Friday, Dec 19, 1997

Genentech Announces Phase III Investigational Trial Results

Preliminary results support new investigational approach in fighting breast cancer

South San Francisco, Calif. -- December 19, 1997 --

Genentech, Inc. (NYSE: GNE) today announced favorable preliminary results of Phase III clinical trials of its Herceptin (trastuzumab) anti-HER2 monoclonal antibody in women with metastatic breast cancer who overexpress the HER2 oncogene. This investigational drug offers a new biologic approach for the treatment of HER2 overexpressing metastatic breast cancer, an aggressive form of the disease that affects 25-30 percent of patients.

"These results have shown that the anticancer activity of the investigational Herceptin monoclonal antibody may result in both slowing the progression of the cancer and increasing the percentage of women who experience tumor shrinkage," said Arthur D. Levinson, Ph.D., Genentech's president and chief executive officer. "Although not a cure, these encouraging results in women with metastatic breast cancer suggest that better control of the disease may be possible. We are preparing these data as quickly as possible for review by the Food and Drug Administration and expect to submit a filing in the second quarter of 1998," said Levinson.

A large, randomized, controlled Phase III trial evaluated the efficacy and safety of adding Herceptin to initial treatment with chemotherapy regimens -- paclitaxel or anthracycline plus cyclophosphamide -- compared to treatment with either of these chemotherapy regimens alone. The study included 469 women with metastatic disease (cancer spread outside the breast) who had not previously been treated with chemotherapy for their metastatic disease. The preliminary analysis of this study indicates that adding Herceptin to chemotherapy did increase the clinical benefit by slowing the progression of the cancer and increasing tumor shrinkage. Further review of cancer progression and tumor shrinkage by an independent Response Evaluation Committee and analysis of response duration, time to treatment failure, quality of life and survival are in progress.

A second, large trial evaluated the efficacy and safety of Herceptin treatment used as a single agent (without chemotherapy) in 222 women with HER2 overexpressing metastatic breast cancer who had relapsed following treatment with one or two prior chemotherapy regimens. A clinical benefit appears to be present in this study as well.

Overall, the most common adverse events related to Herceptin were chills and fever, most often infusion-related. An increased risk of cardiac dysfunction was observed in women treated at the same time with Herceptin and anthracyclines compared to women receiving anthracyclines alone. This syndrome of cardiac dysfunction is similar to that previously observed with anthracycline treatment. This side effect can be potentially severe or life-threatening, and may suggest that some patients should not be treated with the antibody and anthracyclines at the same time. In a limited number of patients, there did not appear to be a large increased risk of cardiac dysfunction in women receiving Herceptin with paclitaxel or Herceptin as a single agent. Detailed analysis of the safety profile is ongoing and will be submitted to the FDA when complete.

Genentech will work with the clinical trial investigators to prepare and submit the final analyses of efficacy and safety for presentation at an upcoming scientific meeting and for publication in a peer-reviewed medical journal.

In 1995, Genentech, in cooperation with several breast cancer patient advocates, designed an expanded access program for severely ill breast cancer patients who have few or no other treatment options. Because of a limited supply of this investigational drug, Genentech and the breast cancer patient advocates designed a lottery system to assure an unbiased selection process. Those eligible for the expanded access program include women with tumors that overexpress HER2 and who have experienced disease progression following three or more chemotherapy regimens.

Genentech plans to have an additional, although still limited, supply of Herceptin in February 1998 when additional investigational drug currently being manufactured is available. Genentech expects to be able to quadruple the size of its current expanded access program for severely ill breast cancer patients so that 100 women per quarter will receive the investigational antibody. Details concerning expansion of the expanded access program will be announced in January 1998. Genentech anticipates adequate supply of Herceptin by the Fall of 1998. Physicians interested in the expanded access program should contact Genentech for more information.

The National Cancer Institute (NCI) has agreed to partner with Genentech to increase the geographic availability of the expanded access program for eligible breast cancer patients through its Treatment Referral Center Program, which includes cancer centers across the United States. It is anticipated that some participating NCI sites will be ready to accept patients for the expanded access program in February 1998. Because of the limited supply of the investigational antibody, only breast cancer patients who have metastatic disease and have not responded to standard therapies will be eligible for the expanded access program. "New approaches to treating advanced breast cancer are clearly needed and this represents a novel and rational attempt to benefit these patients. We are encouraged by the trial results for this new investigational agent and are pleased to help eligible patients gain access during the period of license application and FDA review. We need to understand more clearly both the benefits of this investigational therapy in advanced breast cancer and its potential utility in early stage disease," said Richard Klausner, MD, Director, National Cancer Institute.

NCI will also collaborate with Genentech in an expanded clinical research program to further define the role of the HER2 antibody in the treatment of breast cancer and to explore treatment of other relevant tumors with this novel investigational agent. New clinical trials of Herceptin in women with breast cancer will begin in the Spring.

Researchers, investigators and other leading oncologists, breast cancer patient advocates and the NCI have been instrumental in assisting Genentech in designing, enrolling and conducting clinical trials of this potential new investigational drug.

Approximately 25-30 percent of women with breast cancer have cancers that overexpress the HER2 oncogene, which is associated with more rapid cancer progression. Herceptin, a humanized HER2 antibody, works by binding to the HER2 growth factor receptors present in excessive amounts on the surface of the cancer cells. Clinical studies were based on laboratory experiments showing that the growth of HER2-overexpressing human breast cancer cells is slowed by Herceptin treatment.

There are approximately 180,000 women in the United States who will be diagnosed with breast cancer in any given year, and approximately 40 percent will eventually develop metastatic cancer. One in eight U.S. women will develop breast cancer in her lifetime.

Genentech, Inc. is a leading biotechnology company that discovers, develops, manufactures and markets human pharmaceuticals for significant unmet medical needs. Eleven of the currently marketed biotechnology products stem from Genentech science, eight of which Genentech markets or promotes directly in the United States. The company has headquarters in South San Francisco and is traded on the New York Stock Exchange and Pacific Exchange under the symbol GNE.

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