Chroma Medicine raises $135 million for its epigenetic editing therapies

The Boston startup is partly based on the work of three local scientists

An employee of Chroma Medicine at work in its Fenway labs. The company raised $135 million for its epigenetic editing therapies.Chroma Medicine

A Boston biotech startup is developing a new class of gene editing technologies that could control how our genetic code is read without changing the code itself. Chroma Medicine, whose labs are in the Fenway neighborhood, announced Wednesday that it raised $135 million towards that goal, bringing the company’s total funds to $260 million since it was founded in 2020.

Chroma’s approach, known as epigenetic editing, could have broad applications for treating both rare and common diseases. The technology is a twist on CRISPR gene editing that allows scientists to erase or write a chemical marker laid on top of DNA that controls whether it is turned on or off.

Chief executive Dr. Catherine Stehman-Breen wouldn’t say what diseases Chroma is focused on, although she noted that epigenetic editors could be useful for engineering cell therapies or tuning the expression of multiple genes involved in metabolic disease. Chief scientific officer Vic Myer added the technology might be able shut down the production of viruses that chronically infect human cells.

Epigenetic editing has excited some researchers who hope it will be a safer way of boosting the output of protective genes and blocking potentially harmful ones without making any alterations or incisions to DNA itself. But some scientists have cautioned that the complex molecular machines required to make epigenetic editing work in a human ― rather than cells in a petri dish or a mouse ― suggest that it could be many years before companies are able to prove that the technology is safe and effective in people.

The new financing came from more than a dozen investment firms and was led by GV — formerly Google Ventures, the investment arm of Alphabet. In February, investors at GV co-led a $193 million financing for Boston-based Aera Therapeutics, which is developing a new method for delivering gene editing therapies into hard-to-reach parts of the body. ARCH Venture Partners, a Chicago-based biotech venture capital firm, was an investor in both Aera and Chroma.

Chroma previously raised $125 million in 2021. The new financing comes at a time when many biotech startups are finding it difficult to raise money needed to keep the lights on, forcing some to downsize or even close altogether. Chroma has about 80 employees and Stehman-Breen said she plans to hire more, but wouldn’t say how many.

The firm is based on research from six scientific founders, including three CRISPR gene editing experts in Massachusetts: Keith Joung from Massachusetts General Hospital, David Liu from the Broad Institute of MIT and Harvard, and Jonathan Weissman from the Massachusetts Institute of Technology.

Chroma previously acquired the Italian biotech startup Epsilen Bio, founded by Angelo Lombardo and Luigi Naldini from the San Raffaele Telethon Institute for Gene Therapy, who became scientific founders of Chroma. Chroma’s other scientific founder is Luke Gilbert from the University of California, San Francisco.

Stehman-Breen wouldn’t say how long the new financing is expected to last, or even if the money would be enough to start testing the company’s first therapies in clinical trials. The goal, she said, “is to get as close to humans as possible.”