Exsilio debuts with $82 million, making a ‘step’ forward for genetic medicine

Exsilio Therapeutics, a biotech startup led by a former Moderna executive, emerged from bankruptcy Tuesday with an approach it claims could solve some of the shortcomings of gene drugs.

The Boston-based company is debuting with $82 million from a group of investors that includes the venture arm of Novartis and gene-editing biotech CRISPR Therapeutics. It is led by interim CEO Tal Zaks, who was Moderna’s chief medical officer when the company successfully developed an RNA-based vaccine for COVID-19.

According to Zaks, Exsilio is taking a page from that effort. He aims to use mRNA, as well as other tools, to produce drugs that can effectively attach entire genes to cells and be administered more than once. The goal is to expand the reach of gene-based medicines in a scalable and more efficient way.

“We are leveraging what Moderna has demonstrated to work and expanding the scope of what can be achieved therapeutically with the flexibility of mRNA as a new class of medicine,” Zaks wrote in an email to BioPharma Dive.

Exsilio, which means “jump” in Latin, aims to do this by turning to so-called genetic elements, encoded in mRNA and delivered to the body via fat bubbles known as lipid nanoparticles. These genetic elements, Exsilio says, would then be programmed to insert the new DNA into the cells’ genomes at “safe harbor” sites that would not cause unwanted harm.

Exsilio believes this approach could allow it to treat a disease regardless of the specific genetic mutation that caused it. Such flexibility would be valuable, as some inherited conditions are associated with many different mutations. The effects of Exsilio’s drugs will be permanent, the company claims, because the inserted genes will be integrated into a cell’s genome, rather than being transiently expressed.

The company pitches its method as a way to circumvent the limitations of viral delivery systems commonly used for gene replacement therapy. For example, adeno-associated viruses are too small to contain several large genes and can trigger the body’s defenses, leading to side effects or compromising treatment. Some people already have immunity to certain AAVs, too, or develop it after receiving an AAV-based therapy, making retreatment more dangerous.

In contrast, Exsilio says its therapies will be able to be given more than once. “We should be able to dose patients regardless of their existing immunity, as well as repeatedly until the desired dose of the therapeutic gene is achieved,” Zaks wrote.

Exsilio targets genetic conditions, cancer and autoimmune diseases. The funding will help the company progress to the point of selecting its lead candidates, though it did not say when it expects to bring a prospect to human testing.

The story continues

Novartis Venture Fund and Delos Capital co-led the Series A round, which included other investors such as OrbiMed and a new life sciences fund of a JP Morgan division. The company was founded in 2022 and was founded by OrbiMed.

“We were impressed by Exsilio’s genomic medicine approach that enables the integration of large genes in a safe and repeatable manner,” Aaron Nelson, a managing director of Novartis’ venture fund, said in a statement.

Exsilio is one of many biotechs working to expand the field of gene medicines with the help of newer approaches. In recent years, well-funded companies like Prime Medicine, Tessera Therapeutics and Tome Biosciences have launched with similarly grand ambitions.

“It’s hard to compare very early technology — the proof will be in the drugs companies are able to develop for patients,” Zaks wrote.

This story was originally published on BioPharma Dive. To receive daily news and insights, subscribe to our free daily BioPharma Dive newsletter.