By Mary Welch

Pentose Pharmaceuticals, which develops antiviral technologies based on nucleic-acid chemistry, completed a $7 million private financing to advance through clinical trials Inactine, an antiviral product that inactivates viruses in blood products.

The company has one compound, Papirine, a topical antiviral, in Phase I/II trials, but the financing round will mainly fund the start of Phase I trials for Inactine products, which are small-molecule, electrophilic compounds that selectively bind and irreversibly modify nucleic acids, thereby preventing viral replication.

"We intend to pursue a very aggressive schedule for Inactine and hopefully file an IND [investigational new drug] application in 1999," said Martin Williams, vice president of business development, sales and marketing for Cambridge, Mass.-based Pentose. "There is a massive opportunity for its use, and we believe we will be answering a public health cry for safe blood transfusions."

Each year, about 44 million units of red blood cell concentrates are transfused into patients around the world, including about 12 million in the U.S. While some viruses can be screened, such as HIV, hepatitis C, and human T cell lymphotrophic virus, many cannot.

"Essentially, Inactine binds to the nucleic acid inside the virus and renders it non-infectious," Williams said. "Its unique advantage is that it kills the virus - it destroys it. Even the hidden viruses are killed."

After the blood is treated with Inactine, the chemicals are removed, leaving the blood "pure and safe," he said. There are no side effects, and Inactine does not disrupt or destroy the blood's structure or important macro-molecules, such as plasma proteins that include human serum albumin and clotting factors.

Would-be collaborators, Williams said, are "beating a path to our door. There's a huge opportunity here with Inactine."

While Inactine's clinical progress will consume much of the funding, the company also is actively pursuing the Papirine family of compounds, made up of small-molecule drugs with broad-spectrum antiviral activity, designed to act through a natural antiviral pathway induced by interferon.

The gel is a topical drug for infections caused by human papillomavirus (HPV). Currently the company is undertaking three trials with Papirine. Two (one in the U.S., the other Europe) are for external genital warts; the other, conducted in the U.S., is for skin warts, such as those found on hands and feet. So far, about 230 patients have been treated.

"Warts really are very interesting," said Williams. "They are little viruses, and highly contagious." Papirine destroys the virus inside the cells, which prevents further cell growth.

Genital warts, a form of HPV, is the most prevalent sexually transmitted disease in the world. "They're difficult to treat and get rid of," Williams said, adding that Papirine is less irritating than existing treatments and is well-tolerated. "It has a clean profile," he said.

The three-year-old company is investigating Papirine against other indications caused by HPV, including herpes and cervical cancer. Pentose anticipates the need for raising more money this year, either by a private placement or by going public, Williams added.

"That really depends on the health of the financial market, and that's out of our control," he said.

Jafco Co. Ltd., of Tokyo, is a new investor in the financing. Ampersand Ventures of Wellesley, Mass., which was Pentose's seed investor, also participated. Ampersand now has a "fairly large share," of Pentose, Williams said. *