Has Regenerative Medicine Come of Age?

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For the past few years the Signals blog site –  which offers an insiders’ perspectives on the world of regenerative medicine and stem cell research – has hosted what it calls a “Blog Carnival”. This is an event where bloggers from across the stem cell field are invited to submit a piece based on a common theme. This year’s theme is “Has Regenerative Medicine Come of Age?” Here’s my take on that question:

Many cultures have different traditions to mark when a child comes of age. A bar mitzvah is a Jewish custom marking a boy reaching his 13th birthday when he is considered accountable for his own actions. Among Latinos in the US a quinceañera is the name given to the coming-of-age celebration on a girl’s 15th birthday.

Regenerative Medicine (RM) doesn’t have anything quite so simple or obvious, and yet the signs are strong that if RM hasn’t quite come of age, it’s not far off.

For example, look at our experience at the California Institute for Regenerative Medicine (CIRM). When we were created by the voters of California in 2004 the world of stem cell research was still at a relatively immature phase. In fact, CIRM was created just six years after scientists first discovered a way to derive stem cells from human embryos and develop those cells in the laboratory. No surprise then that in the first few years of our existence we devoted a lot of funding to building world class research facilities and investing in basic research, to gain a deeper understanding of stem cells, what they could do and how we could use them to develop therapies.

Fast forward 14 years and we now have funded 49 projects in clinical trials – everything from stroke and cancer to spinal cord injury and HIV/AIDS – and our early funding also helped another 11 projects get into clinical trials. Clearly the field has advanced dramatically.

In addition the FDA last year approved the first two CAR-T therapies – Kymriah and Yescarta – another indication that progress is being made at many levels.

But there is still a lot of work to do. Many of the trials we are funding at the Stem Cell Agency are either Phase 1 or 2 trials. We have only a few Phase 3 trials on our books, a pattern reflected in the wider RM field. For some projects the results are very encouraging – Dr. Gary Steinberg’s work at Stanford treating people recovering from a stroke is tremendously promising. For others, the results are disappointing. We have cancelled some projects because it was clear they were not going to meet their goals. That is to be expected. These clinical trials are experiments that are testing, often for the first time ever in people, a whole new way of treating disease. Failure comes with the territory.

As the number of projects moving out of the lab and into clinical trials increases so too are the other signs of progress in RM. We recently held a workshop bringing together researchers and regulators from all over the world to explore the biggest problems in manufacturing, including how you go from making a small batch of stem cells for a few patients in an early phase clinical trial to mass producing them for thousands, if not millions of patients. We are also working with the National Institutes of Health and other stakeholders in discussing the idea of reimbursement, figuring out who pays for these therapies so they are available to the patients who need them.

And as the field advances so too do the issues we have to deal with. The discovery of the gene-editing tool CRISPR has opened up all sorts of possible new ways of developing treatments for deadly diseases. But it has also opened up a Pandora’s box of ethical issues that the field as a whole is working hard to respond to.

These are clear signs of a maturing field. Five years ago, we dreamed of having these kinds of conversations. Now they are a regular feature of any RM conference.

The simple fact that we can pose a question asking if RM has come of age is a sign all by itself that we are on the way.

Like little kids sitting in the back of a car, anxious to get to their destination, we are asking “Are we there yet?” And as every parent in the front seat of their car responds, “Not yet. But soon.”

How many stem cell trials will it take to get a cure?

When I think about how many clinical trials it will take before a stem cell therapy is available to patients, I’m reminded of the decades old Tootsie Pop commercial where a kid asks a series of talking animals, “How many licks does it take to get to the Tootsie Roll center of a Tootsie Pop?”

While Mr. Cow, Mr. Fox, and Mr. Turtle are all stumped, Mr. Owl tackles the question like a true scientist:

“A good question. Let’s find out. [Takes Tootsie pop and starts licking]. A One…A Two-hoo…A Three-hee. [Insert loud crunching sounds] A Three!”

The commercial ends with the narrator concluding that the world may never know how many licks it takes to get to the center (because Mr. Owl failed to complete his experiment…not a true scientist after all).

What do Tootsie Pops have to do with stem cell therapies?

I’m not saying that the Tootsie Pop question holds the same level of importance as the question of when scientists will develop a stem cell therapy that cures a disease, but I find it representative of the confusion and uncertainty that the general public has about when the “promise of stem cell research” will become a reality.

Let me explain…

Mr. Owl claims that it only takes three licks to get to the center of a Tootsie Pop, but three licks obviously aren’t enough to get through the hard candy exterior to the chewy tootsie center. According to the Tootsie “Scientific Endeavors” page, “at least three detailed scientific studies” determined that it takes between 144-411 licks to get to the center. My intuition is to go with the scientists, but depending on how the experiment was conducted or maybe the size of the tongue used, the final answer could vary.

Embryonic stem cells

Embryonic stem cells

For stem cell clinical trials, the situation is similar. The first clinical trial approved in the U.S. using human embryonic stem cells was in 2009. Since then, hundreds of clinical trials have been conducted globally using pluripotent – either embryonic or induced pluripotent stem cells (iPSCs) – or adult stem cells. But so far, none have made their way routinely to patients outside of a clinical trial setting in the U.S., (although a few stem cell-based products have been approved in other countries), and it’s unclear how many more trials it will take to get to this point.

Part of this murkiness is because we’re still in the early days of stem cell research: human embryonic stem cells were first isolated by James Thomson in 1998, and iPSCs weren’t discovered by Shinya Yamanaka until 2006. Scientists need more time to conduct preclinical research to understand how these stem cells can be best used to treat certain diseases and what stem cells will do when transplanted into patients.

Another other issue is that the U.S. Food and Drug Administration (FDA) has only approved one stem cell therapy – cord blood stem cell transplantation – for commercial use in 2011 and none since then. A big debate is currently ongoing about whether the regulatory landscape needs to change so that stem cell treatments that show promise in trials can get to patients who desperately need them.

Hopefully soon, the FDA will adopt a more efficient strategy for approving stem cell therapies that still keeps patient safety at the forefront. Otherwise it could take a lot longer for newer stem cell technologies like iPSCs to make their way to the clinic (although we’ve seen some encouraging preliminary results using iPSC-based therapy in clinical trials for blindness).

Trial, trial, trial again

So how many clinical trials will it take for a stem cell therapy to succeed sufficiently to gain approval and when will that happen?

Unfortunately, we don’t know the answers to these questions, but we do know that scientists need to continue to develop and test new stem cell treatments in human trials if we want to see any progress.

At CIRM, we are currently funding 16 clinical trials involving stem cell therapies for cancer, heart failure, diabetes, spinal cord injury and other diseases. But we need to fund more trials to increase the odds that some will make it through the gauntlet and prove both safe and effective at treating patients. Our goal now is to fund 50 clinical trials in the next five years. It’s an aggressive plan, but one we feel will hopefully take stem cell therapies from promise to reality.

We also know that CIRM is a soldier in a large army of funding agencies, universities, companies, and scientists around the world battling against time to develop stem cell therapies that could help patients in their lifetimes. And with this stem cell army, we believe we’re getting closer to the chewy center of the Tootsie pop, or in this case, an approved stem cell therapy for patients desperate for a cure.

This blog was written as part of the CCRM Signals iPSC anniversary blog carnival. Please click here to read what other bloggers have to say about the future of stem cells and regenerative medicine.