Skin cancer therapy being studied here offers hope Posted Thursday, May 26, 2005 by arjuna
May 26, 2005, 12:42AM


By TODD ACKERMAN
Copyright 2005 Houston Chronicle

Advanced skin cancer patient Jesse Newman was getting his final affairs in order last year when he began a Houston trial of an experimental new treatment.
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Newman had never heard of the approach — injecting an agent that triggers the immune system — but he figured it was worth a try. After all, his melanoma had withstood surgery and chemotherapy and spread to his lungs in tumors too numerous to count.

Seven months later, Newman is back to his old self, working in his shop, building things, playing golf. The therapy has killed 90 percent of the tumors in his lungs and is shrinking the rest. Doctors expect them to be gone soon.

"I'm a miracle melanoma patient," said Newman, 66, an Alabama resident who estimates he's traveled to Houston for treatment some 40 times since his diagnosis in 2002. "One day, I was preparing for the worst. Now, I'm living a normal life, enjoying every day."

Newman is one of a number of patients showing remarkable benefits from CP-675, one of the most promising therapies in development for advanced melanoma — as deadly as brain, lung and pancreatic cancers. Because it is particularly resistant to chemotherapy and radiation, current treatment options are extremely limited.

In midtrial results presented at a cancer conference last week, University of Texas M.D. Anderson Cancer Center researchers reported a 43 percent response rate from CP-675, a human antibody that works by a process known as immunotherapy. The treatment enlists the immune system to attack malignant tumor cells responsible for the disease.

Thirty patients with advanced melanoma got the injection. The cancers of five went into remission and eight more either shrank at least 50 percent or stopped growing.

The response rates for two FDA-approved therapies for metastatic melanoma — cancer that has spread to other organs — are significantly less. For one, DTIC, the rate is 6 percent. For the other, Interleukin-2, it's 10 percent to 15 percent.

Improvement cited
The M.D. Anderson trial also represented an improvement over the cancer center's previous trial with the injection, presented at the same cancer conference in 2004. Of the 39 patients in that trial, tumors disappeared in three, shrank in a fourth and stopped growing in five other patients.

That study involved single injections. The new study involves multiple injections.

"These new results are very promising for patients' metastatic melanoma, a population with a great need for new treatments," said Dr. Luis Camacho, an investigator in the study and an M.D. Anderson professor of melanoma medical oncology. "There are really no good agents to treat melanoma once it's spread."

Camacho estimated it will probably be two years before the drug's maker, Pfizer, can go to the FDA for approval of CP-675.

The antibody targets the receptor that works as "the brakes" of the immune system. Like a vaccine, it seems to continue working long after patients receive the injections. It may work well in melanoma, said Camacho, because previous research has shown that once activated, the immune system can recognize the cancer.

Cancer vaccines are another kind of immunotherapy, though they too harness the immune system to fight the disease, not prevent it. But they have been largely unsuccessful in melanoma.

Because the CP-675 antibody triggers the immune system to attack cells that "look" similar to the body's own, researchers worried that it might produce autoimmune disorders such as rheumatoid arthritis. But the only side effects observed — rashes, diarrhea and hypothyroidism — were easily resolved.

Newman said he had no side effects.

Melanoma is the cancer with the nation's fastest growing incident rate. Curable if caught early but deadly thereafter, it afflicts some 58,000 Americans a year, killing 10,000. Texas is one of four states with the highest incident rate.

Researchers are expected to start enrolling patients soon for a study comparing the antibody to DTIC. If successful, it likely would be the last study necessary for FDA approval.