By Lisa Seachrist
WASHINGTON — When the Dermatologic and Ophthalmic Drugs Advisory Committee convenes today, its agenda will lie solely with considering the risks and benefits of the first antisense therapy to be reviewed by the FDA for marketing approval.
Granted priority review for the drug in June, Isis Pharmaceuticals Inc., of Carlsbad, Calif., will be looking for the committee to support fomivirsen for treatment of cytomegalovirus (CMV) retinitis. Should that review result in a recommendation that ultimately leads to approval for the drug, it could mark the beginning for antisense treatment of diseases as well as Isis' likely domination of the approach.
"We are very excited to have fomivirsen at this stage in regulatory review," said Jane Green, senior director of investor relations for Isis. "We're very hopeful for approval in the end. Even though the market right now is very small, this is an important milestone for us."
Fomivirsen is an antisense DNA product designed to prevent CMV from replicating. As an injection directly into the eye, the drug is designed to combat CMV retinitis — a serious and debilitating complication of AIDS that ultimately leads to blindness.
With the advent of triple therapy including protease inhibitors for HIV-infected individuals, the incidence of CMV retinitis has dropped significantly. However, Green noted that as HIV begins to develop resistance to the new drug cocktails, the incidence of CMV retinitis is likely to increase once more.
"Unfortunately, the potential for seeing more people develop end stage AIDS is real," Green said.
It is likely, however, that approval of fomivirsen will raise Isis' profile in the investment community far beyond its ability to gain market share in CMV treatment.
David Stone, an analyst with Cowen & Co. in Boston, said by moving the first antisense drug onto the market, Isis will force investors to "suspend their disbelief" concerning the technology.
Antisense is a DNA molecule that blocks specific protein production by targeting messenger RNA. Because DNA naturally occurs in every cell, the body has developed a number of ways to destroy DNA that strays from areas where it belongs. As a result, developing antisense DNA molecules that can circulate through the body and still have a therapeutic effect has proved challenging.
In fact, several companies, such as Gilead Sciences, of Foster City, Calif., have all but abandoned their programs in antisense technology, Stone said, while Isis has developed the molecular chemistry to make antisense drugs more stable.
Nevertheless, fomivirsen is primarily a locally active compound because it is injected into the site of CMV infection.
Stone pointed out the company has an antisense drug to modulate inflammation in Crohn's disease in a pivotal trial and has begun clinical testing of an antisense product for the treatment of solid tumors. Both of those drugs act systemically.
"Isis has the patent estate and they are further along in their programs than their competitors," Stone said. "Approval of [fomivirsen] will primarily help Isis answer the skeptics."
Isis Stock (NASDAQ:ISIP) closed at $13.438, down $0.813. *