One Drug to Shrink All Tumors - Page 1

Wow.

http://news.sciencemag.org/sciencenow/2012/03/one-drug-to-shrink-all-tumors.html?ref=wp

A single drug can shrink or cure human breast, ovary, colon, bladder, brain, liver, and prostate tumors that have been transplanted into mice, researchers have found. The treatment, an antibody that blocks a "do not eat" signal normally displayed on tumor cells, coaxes the immune system to destroy the cancer cells.

A decade ago, biologist Irving Weissman of the Stanford University School of Medicine in Palo Alto, California, discovered that leukemia cells produce higher levels of a protein called CD47 than do healthy cells. CD47, he and other scientists found, is also displayed on healthy blood cells; it's a marker that blocks the immune system from destroying them as they circulate. Cancers take advantage of this flag to trick the immune system into ignoring them. In the past few years, Weissman's lab showed that blocking CD47 with an antibody cured some cases of lymphomas and leukemias in mice by stimulating the immune system to recognize the cancer cells as invaders. Now, he and colleagues have shown that the CD47-blocking antibody may have a far wider impact than just blood cancers.

"What we've shown is that CD47 isn't just important on leukemias and lymphomas," says Weissman. "It's on every single human primary tumor that we tested." Moreover, Weissman's lab found that cancer cells always had higher levels of CD47 than did healthy cells. How much CD47 a tumor made could predict the survival odds of a patient.

To determine whether blocking CD47 was beneficial, the scientists exposed tumor cells to macrophages, a type of immune cell, and anti-CD47 molecules in petri dishes. Without the drug, the macrophages ignored the cancerous cells. But when the CD47 was present, the macrophages engulfed and destroyed cancer cells from all tumor types.

Next, the team transplanted human tumors into the feet of mice, where tumors can be easily monitored. When they treated the rodents with anti-CD47, the tumors shrank and did not spread to the rest of the body. In mice given human bladder cancer tumors, for example, 10 of 10 untreated mice had cancer that spread to their lymph nodes. Only one of 10 mice treated with anti-CD47 had a lymph node with signs of cancer. Moreover, the implanted tumor often got smaller after treatment -- colon cancers transplanted into the mice shrank to less than one-third of their original size, on average. And in five mice with breast cancer tumors, anti-CD47 eliminated all signs of the cancer cells, and the animals remained cancer-free 4 months after the treatment stopped.

"We showed that even after the tumor has taken hold, the antibody can either cure the tumor or slow its growth and prevent metastasis," says Weissman.

Although macrophages also attacked blood cells expressing CD47 when mice were given the antibody, the researchers found that the decrease in blood cells was short-lived; the animals turned up production of new blood cells to replace those they lost from the treatment, the team reports online today in the Proceedings of the National Academy of Sciences.

Cancer researcher Tyler Jacks of the Massachusetts Institute of Technology in Cambridge says that although the new study is promising, more research is needed to see whether the results hold true in humans. "The microenvironment of a real tumor is quite a bit more complicated than the microenvironment of a transplanted tumor," he notes, "and it's possible that a real tumor has additional immune suppressing effects."

Another important question, Jacks says, is how CD47 antibodies would complement existing treatments. "In what ways might they work together and in what ways might they be antagonistic?" Using anti-CD47 in addition to chemotherapy, for example, could be counterproductive if the stress from chemotherapy causes normal cells to produce more CD47 than usual.

Weissman's team has received a $20 million grant from the California Institute for Regenerative Medicine to move the findings from mouse studies to human safety tests. "We have enough data already," says Weissman, "that I can say I'm confident that this will move to phase I human trials."

Very exciting and encouraging research. My mom died from ovarian cancer, so this hits very close to home.

Sorry to hear that Starrchar. I lost my mom tragically but not to cancer. I did lose my dad to lung cancer so I hope they find a way to treat all these cancers easily and effectively without doing all the damage to the body that chemo and radiation can cause.

I am so sorry for your losses. No matter how our loved ones go it is always devastating.

Chemo is the best we've got for cancer patients right now. I must admit that the chemo served my mom well. She was 87 years old when she was diagnosed with late stage 3 ovarian cancer and she was given 3 years max to live (I never told her this until she was in her 6th year). She had multiple chemo treatments and lived for almost 7 years. What a gift... I lost her a year ago this month and still miss her terribly. She had such a sharp mind and was totally with it until she died. She was my mentor and hero. She will never be forgotten...

I do hope this drug turns out to be as miraculous as they hope. What a difference it would make in our world.

Thanks StarrChar.

My dad could not do chemo so pinpoint radiation was his only hope. But it was to late by the time he started getting it. Damn cigs. Took him way to early as far as I am concerned.

I to hope these new drugs and treatments pan out, they look very promising in early testing.