News Release

Targeted Genetics Collaborators Report Additional Phase I E1A Gene Therapy Data At American Society of Clinical Oncology Meeting

Peer-Reviewed Publication

Noonan/Russo Communications

- Proprietary Gene Therapy Found To Downregulate Expression of HER-2/neu Oncogene -

LOS ANGELES, CA, MAY 18, 1998 - Targeted Genetics Corporation (Nasdaq: TGEN) today announced additional Phase I results of its E1A gene therapy for the treatment of breast and head and neck cancers at the 34th Annual Meeting of The American Society of Clinical Oncology (ASCO).

In a poster presentation titled "Phase I trial of intratumoral liposomal-E1A gene therapy in patients with recurrent/refractory breast cancer and head and neck cancer," researchers demonstrated intratumoral delivery of the E1A gene using a proprietary non-viral liposomal delivery mechanism, subsequent downregulation of HER-2/neu expression and tumor responses. E1A is a tumor inhibitor gene. Previous laboratory and animal studies have demonstrated E1A's ability to inhibit tumor growth and suppress metastases, induce apoptosis (programmed cell death) and reverse the overexpression of HER-2/neu, a cancer-causing gene. In patients with cancer, overexpression of the HER-2/neu oncogene is correlated with poor prognoses, increased metastasis and resistance to chemotherapeutic agents. In Phase I data presented earlier this year, Naoto Ueno, M.D., and colleagues at The University of Texas M.D. Anderson Cancer Center reported that in three of three patients with breast and ovarian cancer treated with E1A a downregulation of HER-2/neu was observed, suggesting that overexpression of HER-2/neu can be reversed by the injection of the E1A gene.

A team of researchers at M.D. Anderson Cancer Center led by James L. Murray, M.D., Professor of Medicine, Director Immunotherapy and Vaccine Program, along with colleagues at Targeted Genetics and Wayne State University, conducted the research presented at ASCO. The Phase I dose-escalation study treated nine patients with recurrent and unresectable breast cancer and nine patients with head and neck cancer. In 16 patients evaluable for response, nine had stable disease, five had progressive disease and two had minor responses in treated tumors despite tumor progression at other untreated sites. In one of six patients who had repeat biopsies of treated tumors, no pathologic evidence of tumor was found. In four of seven patients evaluated to date, evidence of down regulation of HER-2/neu was reported.

"This new data, along with Phase I data previously presented in March at the meeting of the American Association for Cancer Research, gives additional credence to the concept of using E1A gene therapy for a broad range of cancers," said H. Stewart Parker, President and CEO of Targeted Genetics. "We are extremely encouraged by this new data, which confirms previous findings of E1A's ability to downregulate the HER-2/neu oncogene. We remain on track to initiate Phase II studies for E1A in head and neck cancer in the second half of 1998."

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

This news release contains forward-looking statements that involve risks and uncertainties, including the timing and results of clinical trials and other product development and commercialization risks. Risks associated with liquidity, capital resources and other risks are detailed in Targeted Genetics' filings with the U.S. Securities and Exchange Commission (SEC).

Editor's Note:
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