By Matthew Willett

SkyePharma plc and marketing partner Chiron Corp. said they will re-launch DepoCyt, their injectable, sustained-release chemotherapeutic, with the FDA's blessing after a 16-month hiatus.

The companies removed DepoCyt from the market in October 1999 after discovering batches that did not meet regulatory specifications. Chiron, of Emeryville, Calif., partnered with DepoTech Corp. for rights to DepoCyt in April 1994.

London-based SkyePharma acquired the drug through its $56 million acquisition of DepoTech, announced in late 1998. (See BioWorld Today, Oct. 20, 1998.)

Maurice Wolin, Chiron's vice president of oncology development, said the issue was never one of safety. The withdrawal focused instead on regulatory concerns in manufacturing, he said.

"The drug is cytarabine encapsulated in a foam-like matter, DepoFoam, which is what allows the drug to be given on an infrequent basis, its major advantage," Wolin told BioWorld Today. "In the manufacturing process there were problems with one of the raw materials, to my understanding, which led to a failing in the specifications set by the FDA. Those problems are now solved, and the FDA is now satisfied with the new manufacturing process and the raw materials being used."

Wolin downplayed the halt in production from a safety standpoint. He said there never was a serious health risk posed.

"There were patients who received drugs from the recall batches, but there were no adverse reactions," he said. "This was strictly a regulatory problem, not a health risk at all."

DepoCyt is an injectable, sustained-release formulation of the chemotherapeutic agent cytarabine. It is delivered by a DepoTech-developed lipid-based encapsulation system, DepoFoam, and injected every two weeks directly into the cerebrospinal fluid as a treatment for neoplastic meningitis.

The drug has had its share of by setbacks. Considered a "shoo-in" for approval in 1997, DepoCyt was deemed non-approvable in 1998. The FDA cited a lack of statistically significant evidence of superiority to methotrexate. (See BioWorld Today, May 27, 1998.)

Just six months later, however, DepoCyt won approval for treatment of lymphomatous meningitis. (See BioWorld Today, March 6, 1999.)

The re-launch is a positive for Chiron, though it will not be among its most significant products, according to Eric Schmidt, an analyst with SG Cowen Securities Corp. in New York.

"I don't think it's particularly important," Schmidt said. "It's a relatively small product, certainly a niche product, and though sales were undisclosed for the period it was on the market in 1999, we estimate the ultimate market opportunity is still in the $50 million to $100 million range at best, and Chiron would, the way the deal works with SkyePharma, roughly split the revenue with SkyePharma."

For marketing rights outside the U.S., Pharmacia & Upjohn (now Pharmacia Corp.) paid DepoTech $19 million in 1997. (See BioWorld Today, July 8, 1997.)

Wolin said there are about 6,000 cases of lymphomatous meningitis annually, but that the expansion of the therapeutic toward approval for the treatment of neoplastic meningitis from lymphomas is the company's ace in the hole for DepoCyt.

Partner SkyePharma is responsible for development in that indication, and Wolin said the program is in late-stage testing in preparation for regulatory submission.

Meanwhile, he said, the focus in on the re-launch. "My understanding is that we'll have product ready to ship within a week," he said.

Both companies' stocks gained on the news Friday. Chiron's shares (NASDAQ:CHIR) rose 37.5 cents, closing at $47.187, and SkyePharma's stock (NASDAQ:SKYE) gained $1.312 to close at $15.437. n