Editas Medicine Raises $120 Million to Advance Genome Editing

Cambridge, Massachusetts

Cambridge, Mass., August 10, 2015 – Editas Medicine, a leading genome editing
company, today announced that it has raised $120 million in a highly oversubscribed
Series B private financing. The financing assembles a broad syndicate of leading public
and private investors who underpin many of the most innovative biopharmaceutical and
technology companies. Editas is translating the promise of CRISPR/Cas9 technology into
a new class of transformative genomic medicines to treat a broad range of diseases by
enabling precise and corrective molecular modifications to treat disease at the genetic

“With this financing, we have a strong foundation from which we can broadly develop
our genome editing platform and advance multiple new therapies toward clinical trials,”
said Katrine Bosley, CEO, Editas Medicine. “We are grateful for such strong support
from so many high-quality investors who share our vision to translate this powerful
science into transformative medicines.”

The new investor syndicate was led by Boris Nikolic, M.D., managing director of bng0, a
U.S.-based investment company that was formed to invest exclusively in Editas Medicine
and includes a select group of large family offices with a global presence and long-term
investment horizon. Additional new investors include Deerfield Management, Viking
Global Investors, Fidelity Management & Research Company, funds and accounts
managed by T. Rowe Price Associates, Inc., Google Ventures, Jennison Associates on
behalf of certain clients, Khosla Ventures, EcoR1 Capital, Casdin Capital, Omega Funds,
Cowen Private Investments and Alexandria Venture Investments. The Company’s
founding investors, Flagship Ventures, Polaris Partners and Third Rock Ventures, as well
as Partners Innovation Fund, also participated in this financing. In conjunction with the
financing, Dr. Nikolic has joined the Editas Medicine board of directors.

“Editas Medicine has made great strides in the development of CRISPR/Cas9
technology,” said Dr. Nikolic. “The company is at the forefront of genome editing – one
of the most exciting and important frontiers in science. I look forward to joining the
board of directors and contributing to the team’s continued growth and success.”
Before creating bng0, Dr. Nikolic most recently served as chief advisor for science and
technology to Bill Gates at bgC3, the private office of Bill Gates, and at the Bill &
Melinda Gates Foundation, where he led select for-profit and not-for-profit investment
activities, including investments in various life sciences, information technology and
healthcare companies. Earlier, Dr. Nikolic completed postdoctoral training in
transplantation immunology at Harvard Medical School and served as an assistant
professor of medicine at Massachusetts General Hospital/Harvard Medical School.

About Genome Editing

Genome editing facilitates sequence-targeted modifications of DNA. The CRISPR
(Clustered, Regularly Interspaced Short Palindromic Repeats)/Cas9 (CRISPR-associated
protein 9) system, the newest genome editing approach, uses a protein-RNA complex
composed of an enzyme known as Cas9 bound to a guide RNA molecule designed to
recognize a particular DNA sequence. The RNA molecule guides the Cas9 complex to
the location in the genome that requires repair.
Recent advances in CRISPR-Cas9 genome editing have made it possible to modify
almost any gene in the human body with the ability to directly turn on, turn off or edit
disease-causing genes. This technology has the potential to address diseases that have
previously been intractable to traditional gene therapy, gene knock-down or other
genome modification techniques.

About Editas Medicine

Editas Medicine is a leading genome editing company and part of a transformational new
area of health care – genomic medicine. The company was founded by pioneers and
world leaders in genome editing bringing specific expertise in CRISPR/Cas9 and TALE
technologies. The Company’s mission is to translate its proprietary technology into novel
solutions to treat a broad range of genetically-driven diseases. For more information, visit