Oct 16 (Reuters) - A new type of cholesterol drug being developed by Regeneron Pharmaceuticals Inc and Sanofi SA, when used by itself, cut levels of "bad" LDL cholesterol almost in half in the first of a dozen late-stage trials of the injectable medicine.
The experimental drug, called alirocumab, is from a promising new class of injectable cholesterol fighters also being developed by Amgen Inc and other drugmakers. They work by blocking a naturally occurring protein called PCSK9 and could each garner annual sales of $3 billion or more, if approved, according to some industry analysts.
In earlier mid-stage studies, when combined with standard oral cholesterol drugs called statins such as Pfizer Inc's Lipitor, alirocumab and Amgen's AMG145 slashed levels of LDL cholesterol by close to 70 percent more than statins alone.
But the 103-patient Phase III study described on Wednesday involved patients who took alirocumab by itself, or who took only Merck & Co Inc's cholesterol fighter Zetia (ezetimibe) - a pill often used by patients who cannot tolerate statins.
Although patients enrolled in the Regeneron/Sanofi trial had high cholesterol levels, they were deemed to have only moderate cardiovascular risk due to the absence of many other risk factors.
Regeneron and Sanofi said LDL cholesterol levels fell 47 percent in those who gave themselves injections of low-dose alirocumab every two weeks over a 24-week period. Cholesterol levels fell 15.6 percent in those taking daily 10-milligram doses of Zetia over the same period.
George Yancopoulos, Regeneron's research chief, said no worrisome side effects were seen in the study and in earlier trials of alirocumab.
"What we're seeing in first Phase III trial of our drug is in line with what we saw in Phase II" trials, Yancopoulos said in an interview. "The good news here is there were no surprises, and that it supports the good efficacy and safety profile we've seen to date."
In the study, called Odyssey Mono, patients taking alirocumab started out with a low 75-milligram dose every two weeks. But their doses were increased to 150 milligrams at week 12 if their LDL levels at week eight were above 70.
About three-fourths of the patients remained on the low dose of alirocumab throughout the study because they got their LDL levels down to below 70 - an aggressive LDL target - by the eighth week of the study.
"It shows that a low dose, when used as a monotherapy, can be quite effective," Yancopoulos said.
Yancopoulos said Regeneron and Sanofi hope to seek regulatory approvals by late 2015 for their drug, for use by itself and with statins, after data from the remaining 11 late-stage trials of alirocumab are released. An estimated 23,000 patients are being studied in the various Phase III trials.
The Regeneron research chief said Amgen's rival drug might reach market soon after alirocumab, or even before. But he predicted neither drug would have much of an advantage by getting approved first.
"But we're hoping to have bragging rights for the first approval," Yancopoulos said.
Regeneron and Sanofi are hoping their new medicine will be a compelling treatment option for the estimated 1 million Americans who cannot tolerate statins and up to another 5 million Americans who have failed to drive down their cholesterol levels to desired levels with statins.
Analysts believe strong demand from outside the United States could also propel blockbuster sales of alirocumab and rival products.