Hepatitis C and B Ribozyme Results Presented At AASLD

In panel discussions, plenary sessions and poster presentations at the annual AASLD (American Association for the Study of Liver Diseases) meeting this week, Dr. Lawrence M. Blatt, Vice President of Research at Ribozyme Pharmaceuticals, Inc. (RPI) (NASDAQ:RZYM), and other scientists presented information from collaborative studies of the company’s anti-Hepatitis C ribozyme, HEPTAZYMEâ„¢. RPI also presented results of pre-clinical studies of RPI’s anti-Hepatitis B ribozyme product candidates having demonstrated marked efficacy in animal models.

Hepatitis C

Results were reported from a single dose volunteer study as well as from multidose studies of HEPTAZYME administered by daily subcutaneous injections for 28 days to chronically infected Hepatitis C patients. These studies were designed to determine safety and tolerability and to examine pharmacokinetic characteristics of HEPTAZYME doses ranging from 0.3 mg to 90 mg per patient.

In both studies, HEPTAZYME was well-tolerated at all doses given. This is in contrast to the significant side effects associated with currently available HCV treatments. Additionally, the pharmacokinetic analysis demonstrated excellent bioavailability of HEPTAZYME and further supported the feasibility of self-administered daily subcutaneous injections. Safety and pharmacokinetic results from the studies of HEPTAZYME were similar to those seen in Phase I/II trials with ANGIOZYMEâ„¢, an anti-angiogenic ribozyme currently in development.

Further, in the multi-dose studies conducted at the Lilly Clinic and at the University of California at San Francisco, 12 HCV positive patients with elevations in serum ALT were treated at doses ranging from 10-90 mg/patient. Three of these patients had transient decreases in serum HCV RNA of approximately 1 log10.

“We are pleased that HEPTAZYME has performed as we had hoped within the constraints of the trial designs,” said Ralph E. Christoffersen, Ph.D., President & CEO of Ribozyme Pharmaceuticals, Inc. “Additionally, we are honored that several of the world’s top hepatologists will conduct HEPTAZYME Phase II clinical studies.”

To kick-off the upcoming HEPTAZYME Phase II clinical studies, an investigator meeting was held on Sunday, October 29, 2000 with the following clinicians: Dr. Myron Tong of the University of Southern California, Dr. Eugene Schiff of the University of Miami, Dr. Greg Everson of the University of Colorado at Denver, Dr. Don Jensen of Rush Presbyterian Hospital in Chicago, Dr. Steve Rossi of the University of California at San Francisco and Dr. John McHutchinson of Scripps Clinic.

Dr. Myron Tong, Principal Investigator of the HEPTAZYME Phase II trial and Chief of the Liver Center of Huntington Medical Research Institute in Pasadena, California and Professor of Medicine at the University of Southern California said, “HEPTAZYME represents an exciting new approach to specifically interrupt the replication of Hepatitis C virus, unlike present available treatments for this chronic illness. The ribozyme compound’s toxicity profile thus far is excellent in comparison to currently available drugs and should offer patients new hope for a cure for this disease. We are encouraged by the data on HEPTAZYME thus far and are looking forward to the upcoming clinical trials for treatment of chronic Hepatitis C patients.”

At the Presidential Plenary session held on Tuesday, October 31, 2000 studies of the antiviral effects of HEPTAZYME in a cell culture viral replication system (HCV/poliovirus chimera) were presented that showed a high correlation between reduction in viral RNA and antiviral effects as measured by a plaque assay. These studies demonstrate the ribozyme mechanism of action and support the potential of HEPTAZYME as a therapy for chronic Hepatitis C patients.

Hepatitis B

In addition, RPI reported in vivo activity of its anti-Hepatitis B ribozyme compounds. Using a murine model of Hepatitis B replication, studies demonstrated a statistically significant reduction in HBV viremia following subcutaneous administration of anti-HBV ribozymes. A dose related response was observed and the magnitude of antiviral effects was similar to those seen for the control group (Lamivudine®). This presentation from RPI was the recipient of the Presidents Choice Award at this year’s AASLD conference.

“These preliminary observations indicating a reduction of HBV viremia through the use of anti-HBV ribozymes are most encouraging. There remains a need for additional effective approaches to treatment in patients who have chronic Hepatitis B in whom there is inadequate response to currently available agents. Moreover, the dose response observed in the Hepatitis B ribozyme animal study informs the clinical dosing in the upcoming Hepatitis C trial. Taken in total, these two novel compounds represent a new approach for treatment of chronic viral Hepatitis,” said Dr. Willis Maddrey of the U.T. Southwestern Medical Center at Dallas, Senior Consultant to RPI.

Ribozymes are the product of Nobel Prize winning science and are synthetically engineered to act as “molecular scissors” capable of cleaving target RNA in a highly specific manner.

RPI (www.rpi.com), located in Boulder, Colorado, is the acknowledged leader in ribozyme therapeutic development. RPI has recently announced a ribozyme commercial development program to develop a ribozyme therapeutic against Hepatitis B. RPI is partnered with Chiron Corporation for the development and commercialization of ANGIOZYMEâ„¢, an anti-angiogenic ribozyme designed to inhibit the growth of new blood supplies to tumors and prevent tumor growth and metastasis. ANGIOZYME is in Phase I/II clinical trials in cancer patients at the Cleveland Clinic. RPI is also partnered with an affiliate of Elan Corporation plc for development of HERZYMEâ„¢, an anti-HER-2 ribozyme for treatment of breast and other cancers, through RPI’s subsidiary Medizyme Pharmaceuticals Ltd.

This press release contains forward-looking statements that involve risks and uncertainties, and actual events or results may differ materially. These risk factors include actions by the U.S. Food and Drug Administration, technological advances, ability to obtain rights to technology, ability to obtain and enforce patents, ability to commercialize and manufacture products and general economic conditions. These and additional risk factors are identified in RPI Securities and Exchange Commission filings, including the Forms 10-K and 10-Q and in other SEC filings.

FOR IMMEDIATE RELEASE
Contacts:
Ribozyme Pharmaceuticals, Inc.
Ralph E. Christoffersen, Ph.D.
CEO and President
(303) 449-6500
Freeman McCue Public Relations
Daniel McCue (714) 557-3663

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