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a tactic that cancer cells use to evade the immune system and survive. The signal emanates from a protein called CD47, and Weissman has founded a cancer company called Forty Seven to pursue drugs based on the underlying biology. (The company has just received a new California state grant to run a trial of a colon cancer drug, according to the California Stem Cell Report.)
Shizuru said the rights to exploit CD47 biology for transplant-related drugs are still in Stanford’s hands, but licensing them to Forty Seven “seems reasonable.” (She said she has no financial interest in the company.)
If efforts like those at Magenta, Stanford, and elsewhere prove successful, they might end up giving transplant doctors a more varied range of tools that can be tailored to different medical situations. Conditioning a patient by attacking CD45, for example, could provide a more complete kill of the bone marrow, perhaps necessary for cancer patients. Using naked antibodies should preserve some marrow cells and allow a patient to keep a functional immune system, said Shizuru, which could be a better approach for people with non-cancerous chronic blood diseases such as sickle cell or beta thalassemia.
New genetic medicines that use CRISPR-Cas9 and other techniques are likely to make an impact first in blood-borne disease. They will still require stem cell transplants. “The potential merging of success in this arena and what I do would be amazing,” said Matthew Porteus, also at Stanford, who recently published results of preclinical studies using CRISPR-Cas9 to fix the sickle cell mutation in hematopoeitic stem cells, adding to the growing body of academic work in the field.
Beyond cancer and other blood diseases, researchers have their eye on transplants to help people with autoimmune diseases, where the patient’s immune system goes awry and causes irreversible damage. Hundreds of multiple sclerosis patients whose disease had not responded well to other treatments have received transplants to reboot the immune system. (A review of those cases is here.) But generally, autoimmune diseases like MS aren’t considered perilous enough to risk transplants.
Whether new methods come from Magenta, Stanford, or other groups, it seems that stem cell transplants could play a much larger role in medicine in coming years. “We’ve been using the same agents for decades,” said Shizuru. “It’s time to change.”
Photo from the collection “Bone Marrow Donation” by Andrew Ratto via Creative Commons.