CHARLOTTESVILLE, Va., – Results of an analysis published in today’s issue of The Lancet show that the investigational drug pegvisomant normalized concentrations of the hormone IGF-I in 97 percent of patients with acromegaly during 12 months of treatment in two open-label studies. IGF-I is a measure of the activity of the disease and of its debilitating effects.
Pegvisomant is the first in a new class of compounds called growth hormone receptor antagonists and is designed to block the effects of excessive growth hormone production by a tumor of the pituitary gland.
Acromegaly is a serious, life-shortening disease triggered by overproduction of growth hormone, most often caused by a pituitary tumor. This excess of growth hormone leads to overproduction of a second hormone, insulin-like growth factor-I (IGF-I).
“Pegvisomant lowered serum IGF-I levels to normal in more than 90 percent of patients during one year of treatment, according to our analysis,” said Dr. Michael O. Thorner, Henry B. Mulholland professor of internal medicine and professor of neurosurgery, University of Virginia Health System and one of the lead investigators in the international study. “We find these results encouraging since there has been no significant advance in the medical management of acromegaly in the past decade.”
The retrospective analysis of two open-label, dose titration studies was conducted by an international team of leading endocrinologists in the United States and Europe. The investigators examined the long-term efficacy of pegvisomant in the treatment of 152 patients with active acromegaly, for an average of 425 days.
Of the 90 patients who were treated for 12 months or longer with once-daily injections of pegvisomant, 87 patients (97 percent) achieved a normal serum IGF-I concentration. Pegvisomant was generally well tolerated in the study. Two patients experienced progressive growth of their pituitary tumors, and two other patients had elevations of aminotransferase (ALT) and aspartate transaminase (AST) requiring withdrawal from treatment.
“Pegvisomant has a novel mechanism of action,” Thorner said. “It blocks the action of growth hormone at the tissue level rather than relying on inhibition of growth hormone secretion from the tumor.”
Patients with acromegaly often suffer from headache, excessive sweating, soft-tissue swelling, joint disorders and, perhaps most striking, a progressive coarsening of facial features and enlargement of the hands, feet and jaw. According to the sixth edition of Basic & Clinical Endocrinology, untreated patients with acromegaly face a mortality rate two to four times higher than the average person due to such serious long-term complications as heart and respiratory diseases, diabetes and some forms of cancer.
Traditional treatments for acromegaly include surgery to remove the pituitary tumor, radiation therapy and pharmaceutical treatments.
The drug used in the study is Sensus Drug Development Corporation’s SOMAVERT® brand of pegvisomant. Sensus was acquired by Pharmacia Corporation in March 2001. Pharmacia has prepared regulatory filings for approval of SOMAVERT in the U.S. and Europe.
Journal
The Lancet