Zadaxin Shows Synergy With Nucleoside Analogue
SciClone Phase II Trial Data Positive For HBV TreatmentBy Randall Osborne
SciClone Pharmaceuticals Inc. disclosed clinically significant, positive results from a Phase II trial of Zadaxin (thymosin alpha 1) plus famciclovir, a nucleoside analogue, in chronic hepatitis B patients.
In the study, conducted in Hong Kong SAR, China, 68 asymptomatic, immune-tolerant hepatitis B patients - that is, patients whose immune systems do not reliably recognize the hepatitis B virus as harmful - were treated for six months with either Zadaxin plus famciclovir, famciclovir alone, or no treatment.
"We knew we could add it to interferon [as a therapy for] hepatitis C," said Shawn Singh, senior vice president of San Mateo, Calif.-based SciClone. "And in both diseases, we don't add side effects."
Of those receiving Zadaxin plus famciclovir, 9.4 percent - or three out of 32 - experienced seroconversion to hepatitis B e antigen negative, or the elimination of viral replication, after completion of the combination therapy and follow-up. The effect was not evident in any of the 22 patients treated with famciclovir alone or in the 14-patient untreated control group.
"E antigen is a viral protein particle that shows infectivity, and it must be present for the virus to replicate," Singh said.
Satisfying results put Zadaxin and famciclovir in a good position if combination therapy becomes the preferred method of attacking hepatitis B, he added.
"Our belief is that, gradually, [treatment] will move that way, as it has for AIDS and as it is for hepatitis C," Singh said. "They become resistant, and mutate, and probably no single drug is going to do it."
Phase III HBV Monotherapy Study Under Way
SciClone's exclusive Japanese partner, Schering-Plough K.K., a subsidiary of Madison, N.J.-based Schering-Plough Corp., is conducting a Phase III study of Zadaxin as a monotherapy for hepatitis B. The drug is approved in eight countries outside the U.S. for that indication, and generated $2.2 million in sales for SciClone last year.
In July, SciClone signed an agreement for an equity line of up to $32 million over a two-year period from institutional investors. Under the terms of the deal, the company is not required to draw down a minimum amount, but may take up to $4 million per quarter through stock sales. (See BioWorld Today, July 9, 1998, p. 1.)
Singh said the company has drawn down none of the money, although - like many biotechnology firms - SciClone has found fund-raising costly. "[The problem] is not really so much availability of capital, as cost of capital," he said.
In the Zadaxin-with-interferon program for hepatitis, he said, the company has finished one Phase III study. "We're looking to collaborate for the remaining development," he said.
The Phase II results in hepatitis B were disclosed at the joint meeting of the International Association for the Study of the Liver and for the Study of Liver Diseases, in Chicago.
SciClone's stock (NASDAQ:SCLN) closed Wednesday at $1.312, down $0.062. n