Michael Ehlers teases plan to build the next 'signature' genetic medicine company with $75M from Apple Tree Partners
When Michael Ehlers jumped ship at Biogen to become a venture partner and CSO at Apple Tree, he also got a new job as CEO of a gene therapy startup named Limelight Bio. The stealthy biotech is now ready to shed some — though not much — of its veils.
As ATP managing partner Seth Harrison tells it, the new venture grew out of a strong relationship with the co-founders, Jean Bennett and Phil Johnson. Bennett, who steered the early research on the landmark gene therapy eventually known as Luxturna alongside Spark Therapeutics CSO Kathy High, now leads Penn’s Center for Advanced Retinal and Ocular Therapies. Meanwhile, Johnson left his role at the Children’s Hospital of Philadelphia to become Limelight’s CSO.
“Initially we were focused on backing Jean and CAROT and some retinal dystrophy gene therapy projects using the standard AAV approaches,” he said, “but as we got to know the trove of technologies that were possible to access through Jean and Phil, some from Penn, some not, we’ve been very excited about the potential of creating a major gene therapy company.”
Limelight is pursuing gene therapy in its broadest sense. In addition to standard gene replacement delivered by adeno-associated virus, or AAV, the biotech will also explore non-viral approaches and what they call multi-exon gene correction.
The broad spectrum of targets and modalities Limelight is going after makes it unique, said Bennett, who’s also co-founded ophthalmology gene therapy company GenSight. Some of the ultra-rare diseases they want to treat would have been dismissed by most companies, she told Endpoints News.
The potential of this suite of technologies to move the needle on genetic medicine and scale it up across new diseases and geographies was also what drew Ehlers to the opportunity in the first place. ATP’s promise of substantial capital to deploy in the space probably didn’t hurt, either.
“The degree of efficacy you can get on these therapies is substantial, it’s not just incremental efficacy, you squint your eyes and you find a p-value,” he said.
With the well-known gene replacement tech, Limelight boasts of refined methods that allow them to slip in larger genes than previously possible and better control gene expression. As for gene correction, Ehlers is careful to distinguish what they’re doing from the “old classic typewriter” effect typically associated with gene editing.
“We are explicitly using the term ‘correction’ because we’re able to do much more than just one little point in the gene at a time,” he said. “We can do big portions at a time, at endogenous levels — and not requiring exogenous enzymes or co-factors” such as Cas9.
He also suggested their tech doesn’t come with risk of permanent genomic alteration, hinting at RNA or reversible DNA changes.
Just exactly how Limelight will accomplish those feats, or how many staffers are working on the tech platforms, or what manufacturing ops they have in place, Ehlers is not quite ready to disclose, saying multiple times to “stay tuned.”
He is, however, eager to preview that Limelight expects to be a clinical company in one to two years, ushering at least two programs in retinal diseases. That will be followed by programs in hematologic/metabolic, neurologic and hearing disorders — each on indications that they have identified with the quickest path to clinical and regulatory validation.
As Limelight takes the public stage on the same day Ehlers’ former colleagues at Biogen present one of biotech’s most anticipated datasets of the year at an Alzheimer’s conference, will he comment on a question that at least one analyst has wondered out loud: How in the world would he have left Biogen if he believed in aducanumab?
“My main focus is really how excited I am about Limelight and the promise of really building a signature gene therapy company,” Ehlers said.