From Cell Stem Cell to Clinical Trials: The Biotech Journey of Two Papers

Abstract

How many of the authors who publish in Cell Stem Cell dream that their work will eventually wind up in the clinic? Probably quite a few. In the 10 years since its launch, Cell Stem Cell has featured many innovative discoveries, and several of them have gone on to become the seeds of burgeoning biotechnology companies with therapeutic aspirations. Two scientists who have seen that happen are Benjamin Reubinoff (Figure 1) and Derrick Rossi (Figure 2), both of whom led the clinical translation of technologies that made their public debut in Cell Stem Cell.Figure 2Derrick Rossi and the Moderna Preclinical mRNA Production FacilityShow full caption© 2017 Moderna Therapeutics. All rights reserved.View Large Image Figure ViewerDownload Hi-res image Download (PPT) © 2017 Moderna Therapeutics. All rights reserved. Moderna Therapeutics, the RNA-manufacturing startup that has grown into the most highly valued private biotechnology company ever, can trace its roots to Derrick Rossi’s study published in Cell Stem Cell in 2010 (http://www.cell.com/cell-stem-cell/fulltext/S1934-5909(10)00434-0). Although Moderna is currently focusing its efforts on anti-viral vaccines, its core technology—modified RNA—started as a more efficient method for inducing pluripotency and differentiating stem cells. The initial studies were geared toward basic research, but Moderna recognized and pursued a diverse array of potential clinical applications. On the other hand, the Israeli stem cell therapy company Cell Cure Neurosciences (Cell Cure) is currently tackling macular degeneration with a stem cell therapy that evolved from work that Benjamin Reubinoff and his partner, Eyal Banin, published in Cell Stem Cell in 2009 (http://www.cell.com/cell-stem-cell/fulltext/S1934-5909(09)00336-1). Cell Cure hopes that transplanting stem-cell-derived retinal cells into affected patients will help slow the process of this disease. Both of these companies moved from original research findings to initial clinical trials in about the same time frame, but they took very different routes to get there and learned different lessons along the way. Cell Cure founder and chief scientific officer Benjamin Reubinoff of Hadassah-Hebrew University Medical Center has worked toward using stem cells in medicine since the 1990s. “Being a physician scientist, conducting research that has a potential for clinical applications has always been my focus,” he says. After earning his M.D. in Israel, Reubinoff pursued a Ph.D. at Monash University in Australia, where he gained at-the-bench experience working in one of the first groups to derive stem cells from human embryos. Upon returning to Jerusalem, Reubinoff continued to work on stem cells, specifically motivated by the idea of developing stem cell lines that could be differentiated into clinically useful cells. However, he quickly discovered that developing clinical-grade lines would require many changes to the original protocols. Standards for manufacturing clinical biological agents are stricter than the standards for research-grade cell lines, requiring Reubinoff and colleagues to find alternatives to the animal-derived reagents that labs were using at the time. “People [did] not foresee this, but this was really a big hurdle,” Reubinoff says. However, after many “work-intensive adjustments,” they were able to derive three clinical-grade stem cell lines. The next step was then choosing a disease where stem cell-derived cells might make a difference. Choice of “indication”—medical speak for the problem that a medicine or therapeutic technique is meant to address—can make or break an emerging biotechnology. Picking a rare disease with a small market will likely discourage investors, while choosing a disease that already has well-established treatments may prompt investors to balk at spending money on an unproven alternative. Diseases that are poorly understood or have too many moving parts can lead to strings of failed experiments that exhaust funding. Reubinoff needed a widespread but hard-to-treat disease, where an infusion of new cells would likely make a functional difference in the clinic. He and his team considered Parkinson’s, diabetes, and multiple sclerosis as potential indications, but for all of those conditions, it was challenging to produce pure populations of functional differentiated cells in large enough quantities for stem cell therapy. Instead, in collaboration with Eyal Banin, Director of Hadassah’s Center for Retinal and Macular Degeneration, they became interested in age-related macular degeneration (AMD), which is the leading cause of blindness in people over 65. AMD is a disease of the eye’s retina, where the retinal pigment epithelial (RPE) cells that support retinal vision cells are damaged or die. The most common form of AMD—dry AMD—currently has no FDA-approved treatment. Reubinoff and Banin believed that if they could differentiate their stem cells into RPE cells, transplanting those healthy RPE cells into aging retinas might halt or slow the progression of AMD, and thus offer a clinical treatment for millions affected by this disease. After several years of research, they were able to differentiate human embryonic stem cells into RPE cells and transplant those RPE cells into a rat model of retinal degeneration, where they rescued retinal structure and function. That study, published in Cell Stem Cell in 2009, marked a turning point: the RPE cell project was transferred to the biotech company Cell Cure Neurosciences, then a subsidiary of Embryonic Stem Cell International Pte Ltd. Cell Cure Neurosciences had been founded in 2005 with the goal of developing cell transplantation therapies for neurodegenerative conditions, but RPE cell transplantation seemed to be a promising lead, and the company made a change in direction. Reubinoff and Banin continued to supervise the research there, but the next hurdle was generating funding for further studies. “While academic grants and philanthropic donations supported the proof-of-principle preclinical studies that we performed and [that] were published in 2009 in Cell Stem Cell, I think that extensive governmental and commercial investment is needed for translation to the clinic,” says Reubinoff. Luckily, the Israeli government saw stem cell therapy as an area where Israel might be able to distinguish itself scientifically and was actively pushing for more stem cell therapy research. Reubinoff says that both government and private funding were crucial for continuing the experiments, even though both sources of funding can be volatile. In 2010, Cell Cure’s ability to sustain itself financially was waning, but in a fortunate development, BioTime, Inc. bought out Cell Cure’s parent company and injected additional funding to keep the project going. Today, the RPE cell treatment—which Cell Cure has branded as “OpRegen”—is in phase I/IIa clinical trials to assess safety, led by Banin. In OpRegen, the RPE cells are suspended in liquid that can be injected into the subretinal space in the eye, causing less damage than surgically implanting a scaffold with the cells would. Reubinoff says that the initial findings for OpRegen are encouraging: so far there have been no major adverse reactions, and the cells seem to be able to engraft and persist in the subretinal space for at least 1 year. The next round of trials will assess whether the OpRegen cells preserve or improve retinal function, as well as continue to monitor their safety. Moderna Therapeutics, by contrast, is not a stem cell therapy company at all, even though the proof of concept for Moderna’s RNA modification technology came out of a stem cell lab at Boston Children’s Hospital. The origins of the company trace back to an entirely different pioneering stem cell technology. When the Nobel-Prize-winning induced pluripotent stem cell (iPSC) paper by Shinya Yamanaka and colleagues came out in 2007, stem cell researcher Derrick Rossi and his colleagues were floored by the advance but also curious about whether there might be safer or more efficient ways to induce pluripotent stem cells. They thought it might be possible to reprogram cells with messenger-RNAs encoding the reprogramming “Yamanaka factors,” but when cells’ anti-viral defenses detect foreign mRNA, most cells self-destruct. However, research from Katalin Karikó and Drew Weissman at the University of Pennsylvania suggested that RNAs with artificial base pairs might be able to side-step cells’ anti-viral responses, so Rossi’s team decided to try using artificial RNAs with modified base pairs to encode reprogramming factors. The initial results seemed almost too good to be true. The modified mRNA worked “literally on the first experiment,” Rossi recalls. A few months later, Rossi’s lab succeeded in using modified RNAs to make iPSCs and differentiate them into muscle cells. “In that one paper, we had made GFP, RFP, the four canonical reprogramming factors, LIN28, and MyoD,” Rossi says. “In one paper, we had made eight different modified RNAs encoding eight different proteins, but the possibilities are limitless. You can make any protein. You can basically just encode a new sequence.” Almost immediately, biological supply makers began approaching Rossi about licensing the technology for use in stem-cell-inducing kits. “What surprised me about that was that none of these people said, ‘Hey! We’d really like to use your technology for making proteins,’” says Rossi. “And that’s what the technology does! I mean, we used it to make reprogramming proteins, but you could use it to make any protein.” Eventually, Rossi decided that launching his own biotech company would let him explore the full range of possibilities. Rossi sought out a co-founder with extensive experience in building biotech companies around technology from basic research labs and teamed with MIT’s Bob Langer, who has founded over two dozen companies. Then the newly established Moderna began to court funding from angel investors and venture capitalists (VCs). Naturally, one of the first questions from most VCs was: what disease will these RNAs be used to treat? Rossi’s lab had managed to make mRNAs for several dozen different proteins within the span of 3 months, so he was very optimistic about the technology’s versatility. “I said, ‘Oh, maybe we can go after 25 or 50 indications.’ And all of these guys, these seasoned VCs, in the room looked at me like I was a total nutjob,” Rossi says. In the end, Moderna’s founders decided to focus on refining the RNA platform. “You develop your platform so that your platform is as great as it could possibly be,” says Rossi. “Then focus on the killer apps. The killer apps are your disease programs, which they’ve been doing now for the past 3–4 years and getting clinical programs going.” Now that Moderna has achieved billion-dollar “unicorn” start-up status twice over, the company does develop dozens of modified RNAs in parallel, just as Rossi initially suggested. Moderna is known for filing massive patents that are essentially bundles of modified RNAs for hundreds of proteins. But Rossi is the first to admit that the tale of the modified RNA and Moderna is a “crazy unicorn story” and therefore an atypical case. For scientists who are considering taking their research in a translational direction, he advises focusing their efforts on approaches that, if successful, would provide the greatest value to patients. Rossi spent 3 years on Moderna’s board of directors and 4 years on its scientific board before cutting ties to the company so he could focus on other ventures. Moderna was his first company, but he has since co-founded a stem cell transplantation start-up called Magenta Therapeutics and a CRISPR therapeutics company called Intellia. He is also currently working on three new biotech ventures that are as yet undisclosed. Rossi notes that as Moderna became more focused on clinical applications, their research moved away from his core areas of expertise. “It’s not uncommon for academic founders to have their time and place where they contribute value, and that’s often early in the phase of the company and less so in the later phases of the company,” says Rossi. “But there [are] also people who stay on and contribute.” Today, Moderna is making its first forays into human clinical trials with RNA vaccines against viruses such as Zika and the flu. Finding ways to safely deliver mRNA drugs will likely be the company’s next hurdle. So what does it take to get a technique from basic stem cell research into the clinic? First, understanding your technology’s promises and limitations is crucial, because it allows you to target areas where the technique can make a real difference. “You have to focus,” says Rossi. “Originally I thought about doing both stem cell biology and therapeutics. That’s unrealistic, and it’s something I didn’t know then… Moderna made the focus, and it focused on therapeutics because it’s a real market.” Willingness to court venture capital is also important, both Rossi and Reubinoff noted. There are challenges and challenging personalities in the VC space, but there are few substitutes for VC funding. When approaching VCs, the academic scientists’ job is to clearly and succinctly present the technology, its potential uses, and why it stands out from the crowd. Promising areas in biotech tend to yield multiple companies, which often end up competing with each other for funding. RNA therapeutics startups like RaNA Therapeutics and CureVac are already direct competitors to Moderna, and “there will be more,” according to Rossi. However, the presence of other therapies with similar mechanisms can also be a boon to biotech company founders. “The fact that embryonic stem cells are now approaching the clinic in a few projects… may make it easier to cross the Valley of Death and persuade potential investors that the valley is not so deep,” says Reubinoff. Basic science researchers looking to translate their findings into clinically useful therapies must familiarize themselves with the regulatory landscape. “Translation of hESCs from basic research to a clinical transplantation trial is a complex area that requires specific knowledge that I was not familiar with as a basic scientist,” says Reubinoff. “I feel that I have been fortunate to learn and overcome the great scientific, regulatory, and financial challenges of translating human embryonic stem cell basic research findings into a clinical trial.” Rossi echoes that sentiment, saying, “Without question, basic research and translational start-up[s] have… different mindset[s]. But this means that there is so much to learn—and indeed I learned a great deal from founding Moderna that has informed how I’ve thought in subsequent companies that I have and continue to be involved in founding.” As these stories both illustrate, the path from paper to product is often not straightforward, and can involve quite a lot of adaptation and a certain degree of luck along the way. But, the rewards are also clear, in terms of technological developments and, ultimately, positive impact on patients. “It’s very exciting to see work that we have published move forward and reach the point where it’s being used in clinical trials,” says Cell Stem Cell Editor-in-Chief Deborah Sweet. “I look forward to seeing many more of our papers get picked up for development and move beyond the bench and into the therapeutic arena.” Directed Differentiation of Human Embryonic Stem Cells into Functional Retinal Pigment Epithelium CellsIdelson et al.Cell Stem CellOctober 02, 2009In BriefDysfunction and loss of retinal pigment epithelium (RPE) leads to degeneration of photoreceptors in age-related macular degeneration and subtypes of retinitis pigmentosa. Human embryonic stem cells (hESCs) may serve as an unlimited source of RPE cells for transplantation in these blinding conditions. Here we show the directed differentiation of hESCs toward an RPE fate under defined culture conditions. We demonstrate that nicotinamide promotes the differentiation of hESCs to neural and subsequently to RPE fate. Full-Text PDF Open ArchiveHighly Efficient Reprogramming to Pluripotency and Directed Differentiation of Human Cells with Synthetic Modified mRNAWarren et al.Cell Stem CellSeptember 30, 2010In BriefClinical application of induced pluripotent stem cells (iPSCs) is limited by the low efficiency of iPSC derivation and the fact that most protocols modify the genome to effect cellular reprogramming. Moreover, safe and effective means of directing the fate of patient-specific iPSCs toward clinically useful cell types are lacking. Here we describe a simple, nonintegrating strategy for reprogramming cell fate based on administration of synthetic mRNA modified to overcome innate antiviral responses. Full-Text PDF Open Archive