Talking about regeneration

What experts are telling me about the march of pluripotent stem cell therapies.

Yes, it takes years to translate brilliant science into therapies, and the routes to translation aren’t predictable. Case in point, the California Institute for Regenerative Medicine, launched via state referendum 15 years ago among the excitement about pluripotent embryonic stem cells. The Institute has sponsored 56 clinical trials. By a quick count, only five of these trials are looking at pluripotent stem cells, the remainder testing adult stem cells for regeneration or cancer treatments.

The waters are muddied by hundreds of for-profit “stem cell clinics” that offer treatments with little or no clinical evidence. “There is no scientific basis for what these people are doing,” one prominent researcher told me. “It’s very important to draw a distinction between the malpractice and quackery of these unsubstantiated stem cell clinics and the incredibly high-tech serious science that is using all of the new targeted approaches to improve patient outcomes for really terrible diseases.”

Therapies based on induced pluripotent stem cells (iPSCs) are entering early studies. The first iPSC clinical trial for Parkinson’s disease launched last year in Japan, for example. jCyte kicked off a successful first trial to treat a degenerative eye condition in 2017 and should post early results of a follow-up study soon. Studies for cardiac condition are likely to launch in 2020, one based on research shown successful in macaques. Also next year, Sigilon Therapeutics expects to kick off a study for hemophilia A, and Semma Therapeutics is planning trials for insulin-producing pancreatic beta cells for type 1 diabetes. “I’m happy to tell you that Semma has solved the production problem for beta cells,” co-founder Douglas Melton told me.

Labs are gearing up for off-the-shelf cell therapies, by engineering “universal donor cells” that dodge immune reaction and/or retraining T cells and other bodyguards of the immune system. This is a very long road with many complexities and safety concerns. But progress is being made, with one example this year from Melton and colleagues.

Other researchers seek to apply what we’re learning about cell plasticity to form  desired cells directly within the body. Kristen Johnson of Scripps Research’s Calibr institute, for instance, leads a trial of a small molecule designed to make healthy new knee cells. At an earlier stage, diabetes researchers aim to develop insulin-producing cells by altering pancreatic alpha cells or a recently found population of pancreatic progenitor cells. Startups OxStem and Sana Biotechnology have wildly ambitious programs in this space.

We’ll see what actually translates but the scientists I talk with believe that stem cell research will change medicine dramatically and it won’t take 15 more  years.

Images courtesy Harvard Stem Cell Institute. On left, mouse induced muscle progenitor cells at various stages of differentiation, from Konrad Hochedlinger’s lab. Top right, human green kidney cells and red blood vessels, from work led by Jennifer Lewis and Ryuji Morizane. Bottom right, from the Melton lab, two clusters of human insulin-producing cells (pink), the cluster on the right demonstrating enrichment of these cells.

 

Capsule cures get beta

We’ve learned how to churn out zillions of insulin-producing cells and maybe even guard them from the immune system for a year or two.

The commercial “stem cell clinics” that have popped up across the U.S. like mosquitoes after rain, offering treatments with little clinic evidence, typically begin with the patient’s own cells. But the stem-cell-based therapies that will soon fundamentally change regenerative medicine will come off the shelf. Case in point, the insulin-producing treatments for type 1 diabetes that I’ve just covered in The Scientist, which are headed for the clinic in the next year or two. Scientists are mastering ways to make reasonably functional beta cells in high volume. ViaCyte is readying a new version of its capsule that doesn’t require immunosuppression and expects to resume clinical trials soon. Semma Therapeutics and Sigilon Therapeutics are reporting progress in pre-clinical studies. Fingers crossed here, but definite progress.

Images courtesy Sigilon Therapeutics.

Crossing the Ts in diabetes

Advances in cancer immunotherapy may help autoimmune therapies defend themselves.

allogeneic label

Is human immunology basically too crazy complex for the human mind? Evidence to date suggests yes, at least for my mind.

In almost every story I write about cancer immunology or autoimmune disease, I learn about previously unknown (to me) functions within the three-ring circus of immune cells. Or I find out about yet more types of these cells, like double-negative T cells, which can defend against graft disease and maybe type 1 diabetes. Who knew?

Well, yeah, thousands of immunologists.

All of us who follow cancer research, though, do know a (simplified) version of one genuine breakthrough in immunology, checkpoint blockade inhibitors, which garnered Nobel Prizes last October.

These drugs take on one of deepest questions in cancer biology: why the immune system doesn’t snuff out cancer cells, which by definition are genetically abnormal, often wildly abnormal.

Checkpoint blockades can hold off the T cells on patrol for just such outsiders. It turns out that a protein on the surface of tumor cells called PD-L1 can grab onto a surface protein on the T cell called PD-1 and so disarm the T cell. (Nothing to look at here, officer! Ignore my multiple heads and antitank guns!)

Other headlines in cancer immunotherapy come from chimeric antigen receptor T (CAR-T) cell drugs, treating patients with certain blood cancers in which B cells go bad. The two such drugs with FDA approval work by taking T cells from the patients, reengineering the T cells to attack those cancerous B cells, and reinserting the T cells.

This method is often effective when nothing else works, but is always worryingly slow and extremely costly.

So there’s plenty of work in labs, and a few clinics, to take a logical but intimidating next step: Engineering off-the shelf T cells to do the job, hiding them from each patient’s immune system with tricks learned from checkpoint blockade research and similar  immunology findings.

Still with me?

Okay, if those cell-shielding techniques eventually work, can a similar attack be made in autoimmune diseases such as type 1 diabetes?

In type 1 diabetes, effective ways to stop the autoimmune attacks from trigger-happy T cells exist only in lab mice. And that’s a problem not just in slowing or stopping disease progression but in trying to treat it. The most promising current approach is to encapsulate insulin-producing beta cells. This has been pursued for many decades, with many barriers. Perhaps the highest (if least surprising) barrier is that the capsules always get clogged up.

The latest capsule approaches, starting with beta cells made by reprogramming cells, try sophisticated material-science strategies to blunt this attack and may do much better.

But as long as we’re already playing genetic games with those engineered beta cells, why not also try  immune-evading tricks similar to those being studied in CAR-T experiments?

That’s the basic idea behind efforts by Altheascience, a Viacyte/CRISPR Therapeutics collaboration, and others. Which just maybe will produce capsules that, replaced every year or so as necessary, are working cures for type 1 diabetes. Which we would all fully understand.

Celling out cancer

As immunotherapies start to change clinical practice, we hope for more.

CI_cover_crop

For a blockbuster drug, pembrolizumab comes with a strange history, nicely told here by David Shaywitz.

Pembro is a “checkpoint inhibitor”, a biologic designed to take the brakes off T cells so that they can wipe out tumors. Back in 2014, it was the first drug that targets the PD-1 protein on the surface of T cells to get FDA approval. Also now known as Keytruda, pembro has received FDA green lights for many kinds of cancers. It accounts for billions of dollars each year and is in more than 500 clinical studies.

But it was born in a small Israeli biotech trying to develop treatments for autoimmune diseases by putting brakes on T cells (yes, the reverse of checkpoint inhibition).  The small biotech that created pembro and realized it was a promising cancer drug candidate was soon bought by a larger pharma firm, which was then acquired by Merck & Co. As Shaywitz notes, the giant pharma shut down development not once but twice, before successful trials of other checkpoint inhibitors changed its mind.

Today pembro comes as a colorless liquid in a small IV pouch, looking very much like saline solution. It lists at around $50 a milligram, one case in point for the extremely real concern about how any country can pay for such drugs as they start to become standard of care.

You don’t think about costs, however, if you’re in a clinic as I was earlier this month, watching a friend with metastatic melanoma joke with the nurse hooking up his IV. You just hope the treatment works.

It’s been a pleasure to edit this month’s Nature Outlook on cancer immunotherapy. Many thanks to the outstanding authors, editors and designers who put it together! And to Elin Svensson, who created the great cover art above.

Blossoms in biomedicine

The remarkable global push for cancer immunotherapies.
El_Talayón.byJose Ignacio Martinez Navarro
Editing a Nature special report on cancer immunotherapies, I’m struck most by the sheer scale of the development effort. Something like 3,000 clinical trials are underway, 800 of them combining treatments. The FDA has approved five checkpoint inhibitors, designed to unleash T cells against tumors. The agency seems close to approving the first CAR-T cell treatment, in which a patient’s T cells are removed, reengineered to attack cancer cells, regrown in volume and returned to the patient. Old dogs of immunotherapies are learning new tricks. Some newer approaches are getting much attention—notably personalized neoantigen vaccines, in which individual tumors are sequenced to give clues on how to best target their unique sets of immune-system-alarming antigens. Some clinical trials fail, some do surprisingly well.  The competition is more than intense and trials are not always carefully planned or analyzed. But the landscape is changing.

Moving the needles

Updates on progress in research against type 1 diabetes.

BetaBionics

JDRF New England’s annual research briefing offers a quick summary of research for type 1 diabetes. Here are four snapshots from last night’s talks by JDRF’s Julia Greenstein and University of Colorado’s Peter Gottlieb:

  1. The march continues toward an “artificial pancreas” that automatically provides just the right amounts of insulin around the clock. The first of four NIH-sponsored pivotal clinical trials kicked off in February. Many of us are most intrigued by the Beta Bionics combo device, designed to deliver both insulin (which lowers blood glucose levels) and glucagon (which raises them). This device is a few years behind some of its competitors, but we like it for the same reason we would prefer a self-driving car with brakes.
  1. JDRF has awarded more than 50 grants for research on encapsulating insulin-producing beta cells derived from stem cells, to initiatives such as the Boston Autologous Islet Replacement Therapy Program. News from the much-watched Viacyte clinical trial, however, is not so good. The Viacyte capsule prevents against some immune response but generates a foreign-body reaction. Next–generation encapsulation technologies may do better on immune response but must still grapple with another fiendishly tricky issue—admitting suitably high levels of oxygen to the beta cells. (The pancreas is even hungrier for oxygen than the brain, Greenstein noted.)
  1. For decades, immunologists in both cancer and autoimmune diseases like type 1 diabetes made important discoveries that didn’t translate into better treatments. That unhappy situation has changed bigtime with cancer immunology, and diabetes researchers are now adopting two general strategies in cancer treatment. One strategy is to recognize that the disease may work quite differently in different people—for example, in trials of drugs designed to delay or prevent progression of the disease, often one group responds much better than another. So “personalized medicine”, tailored to specific groups of patients, may recast the field in type 1 just as it has done with many forms of cancer. The second strategy aims to confront the complexity of the disease by combining treatments, as the University of Miami’s Jay Skyler has proposed.
  1. No clear winners have ever emerged from the dozens of trials of drugs designed to delay or prevent type 1 diabetes onset. One contender that’s still standing is oral insulin acting as a vaccine. Drug companies have chased the elusive goal of an insulin pill for a century (with a few recent signs of progress) but such pills typically get ripped apart in your gut without lowering your blood glucose levels. However, the resulting fragments of insulin may generate an anti-immune protective response in the pancreas. Early clinical tests of this vaccine concept (such as this one reported in 2015) have shown promise for some patients. The latest clinical results, including early findings from a phase II trial with higher doses, will be announced on June 12th at the American Diabetes Association annual scientific sessions. We’ll be watching!

Beta living through stem cells

Insulin-producing cells will be tested first in patients lacking a pancreas.

insulin

Diabetes is way complex. “But it’s a simple disease conceptually—your body doesn’t produce enough insulin,” notes Joslin Diabetes Center researcher Gordon Weir.

In type 1 diabetes, an autoimmune attack wipes out insulin-producing beta cells, which are found in clusters of pancreatic cells called islets. In type 2 diabetes, the beta cells are still there but not hauling all the freight. That disease can be treated with many other types of drugs, along with lifestyle changes. But over time, beta cells wear out. In fact, more people with type 2 take insulin than people with type 1.

And there’s no way to make insulin injections pleasant or easily controllable or as good as insulin production by beta cells.

Thus the huge interest in a long-term research project spearheaded by Harvard’s Doug Melton to create working beta cells by manipulating stem cells. An update on the ambitious project from Melton, Weir and other partners drew a crowd at Harvard on Monday.

Making insulin-producing cells good enough for clinical trials “turns out to be rather difficult; it took more than a decade,” Melton said. “We haven’t made it really perfect, but it’s at the goal line.”

Technology from Melton’s lab has been licensed exclusively to the startup Semma Therapeutics, which is joining with Joslin, Brigham & Women’s Hospital and Dana-Farber Cancer Institute to move toward clinical trials. Traveling under the ungainly title of the Boston Autologous Islet Replacement Therapy Program (BAIRT), the collaboration launched in June.

The first BAIRT studies, starting at least three years from now, will not be among people with type 1 diabetes. Instead, they will recruit people who have had their pancreases removed, usually because of uncontrollable pain after the organs are chronically inflamed by years of heavy drinking.

This approach bypasses the biggest problem in cell treatments for type 1 diabetes: the body renews its autoimmune attack and wipes out the newly introduced cells. “We decided to solve one problem at a time,” Melton explained.

Patients who have prostatectomies often now are given islet cells salvaged from their own pancreas, which helps to improve their diabetes control, but those cells may themselves be damaged or in short supply, said Brigham surgeon Sayeed Malek. Transplants of brand-new beta cells, made from the patients’ own blood, should help.

These reengineered cells will be injected in the arm, where they will be easy to monitor  and to remove if necessary, said Semma CEO Robert Millman. Decades of experience transplanting cells from cadavers has shown that “you can put beta cells just about anywhere,” Weir added.

Against autoimmunity. If all goes well, the project will continue into trials for type 1 diabetes with non-personalized beta cells, where the autoimmune attack will be blunted via encapsulating the cells. Seema is spending about half its budget on encapsulation technologies, Millman said.

Encapsulation is the near-term solution to fend off the autoimmune attack. “The long-term solution is to use the power of biology to understand why the immune system has made this mistake,” Melton remarked.

He briefly mentioned two promising research thrusts. One effort is to learn from the rapid advances in knowledge about how cancer cells dodge the immune system.

Another, led by Chad Cowan of Massachusetts General Hospital, aims to create a “universal donor pluripotent stem cell.” Missing all the billboard signs that alert immune enforcers, these cells could play a role like that of O-positive cells in blood transfusions.

Asked about his own take on the causes of type 1, Melton mentioned one theory that the autoimmune attack may be triggered by gut cells that naturally produce insulin or similar substances under certain conditions.

Slow and steady. Bringing beta cell therapies to the clinic will be a marathon march with not only many scientific steps but many regulatory steps. Millman emphasized, however, that “the FDA is working with us very early on the regulatory path.”

Among potential safety risks, all stem cell therapies must be carefully vetted to avoid the growth of teratomas—tumors with a jumbled mix of cells, usually benign. These cellular junk piles would be relatively easy to remove, but much better to avoid altogether, Millman said.

Another concern is that the cells will secrete insulin even when it’s not needed, dropping the recipient’s blood sugar levels to dangerously low levels.

There also is much cause for worry that the cells won’t last long, a major problem in transplants of cadaver beta cells. However, built-from-scratch cells function “for more than a year in mice, which bodes well for people,” Weir commented. And Millman pointed out that the cells resemble juvenile cells, which may help them withstand the high stresses of transplantation better than worn-out adult beta cells do. “We hope these almost pristine cells going into the patients will last a lot longer,” he said.

None of this will come cheap. Asked about pricing for cell therapies, way down the road when and if they hit the market, Millman was understandably wary. Initial costs for these treatments will be very high, accompanied by very close regulatory scrutiny. Semma has raised about $50 million, but “we need philanthropy and we need institutions to support this,” he said.

Melton suggested, though, that successful cell-based therapies will make complete  economic sense, given the soaring numbers of people with diabetes and the huge costs of diabetes care. Each year the world spends about $30 billion on insulin alone. “Diabetes is not an orphan disease,” he said. “The cost will come down very quickly.”