CD47 is a kind of protein that is found on the surface of many cells in the body. It tells circulating immune cells called macrophages not to eat these cells. The body uses the CD47 protein to protect cells that should be protected and to help dispose of cells that are aged or diseased. For instance, red blood cells start off with a lot of CD47 on their cell surface when young but slowly lose CD47 as they age. At some point, the amount of CD47 on the surface of an aging red blood cells is not enough to stave off the macrophages, and those older cells are devoured and destroyed, making way for new red blood cells. In this way, the supply of fresh blood cells is constantly replenished.
Unfortunately, some cells that should be destroyed are not. Researchers at Stanford have discovered that nearly every kind of cancer cell has a large amount of CD47 on the cell surface. This protein signal protects the cancer against attack by the body’s immune system. Stanford investigators have discovered if that they block the CD47 “don’t-eat-me” signal through the use of anti-CD47 antibodies, macrophages will consume and destroy cancer cells. Deadly human cancers have been diminished or eliminated in animal models through the use of anti-CD47 antibody.
Clinical Trials in humans
After the successful outcomes of the experiments testing the use of anti-CD47 antibodies against human cancers transplanted into mice, plans were immediately begun to start clinical trials in humans. Unfortunately, the process of preparing for human clinical trials is long. The initial experiments were done in animals and the animal versions of anti-CD47 antibody cannot be used in humans. So researchers first have to create a “humanized” antibody to CD47, then the production of antibody must be scaled up in a sterile facility of the kind that is used to create other pharmaceutical products. Finally, clinical trials must be designed so that the data they generate will produce a valid scientific result, and the trials must be approved by regulatory officials.
All of this takes time.
For the last year, many people have been working to make clinical trials possible. We are now hopeful that the first human clinical trials of anti-CD47 antibody will take place at Stanford in mid-2014, if all goes well. Clinical trials may also be done in the United Kingdom.
(1/14/14) Update on the anti-CD47 cancer therapy clinical trials
Researchers and staff at Stanford are continuing to work hard preparing the groundwork for the clinical trials of our anti-CD47 antibody as a cancer therapy. We are anticipating the start of clinical trials sometime in the first half of this year, though unforeseen delays may yet slow that progress. As we get closer to the start of the clinical trials, we will be posting information about eligibility for the trials and how to apply.
There has been a huge amount of interest in these trials from patients and their families and friends. However, we feel compelled to emphasize that, as is typical of FDA phase I clinical trials, the first tests of this therapy will be very small safety trials involving only a very few patients. Unfortunately, this means only a tiny fraction of those interested will be admitted to the first phase I clinical trials. Accordingly, we are urging patients to continue exploring existing treatments and other clinical trials.