a huge gap in renal care by assisting in developing new treatments for chronic conditions. Currently, most patients with a serious kidney disorder see their options narrow to dialysis or organ transplantation. The former not only requires multiple sessions a week, but takes a huge toll on patient health.
Ten percent of older patients on dialysis die every year in the U.S. Aside from the physical trauma of organ transplantation, finding a suitable donor outside of a family member can be difficult.
"This is just another great example of the potential of pluripotent stem cells."
Meanwhile, the ongoing creation of organoids is supplying Little and her colleagues with enough information to create larger and more functional organs in the future. According to Little, researchers in the Netherlands, for example, have found that implanting organoids in mice leads to the creation of vascular growth, a potential pathway toward creating bigger and better kidneys.
And while Little acknowledges that creating a fully-formed custom organ is the ultimate goal, the mini organs are an important bridge step.
"This is just another great example of the potential of pluripotent stem cells, and I am just passionate to see it do some good."
Phil Gutis never had a stellar memory, but when he reached his early 50s, it became a problem he could no longer ignore. He had trouble calculating how much to tip after a meal, finding things he had just put on his desk, and understanding simple driving directions.
From 1998-2017, industry sources reported 146 failed attempts at developing Alzheimer's drugs.
So three years ago, at age 54, he answered an ad for a drug trial seeking people experiencing memory issues. He scored so low in the memory testing he was told something was wrong. M.R.I.s and PET scans confirmed that he had early-onset Alzheimer's disease.
Gutis, who is a former New York Times reporter and American Civil Liberties Union spokesman, felt fortunate to get into an advanced clinical trial of a new treatment for Alzheimer's disease. The drug, called aducanumab, had shown promising results in earlier studies.
Four years of data had found that the drug effectively reduced the burden of protein fragments called beta-amyloids, which destroy connections between nerve cells. Amyloid plaques are found in the brains of patients with Alzheimer's disease and are associated with impairments in thinking and memory.
Gutis eagerly participated in the clinical trial and received 35 monthly infusions. "For the first 20 infusions, I did not know whether I was receiving the drug or the placebo," he says. "During the last 15 months, I received aducanumab. But it really didn't matter if I was receiving the drug or the placebo because on March 21, the trial was stopped because [the drug company] Biogen found that the treatments were ineffective."
The news was devastating to the trial participants, but also to the Alzheimer's research community. Earlier this year, another pharmaceutical company, Roche, announced it was discontinuing two of its Alzheimer's clinical trials. From 1998-2017, industry sources reported 146 failed attempts at developing Alzheimer's drugs. There are five prescription drugs approved to treat its symptoms, but a cure remains elusive. The latest failures have left researchers scratching their heads about how to approach attacking the disease.
The failure of aducanumab was also another setback for the estimated 5.8 million people who have Alzheimer's in the United States. Of these, around 5.6 million are older than 65 and 200,000 suffer from the younger-onset form, including Gutis.
Gutis is understandably distraught about the cancellation of the trial. "I really had hopes it would work. So did all the patients."
While drug companies have failed so far, another group is stepping up to expedite the development of a cure: venture philanthropists.
For now, he is exercising every day to keep his blood flowing, which is supposed to delay the progression of the disease, and trying to eat a low-fat diet. "But I know that none of it will make a difference. Alzheimer's is a progressive disease. There are no treatments to delay it, let alone cure it."
But while drug companies have failed so far, another group is stepping up to expedite the development of a cure: venture philanthropists. These are successful titans of industry and dedicated foundations who are donating large sums of money to fill a much-needed void – funding research to look for new biomarkers.
Biomarkers are neurochemical indicators that can be used to detect the presence of a disease and objectively measure its progression. There are currently no validated biomarkers for Alzheimer's, but researchers are actively studying promising candidates. The hope is that they will find a reliable way to identify the disease even before the symptoms of mental decline show up, so that treatments can be directed at a very early stage.
Howard Fillit, Founding Executive Director and Chief Science Officer of the Alzheimer's Drug Discovery Foundation, says, "We need novel biomarkers to diagnose Alzheimer's disease and related dementias. But pharmaceutical companies don't put money into biomarkers research."
One of the venture philanthropists who has recently stepped up to the task is Bill Gates. In January 2018, he announced his father had Alzheimer's disease in an interview on the Today Show with Maria Shriver, whose father Sargent Shriver, died of Alzheimer's disease in 2011. Gates told Ms. Shriver that he had invested $100 million into Alzheimer's research, with $50 million of his donation going to Dementia Discovery Fund, which looks for new cures and treatments.
That August, Gates joined other investors in a new fund called Diagnostics Accelerator. The project aims to supports researchers looking to speed up new ideas for earlier and better diagnosis of the disease.
Gates and other donors committed more than $35 million to help launch it, and this April, Jeff and Mackenzie Bezos joined the coalition, bringing the current program funding to nearly $50 million.
"It makes sense that a challenge this significant would draw the attention of some of the world's leading thinkers."
None of these funders stand to make a profit on their donation, unlike traditional research investments by drug companies. The standard alternatives to such funding have upsides -- and downsides.
As Bill Gates wrote on his blog, "Investments from governments or charitable organizations are fantastic at generating new ideas and cutting-edge research -- but they're not always great at creating usable products, since no one stands to make a profit at the end of the day.
"Venture capital, on the other end of the spectrum, is more likely to develop a test that will reach patients, but its financial model favors projects that will earn big returns for investors. Venture philanthropy splits the difference. It incentivizes a bold, risk-taking approach to research with an end goal of a real product for real patients. If any of the projects backed by Diagnostics Accelerator succeed, our share of the financial windfall goes right back into the fund."
Gutis said he is thankful for any attention given to finding a cure for Alzheimer's.
"Most doctors and scientists will tell you that we're still in the dark ages when it comes to fully understanding how the brain works, let alone figuring out the cause or treatment for Alzheimer's.
"It makes sense that a challenge this significant would draw the attention of some of the world's leading thinkers. I only hope they can be more successful with their entrepreneurial approach to finding a cure than the drug companies have been with their more traditional paths."