SAN ANTONIO -

A new cancer drug is showing promise among patients suffering from lung cancer, melanoma, and renal cell cancer.

The drug, called MK3475, was part of a research trial involving 17 patients at the South Texas Accelerated Research Therapeutics Center, known around the world as the START Center.

Dr. Lon Smith, a medical oncologist at the START Center, is calling the drug an amazing new development in treating certain kinds of cancers.

“This is really a big change in the way we approach the treatment of this disease,” Dr. Smith said. “Once the body learns how to attack the tumor, it remembers how to do it. So as a result, we get a long, durable, response that we have really not seen with any other agents.”

MK3475 is not yet approved by the Federal Drug Administration, but was granted “breakthrough status,” putting it on the fast-track for approval.

Dr. Smith said in human trials, MK3475 caused less side effects than traditional cancer treatment because the drug attacks the tumor directly. The drug, which is administered by vein every three weeks, takes about 30 minutes per treatment.

“I'm thrilled with it. I never dreamed that things would turn out this way,” said Edwin Bowles, 68, a patient who participated in the trials. “I had my hopes, but this far exceeded my expectations.”

Bowles, who was first diagnosed with lung cancer in 2004, underwent surgery, followed by chemotherapy until 2007. Earlier this year, he was told his cancer had returned, and there was no available treatment because the cancer was so advanced.

Dr. Smith said he has seen remarkable progress since Bowles began taking the drug.

While MK3475 has shown promise in melanoma, lung, and renal cell cancer cases, Dr. Smith said patients with colon and pancreatic cancer showed no response after taking the drug.

Other research centers around the world are now testing MK3475 while doctors wait for final FDA approval.