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The next step in Weissman's research was to transplant the cancer cells into the paws of laboratory mice to see if the tumors would metastasize to other parts of the mouse's body. Without pre-treatment, for example, 10 out of 10 mice injected with bladder cancer cells developed tumors in other locations away from the injection site.
Only one of 10 mice given a CD47 inhibitor before being injected with bladder cancer cells, however, developing a cancerous lymph node, the other nine staying cancer-free. And even after cancerous colon and breast cancer tumors formed in other mice, giving the mice the CD47 inhibitor caused the tumors to shrink.
Weissman and colleagues are ready, after receiving a $20 million grant from the California Institute for Regenerative Medicine, to begin testing the new medication in humans. Phase I of testing, however, will only involve cancer patients who are not eligible for any other kind of treatment, typically volunteers with stage 4 cancers.
What Could Go Wrong with the New Cancer Drug?
It's far too early to label Dr. Weissman's new anti-cancer medication as a miracle drug. It's not really known whether the medication will work inside the human body in the same way it has worked inside the mouse body.
There is a possibility that the stress of treatment will result in normal cells producing more CD47 than normal, enabling them to evade detection by the immune system if the underlying process causing the cancer is not addressed. And even in the Stanford experiments, treating live mice with the CD47 inhibitor resulted in more immune system attacks on healthy tissue.
Still, Weissman's Research Potentially Points to the Holy Grail in the War on Cancer
Nonetheless, many experts believe that this line of research may lead to finding the ultimate drug for eliminating cancer. The primary drugs for treating most kinds of cancer have not changed in over 30 years. The odds of living for 5 years after diagnosis with cancer after the age of 65 is still only about 10%. Managing a patient's death, most cancer specialists will tell you, is no fun.
Even more maddeningly, drugs that seem to hold the promise of a cure for one kind of cancer tend not to be very useful for other kinds of cancer. Gleevec, for instance, is practically a miracle drug against chronic myelogenous leukemia, but it is of no use at all against acute lymphocytic leukemia. Avastin is effective against colon cancer, but holds no benefits for treating breast cancer.
Dr. Weissman and colleagues may have stumbled on the one medication that may treat most kinds of cancer. Only time and testing will tell. But if you are diagnosed with cancer in 2023 or 2033 instead of 2013, treatment may be as simple as getting a shot that enables your own immune system to complete your treatment.