DEM BioPharma launches with $70m to take a bite out of cancer

The Cambridge startup is developing drugs that reveal malicious cells and allow the immune system to attack them.

David Donabedian is cofounder and chief executive of Cambridge startup DEM BioPharma.DEM BioPharma

DEM BioPharma launched Thursday with $70 million in seed and series A financing to develop cancer drugs based on science from the Whitehead Institute and Stanford University. The Cambridge startup is the latest company attempting to harness hungry immune cells called macrophages to attack and destroy cancer cells — by eating them.

Macrophages are part of the body’s front line of defense against disease. They engulf invading microbes such as bacteria and clear out dead or damaged cells. They can even target cancer ― if they can spot it. Many cancer cells don clever disguises to trick immune cells into thinking they are just a normal part of the body.

DEM Bio is one of several companies developing drugs that expose cancer cells to macrophages. “The idea is to uncloak the cancer cells so immune cells can recognize them,” said David Donabedian, its chief executive and cofounder.

One of the molecular masquerades that cancer cells use to hide is a protein called CD47. When a cancer cell places this protein on its surface, it tells macrophages to stay away. Scientists call it a “don’t eat me” signal. Antibody drugs that block CD47 allow macrophages to feast on, and thus kill, cancer cells. The still-experimental strategy has become increasingly popular in recent years.

In 2020, Gilead Sciences bought the smaller biotech firm Forty Seven for $4.9 billion to get its CD47 antibody. Last fall, Pfizer bought Trillium Therapeutics for about $2.3 billion for a similar experimental drug. I-Mab Biopharma has collaboration with AbbVie, and ALX Oncology has partnerships with Merck and Co. and Eli Lilly for their own CD47 drugs.

DEM Bio is searching for other “don’t eat me” signals that can be blocked with antibody therapies to unleash macrophages on cancer cells. Pheast Therapeutics, based in Palo Alto, California, launched with $76 million in April with a similar goal. That firm was founded by some of the same scientists that founded Forty Seven.

Donabedian said that what sets DEM Bio apart is its ability to methodically search for new “don’t eat me” signals. The company uses CRISPR gene editing to deactivate genes in cancer cells, and then places those cells in a dish with macrophages, he explained. If the macrophages start chomping on the cancer, the deactivated gene must be a “don’t eat me” signal. That gives the company a target to start making a cancer drug.

The idea is based on the work of Jonathan Weissman, a biologist at the Whitehead Institute, Dr. Kipp Weiskopf, a research fellow at the Whitehead and physician at Dana-Farber Cancer Institute, and Michael Bassik, a cancer biologist at Stanford University.

The company hopes that finding alternative targets for CD47 could lead to safer or more effective drugs. Since CD47 is found on blood cells, drugs that block it can spur macrophages to destroy blood cells, which can cause anemia, Donabedian said. The company isn’t disclosing what kind of cancer it will initially focus on, but he said it will likely take two or three years before it has a drug ready for testing in people.