News Release

Targeted Genetics presents clinical data on E1A cancer gene therapy

Peer-Reviewed Publication

Noonan/Russo Communications

Phase II data and summary of Phase I studies presented at ASCO

New Orleans, LA-May 22, 2000-Targeted Genetics Corporation (Nasdaq: TGEN) yesterday presented data from its clinical studies of tgDCC-E1A, the Company's lead cancer therapy, at the 36th American Society of Clinical Oncology Annual Meeting in New Orleans, Louisiana. Dr. Thomas C. Reynolds, Vice President, Clinical Affairs at Targeted Genetics, presented data from clinical trials of tgDCC-E1A in patients with head and neck cancer or ovarian cancer at a poster discussion session on the topic of Biologic Therapy for cancer. Preclinical data from studies of a systemic delivery formulation of E1A also were presented in the same poster.

Data from a recently completed Phase II study of tgDCC-E1A in recurrent head and neck squamous cell carcinoma (HNSCC) were presented in an abstract titled "Activity of E1A in Human Clinical Trials." The Phase II study evaluated tgDCC-E1A as single-agent therapy in 24 patients with recurrent HNSCC. Patients received 30ug DNA/cm3 of tumor via intratumoral injection daily for three days and then weekly for seven weeks. The most common side effect was pain at the injection site, and no serious adverse events related to tgDCC-E1A were reported. Of 20 evaluable patients, 45% showed objective responses or stabilization of their disease as assessed by CT analysis. A 5% complete response rate also was observed by the same criteria. Tumor response was determined as a function of tumor growth measured by physical exam and by two-dimensional and three-dimensional CT analysis.

"These data suggest that tgDCC-E1A is safe and will be useful in the treatment of head and neck cancer," said Dr. Reynolds. "Although patients in this study had very advanced disease, we were able to generate a 45% response rate using tgDCC-E1A as a single agent. Preclinical studies show that E1A can sensitize tumors to radiation and chemotherapy and we believe that combination therapy may provide even better response rates. We intend to initiate a Phase II study in combination with radiation in HNSCC later this year in order to determine the most effective application of tgDCC-E1A. This is consistent with our ongoing analysis of tgDCC-E1A in combination with chemotherapy to treat ovarian cancer. We also expect to undertake additional Phase I studies of E1A in other cancer indications in the same timeframe."

An ongoing Phase I study of tgDCC-E1A in combination with paclitaxel and cisplatin in ovarian cancer also was described in the poster. This open label, dose-escalation study, initiated in December 1999, is designed to evaluate safety and establish the maximum tolerated dose of combination therapy in this patient population. Biological effect, tumor response and pharmacokinetic responses also will be evaluated.

Data from preclinical studies of tgLPD-E1A, a formulation for systemic delivery, also were presented in the same abstract. In these studies, tgLPD-E1A reduced tumor growth in a xenograft model of breast cancer, and the combination of tgLPD-E1A and paclitaxel and cisplatin almost completely inhibited tumor growth. In a xenograft model of head and neck tumors, 70% of animals receiving tgLPD-E1A as a single agent survived, as compared to 10% survival in the liposome alone or 5-Fluorouracil-treated groups. These data were also presented in April at the American Association of Cancer Research 91st Annual Meeting .

"We are building a strong franchise around our E1A technology," said H. Stewart Parker, President and Chief Executive Officer of Targeted Genetics. "tgLPD-E1A has generated some very exciting data in preclinical studies and we anticipate that we will initiate Phase I trials of this formulation in 2001. The ability of E1A to sensitize tumor cells to chemotherapy and radiation and our ability to deliver it via intratumoral injection or the intracavitary or intravenous route should provide multiple product opportunities. E1A may provide new treatment options to patients who do not benefit from existing regimens."

Previous laboratory and animal studies have demonstrated the ability of E1A to suppress metastases, increase sensitization to chemotherapeutic agents, increase sensitization to radiation, induce apoptosis (programmed cell death) and reverse malignant properties, including the over-expression of HER-2/neu. In patients with cancer, over-expression of the HER-2/neu oncogene is correlated with poor prognosis, increased tumor formation and metastasis and resistance to chemotherapeutic agents.

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Targeted Genetics Corporation develops gene therapy products for the treatment of acquired and inherited diseases. The company has lead clinical product development programs targeting cystic fibrosis and cancer, and a promising preclinical pipeline of product candidates focused on hemophilia A, arthritis, cancer and AIDS prophylaxis. The company has a broad platform of gene delivery technologies, as well as a promising body of technology for cellular therapy. For more information about Targeted Genetics Corporation please visit the Company's web site at http://www.targetedgenetics.com.

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 Quarterly Report on Form 10-Q 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.

Abstract # 1809
T.C. Reynolds
Poster Discussion
Sunday, May 21, 2000 1PM

Contact:

Targeted Genetics Corporation
Stephanie Seiler, Ph.D.
Director, Communications
(206) 521-7823

Noonan/Russo Communications
Page Sargisson (media)
(415) 677-4455, ext. 229
Mary Claire Bice (investors)
(212) 696-4455, ext. 238


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