By Randall Osborne

With marketing partners and commercial-scale manufacturing in place, Lidak Pharmaceuticals Inc. submitted its new drug application (NDA) to the FDA for Lidakol, a topical cream, as a treatment for oral herpes.

In August, La Jolla, Calif.-based Lidak reported positive Phase III trial results with Lidakol, a long-chained fatty alcohol that acts by interfering with viral entry into target cells. Other treatments attack the virus when it already has penetrated the cells. Lidakol reduced the healing time of herpes episodes to a statistically significant degree. (See BioWorld Today, Aug. 18, 1997, p. 1.)

Lidak's road to an NDA for the herpes drug has been difficult — not because the drug didn't work, but because an adequate placebo could not immediately be formulated, said Lisa Katz, director of corporate communications and investor relations at Lidak.

"The active compound [in Lidakol] is very dense, almost like wax, which is why nobody had looked at it," Katz said. However, blended with an inactive vehicle, "it made a very nice cream," she said.

"We were required to have a placebo that looked identical to our drug, and this is where we ran up against the problem," Katz continued. When scientists took the active compound out of the drug and added water or sugar to the vehicle, they ended up with a runny substance that did not resemble the original cream at all.

"We had a Catch-22 type of dilemma," Katz said.

The FDA allowed Lidak to use the vehicle with a substitute compound. Only one compound could be found that was believed to have no antiviral activity, Katz said. But when it was used as a placebo in the Phase III trials in 1996, the compound turned out to show activity after all.

For Lidak, this was good and bad news. It was good news because the company had discovered a new antiviral compound, for which it has since sought patent protection and refuses to disclose. It was bad news because the active placebo made results from the Phase III trial of Lidakol worthless for an NDA.

Shown the data, the FDA allowed Lidak to use in the next Phase III trials an inert, alternative placebo — the one that the company had proposed originally. With this placebo, "we got beautiful statistical significance and clinical benefit, with virtually no side effects," Katz said. "The FDA has told us it's sufficient to support our filing."

If approved, Lidakol will be marketed in North America by Bristol-Myers Squibb Co., of New York; in Europe and certain African and Middle Eastern countries by Yamanouchi Europe BV, of the Netherlands; in Japan by Tokyo-based Grelan Pharmaceutical Co. Ltd.; in Israel by CTS Chemical Industries, of Kiryat Malachi; and in Korea by Boryung Pharma Co. Ltd., of Seoul. Yamanouchi Europe is a subsidiary of Yamanouchi Pharmaceutical Co. Ltd., of Tokyo.

Katz said the company hopes for approval of the drug within a year. The strong Phase III evidence from the most recent trials vindicates the company's faith in Lidakol, she said. "We never doubted it," Katz said.

Last Tuesday, when the NDA filing was made public, Lidak's stock (NASDAQ:LDAKA) closed at $2.093, up $0.187. *

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