Early testing of an experimental human monoclonal antibody showed a striking benefit in patients with advanced melanoma, say researchers at The University of Texas M. D. Anderson Cancer Center, who presented their findings at the annual meeting of the American Society of Clinical Oncology.
Of 39 patients given a single injection of CP-675,206 (known as CP-675), tumors disappeared in three patients, shrunk in a fourth patient, and cancer stopped growing in five other patients. These responses have remained since their initial treatment, which ranged from 13 to 28 months ago.
Most of the patients in the trial had advanced melanoma, which has a median survival of less than a year, says the study’s principal investigator, Luis Camacho, M.D., MPH, assistant professor in the Department of Melanoma Medical Oncology.
“We were very pleasantly surprised to find such objective antitumor responses in a Phase I clinical trial, which is designed to find the ideal dose and to look for side effects,” says Camacho. “These results are very early, but they are encouraging to us because there are no good agents available to treat melanoma once it has spread.”
The researchers gradually increased the amount of the initially tested dose by 1,500 fold, evaluating seven different dose levels, before they found higher doses that both produced an effect and had tolerable side effects. Most of the patients who did not respond to the drug were those treated with the lower doses, the investigators say.
The study was conducted at M. D. Anderson Cancer Center and at the University of California, Los Angeles. A collaborating researcher is Jesus Gomez Navarro, M.D., clinical director of the monoclonal antibody program at Pfizer, Inc., which developed the antibody and is sponsoring the clinical trial.