Laronde CEO Diego Miralles, MD, who is also CEO-Partner with Flagship Pioneering

No sooner did the messenger RNA (mRNA) COVID-19 vaccines of Pfizer/BioNTech and Moderna reach the first patients almost a year ago than Moderna’s first investor and a vice president at Pfizer, among others, spoke about the unlimited or endless possibilities of RNA therapeutics.

A four-year-old startup is putting that adage to the test.

Laronde recently completed $440 million in Series B financing led by Flagship Pioneering, which launched the company in 2017 and brought it out of stealth mode in May of this year, committing $50 million to the company.

Laronde is French for “the round,” which explains its approach to engineering a new class of RNA that is circular rather than linear. In circular RNAs, the free 3′ and 5′ ends found in linear RNA forms are joined together to form a closed loop that appears to render them stable and long-lasting—likely because the lack of free ends makes them impervious to exonuclease digestion.

Naturally occurring closed-loop RNAs cannot translate their sequences into proteins, as they are noncoding. However, Laronde’s Endless RNATM (eRNA) is a versatile synthetic RNA platform designed to instruct cells to express a desired therapeutic protein inside the body. Because eRNA has no free ends, it is not recognized by the immune system and is stable, enabling a longer duration of protein expression than linear RNA.

How long?

“We’re talking about weeks to months,” Laronde CEO Diego Miralles, MD, told GEN Edge. “We’ve seen expression in animals following a single dose. We’ve seen expression at therapeutic levels of some proteins for four months, so we’re talking about a long time.” That duration, Miralles said, allows for longer-lasting treatments as well as repeat redosing.

By engineering RNA into eRNA, Laronde aims to surmount one challenge to mRNA drugs and vaccines: While many have proven safe, effective, and highly manufacturable, as COVID-19 has shown, the RNA message being expressed has been found to be ephemeral.

“Say you have hemophilia and you need to replace a coagulation factor for the rest of your life. That [mRNA] platform is not so suitable because messages don’t last that long, and the expression of the protein doesn’t last.”

Hence the need for longer lasting eRNA.

“We’re building, as I always say, on the shoulders of giants. Messenger RNA companies did an amazing job over the past ten years validating translatable RNA. eRNA has additional benefits, additional features that make that that platform, apply to a lot more human diseases,” Miralles said. “The potential it has is immense.”

Unlocking modalities

That potential, Laronde says, includes the ability to treat disorders in numerous therapeutic areas, including cancer, cardiology and respiratory, dermatology, gastroenterology, genetic diseases, hematology, immunology and inflammation, metabolic diseases, musculoskeletal, neurology (including CNS), ophthalmology, and women’s health.

“We are not trying to build just one therapeutic area,” Miralles said. “We’re trying to unlock modalities. What does that mean? We don’t necessarily want to do programs one, two and three because they’re the ones that are going to be three blockbusters. We want to have programs one, two and three that unlock the platform in the sense that it shows some of the things that the platform can do.”

In addition to being persistent, eRNA is also programmable. Each closed loop of eRNA contains a “cassette” that codes for a desired therapeutic protein and can be digitally designed via computer. When inserted into the eRNA, the cassette directs the body to make different peptides, enzymes, antigens, antibodies, channels, and receptors, both inside and outside of the cell.

“By changing the sequence of the amino acids we want the cell to make at the nucleotide level—we put in a different set of codons for the open reading frame after the internal ribosome entry site—we can essentially make the eRNA produce, inside or outside the cell, a very different protein,” Miralles said.

In time, Laronde envisions that some of its eRNA-based therapies may be vaccines, others antibodies and still others, cell therapies.

Avak Kahvejian, PhD, a General Partner at Flagship Pioneering who co-founded Laronde

“The technology at the core is all the same; it’s endless RNA. And by programming a different set of information in the open reading frame, we can do all of these very disparate, very different modalities and therapeutic areas. That’s the beauty of eRNA!” said Avak Kahvejian, PhD, a General Partner at Flagship Pioneering who co-founded Laronde, served as its founding CEO, and now sits on its board.

“If you look at Laronde as a factory or as a foundry, you don’t have an antibody plant and a cell therapy plant and a vaccine plant. You have an eRNA plant that we’re designing in such a way that it can handle multiple programs, in parallel, with the same chemistry, albeit with very different modalities emerging inside the body,” Kahvejian added. “We’re just providing the instructions for the body to manufacture its own medicine inside. Those instructions are chemically always identical. Information-wise they’re very, very different.”

Kahvejian led the Flagship team that began developing eRNA in 2017, when he and colleagues started exploring the therapeutic applicability of lncRNA, naturally abundant in circular form within mammalian cells, after noticing a growing number of studies that reported discoveries of circular RNAs in humans and animals.

“We were intrigued by the fact that the genome was producing all of these different RNA formats, but very little was known about what they’re doing. There’s obviously small nucleolar RNAs and small activating RNAs and all these different formats of lncRNA. And nobody really understood what they do, what their potential could be,” Kahvejian recalled.

Circular Pursuit

Laronde is among several biotech companies pursuing development and commercialization of therapies based on circular RNA.

In February, two-year-old Orna Therapeutics emerged from stealth with $100 million in financing—including an $80 million Series A round—toward developing a new class of fully engineered circular RNAs it calls “oRNAs.” oRNAs are engineered as linear RNAs that undergo autocatalytic circularization designed for higher efficiency, followed by proprietary purification steps. The company uses proprietary IRES technology to maximize protein output and adapts lipid nanoparticle (LNP) technologies to create oRNAs that it says can safely reach sites in the body where they are needed.

Orna has attracted several big-name strategic investors that include Astellas Venture Management; Kite, a Gilead Company; Bristol Myers Squibb; and Novartis Institutes for Biomedical Research.

A circular RNA startup established last year, Chimerna Therapeutics, is working to develop treatments for autosomal-dominant polycystic kidney disease (ADPKD), Alzheimer’s and Parkinson’s diseases through its Tornado technology. Tornado uses DNA to direct cells to synthesize an RNA of interest, directed to enzymes normally found in the cell that causes that RNA to be converted from linear to circular RNA, as the front and back end of the RNA are “ligated” to each other. The resulting circles are stable and can accumulate to high levels in cells. The DNA can be delivered directly to tissues using lipid nanoparticles or packaged in adeno-associated viral particles.

At Laronde, Kahvejian and his Flagship Pioneering colleagues gravitated toward a circular form of lncRNA, given his background in mRNA translation, having studied with Nahum Sonenberg, PhD, whose research interests include identifying and characterizing the various translation factors involved in translation initiation.

“During my PhD work we had realized that mRNA actually circularizes itself transiently through protein RNA and protein-protein interactions, and that that helps it remain stable. It helps it be more translatable. And when that’s broken, then the RNA is removed and its translation is reduced. The format that we saw with the [lnc] circular RNA was an echo of that format, of that closed RNA loop,” Kahvejian said. “So, I got excited about the prospect of those being more stable and the prospect of those being perpetually translating or really good at translating.”

On those two hypotheses, Kahvejian said, he and colleagues were right on the first and somewhat wrong on the second: “We were right that these things are really more stable. We found them in cells that don’t make any new RNA months after the RNA was created, telling us that indeed they’re very different. Every other format of RNA is super unstable.”

Translation Challenge

But Kahvejian and colleagues also found that the lncRNAs were naturally either not translatable, or their translation was scant and weak in the absence of the free 5’ end needed in canonical processes to engage the ribosome to start reading mRNA.

Unlike mRNA, which initiates translation by recruiting ribosomes through interaction with proteins bound to the mRNA’s 5’ region, natural circular lncRNA does not readily interact with ribosomes.

“We decided to take matters into our own hands and invent a way to make them translatable,” he recalled.

Kahvejian and colleagues started to incorporate internal ribosome entry sites into the body of the message, creating a place for the ribosome to engage, and initiate the translation process. The group has been granted two U.S. patents (No. 10,953,033, issued March 23, and No. 11,058,706, issued July 13) related to pharmaceutical compositions and preparations of circular polyribonucleotides and uses thereof. Both patents have been assigned to Flagship Pioneering, where Kahvejian leads a team that invents and launches new therapeutic platforms, having been a partner since 2011.

Miralles took the helm of Laronde when he joined Flagship Pioneering as CEO-Partner in January. He previously served as CEO of Vividion Therapeutics and President of Adaptive Biotechnologies’ Adaptive Therapeutics division, as well as Global Head of Johnson & Johnson Innovation, where he led Janssen’s Research and Early Development Unit and established the company’s J&J Innovation Centers and Janssen/JLABS network in San Diego.

“Once in a Lifetime”

In joining Flagship, Miralles moved cross-country to the Boston/Cambridge, MA, region.

“Over the years, I had many people call me to come to Boston when I was in La Jolla. It was hard to leave, but Laronde is a really special company with a special platform that can really have a huge impact,” recalled Miralles, whose research interests have focused on the pathogenesis and treatment of HIV infection and the development of effective antiretroviral therapy. “I’m an HIV physician. I’ve always been focused on impact. I saw what great medicines did saving tens of millions of people around the world. eRNA is an incredible platform to build the medicines of the future for the world. That’s a once-in-a-lifetime opportunity.

Joining Flagship Pioneering in Laronde’s latest financing are funds and accounts advised by T. Rowe Price Associates, Invus, Canada Pension Plan Investment Board, Fidelity Management & Research Company, funds and accounts managed by BlackRock, and Federated Hermes Kaufmann Funds.

In addition to developing its eRNA platform, proceeds from the financing will also enable Laronde to expand its staff, which has grown to about 65 people: “We’re on track to be more than 100 by the end of the year,” Miralles said—halfway to the more than 200 people that the company said in May it expected to hire over the next two years.

Miralles says his staff are enjoying the opportunity to further develop the eRNA platform. “It’s in another level in terms of predictability and reproducibility, and that’s the beauty of what we do. It really is a game changer in terms of how we think about biopharmaceuticals.”