Targeted Genetics Announces Positive Findings in Phase I/II Clinical Trial Testing Gene Therapy in Chronic Sinusitis in Cystic Fibrosis Patients
07:14 a.m. Mar 30, 1999 Eastern

SEATTLE, March 30 /PRNewswire/ -- Targeted Genetics Corporation today announced findings from a Phase I/II clinical trial of tgAAV-CF, the company's proprietary gene therapy product for the treatment of cystic fibrosis (CF). In this blinded, placebo-controlled trial, conducted at Stanford University, 23 cystic fibrosis patients were treated with tgAAV-CF in one maxillary sinus and with placebo in the other. There were no adverse events related to the test agent. Results from the study indicate that inflammation was reduced in sinuses treated with tgAAV-CF and not in sinuses treated with placebo. Full results of the study are being prepared for scientific review and publication.

"We are encouraged by this finding," said Darrell J. Salk, M.D., Vice President, Clinical Affairs at Targeted Genetics. "We have observed a biologic effect associated with treatment with our gene therapy product in a proposed model of CF lung disease. Because the degree of inflammation correlates with the amount of active disease, a reduction in inflammation is a positive sign. Further studies are clearly needed to assess the clinical impact of such an effect in CF lung disease. We are therefore moving forward expeditiously with Phase I testing of an aerosolized version of tgAAV-CF."

In December of 1998 Targeted Genetics announced that it had initiated a Phase I clinical trial for the treatment of CF lung disease using an aerosolized version of tgAAV-CF. Targeted Genetics is conducting the multi-center study in CF patients at Stanford University Medical Center and at two other centers in collaboration with the Cystic Fibrosis Foundation Therapeutics Development Center Network (TDN). This network includes seven specialized clinical research centers in the United States whose primary objective is to develop and conduct early-phase clinical trials of novel therapies for the treatment of CF. This Phase I study is being set up at TDN centers at the University of Washington in Seattle and at Children's Hospital in Boston, MA. The company intends to complete this study during 1999.

The trial, a dose-escalation, open-label study, will evaluate the safety of an aerosolized version of tgAAV-CF in patients with mild to moderate CF lung disease. The company believes that an aerosolized formulation will provide safe and widespread delivery of tgAAV-CF to the airways of the human lung and has the potential to alleviate the pulmonary symptoms associated with CF. Ultimately, the company expects its development partner, Medeva PLC, to take the aerosolized formulation of tgAAV-CF through the regulatory process for approval as a commercial product for the treatment of CF.

Phase I/II Maxillary Sinus Trial

The Phase I/II trial conducted at Stanford University included dose-escalation studies, previously reported, and the present study, designed to assess the safety and the effect of tgAAV-CF in preventing sinusitis in CF patients. Targeted Genetics' proprietary tgAAV-CF uses adeno-associated virus (AAV) to deliver a normal copy of the CFTR gene, which is non-functional in CF patients. A total of 23 patients were treated blindly with tgAAV-CF in one sinus and with placebo in the other. Patients were monitored for changes in a variety of serological markers, including detection of circulating vector and production of neutralizing antibodies that might inhibit the viral vector. Earlier results suggested that tgAAV-CF was safe and that there was evidence of gene transfer and long-term gene persistence (up to 70 days) in the maxillary sinus. Because sinus and lung infections in CF patients may both result from the same loss of CFTR function, the maxillary sinus in CF patients with chronic sinusitis and surgical antrostomy has been proposed as a test model for CF lung disease. Although sinusitis itself is not an intended indication for the product, the model has provided an opportunity to obtain important information about the safety and potential efficacy of tgAAV-CF sooner than would have been otherwise possible. Inherent complexities of the model did not allow the company to measure the impact of the product on the relapse of sinusitis. Further clinical trials involving direct administration of tgAAV-CF to the maxillary sinus are not anticipated at this time.

CF Background

CF results from the loss of function of the CFTR gene. Normally, the protein encoded by this gene is found in the respiratory passageways, pancreas, salivary and sweat glands where it helps to regulate the cellular concentration of chloride ions and water. In CF patients, the loss of this gene's function leads to the production and build-up in the lungs and sinuses of thick mucus, colonization by bacteria and the invasion of white blood cells, thus causing inflammation. These events produce scarring in the lung, which ultimately results in loss of respiratory function. It is estimated that 60,000 people worldwide have cystic fibrosis including approximately 24,000 people in the United States. The median age of survival for patients with CF is approximately 31 years.

Targeted Genetics Corporation develops gene and cell therapy products for the treatment of certain acquired and inherited diseases. The company has three lead product development programs targeting cystic fibrosis, cancer, and infectious disease, as well as an extensive technology platform.

NOTE: This release contains forward-looking statements relating to the Company's products under development, technologies and future operating results that are subject to certain risks and uncertainties that could cause actual results to differ materially from those projected. The words "believes," "expects," "intends," "anticipates," variations of such words, and similar expressions identify forward-looking statements, but their absence does not mean that the statement is not forward-looking. These statements are not guarantees of future performance and are subject to certain risks, uncertainties and assumptions that are difficult to predict. Factors that could affect the Company's actual results include the need for additional capital, the early stage of product development, uncertainties related to clinical trials, and uncertainties related to patent position. Reference is made to the Company's latest Annual Report on Form 10-K filed with the SEC for a more detailed description of such factors. Readers are cautioned not to place an undue reliance on these forward-looking statements, which speak only as of the date of this release. The Company undertakes no obligation to update publicly any forward-looking statements to reflect new information, events or circumstances after the date of this release or to reflect the occurrence of unanticipated events. SOURCE Targeted Genetics Corporation

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