Seattle Genetics Presents SGN-75 Clinical Data at ASCO Annual Meeting

CHICAGO--(BUSINESS WIRE)-- Seattle Genetics, Inc. (Nasdaq: SGEN) today announced the presentation of interim data from an ongoing phase I clinical trial of SGN-75 in renal cell carcinoma (RCC) and non-Hodgkin lymphoma at the American Society of Clinical Oncology (ASCO) 2011 Annual Meeting being held in Chicago, IL. SGN-75 is an antibody-drug conjugate (ADC) targeted to CD70. The interim data suggest that SGN-75 is generally well tolerated and induces objective responses in heavily pretreated RCC and non-Hodgkin lymphoma patients.

Among 25 RCC patients treated at escalating doses of SGN-75, two patients achieved a partial response, eight patients had stable disease, 11 patients had progressive disease and four patients were not evaluable for response. At doses of 2.0 milligrams per kilogram (mg/kg) and higher, two of nine patients with RCC who were evaluated for response achieved partial remissions lasting 23 weeks and 19+ weeks. Among 16 non-Hodgkin lymphoma patients treated with escalating doses of SGN-75, one patient with mantle cell lymphoma achieved a complete remission with duration of 31 weeks.

Two schedules of dose administration were tested in this study, a weekly dosing regimen and an every three week dosing regimen. The most common adverse events associated with SGN-75 treatment in the every three week dosing regimen were fatigue (30 percent), nausea (30 percent), dry eye (23 percent) and thrombocytopenia (23 percent). The maximum tolerated dose was determined to be 3.0 mg/kg every three weeks. Based on the observed ADC half life of six to 10 days, increased patient convenience and better safety profile, the every three week dosing schedule has been selected for further study. Enrollment of additional patients in up to 15-patient disease-specific cohorts is continuing at the 3.0 mg/kg every three week dose to further elucidate the safety and antitumor activity of SGN-75. (Abstract #3071)

“Despite the use of immunotherapy, tyrosine kinase inhibitors and mTOR inhibitors, many patients with kidney cancer ultimately experience progression of their disease,” said John A. Thompson, M.D., Professor, Medical Oncology, University of Washington School of Medicine and Seattle Cancer Care Alliance. “SGN-75 represents a novel approach to targeted therapy. These interim data with SGN-75 provide encouraging evidence of antitumor activity in some patients who had experienced treatment failure on other systemic therapies.”

About the SGN-75 Trial

Data were reported from 41 patients treated in the open-label, phase I clinical trial, including 25 with RCC and 16 with non-Hodgkin lymphoma. Cohorts of patients received SGN-75 on either an every three week basis at doses ranging from 0.3 to 4.5 mg/kg or on a weekly basis at doses ranging from 0.3 to 0.6 mg/kg. Enrolled patients in each indication had received a median of three prior systemic therapies.

The trial is evaluating the safety, tolerability, pharmacokinetic profile and antitumor activity of SGN-75. In addition, the trial was designed to establish a maximum tolerated dose and to identify a recommended administration schedule. Patients enrolled in the trial must have received at least one prior therapy and have confirmed CD70 expression.

SGN-75 is an ADC composed of an anti-CD70 antibody attached to a potent, synthetic cell-killing agent, monomethyl auristatin F (MMAF), using Seattle Genetics’ proprietary technology. The ADC is designed to be stable in the bloodstream, and to release its cell-killing agent upon internalization into CD70-expressing tumor cells. This approach is intended to spare non-targeted cells and thus reduce many of the toxic effects of traditional chemotherapy while enhancing the antitumor activity.

About Renal Cell Carcinoma

Renal cell carcinoma (RCC) forms in the kidney, which filters and cleans the blood. Metastatic RCC occurs when the cancer has spread to other parts of the body. RCC is the most common type of kidney cancer in adults, representing approximately 90 percent of cases. The American Cancer Society estimated that more than 58,000 new cases of kidney cancer were diagnosed in the United States during 2010, and approximately 13,000 people died from the disease.

About Non-Hodgkin Lymphoma

Non-Hodgkin lymphoma represents a diverse group of cancers that develop in the lymphatic system and are characterized by uncontrolled growth and accumulation of abnormal lymphocytes. Lymphocytes are white blood cells that are responsible for defending the body against infection. The most common forms of non-Hodgkin lymphoma are follicular and diffuse large B-cell lymphoma. According to the American Cancer Society, more than 65,000 cases of non-Hodgkin lymphoma were diagnosed in the United States during 2010 and more than 20,000 patients died from the disease.

About Seattle Genetics

Seattle Genetics is a clinical-stage biotechnology company focused on the development and commercialization of monoclonal antibody-based therapies for the treatment of cancer and autoimmune disease. The U.S. Food and Drug Administration has granted priority review to Biologics License Applications for its lead product candidate, brentuximab vedotin, for the treatment of relapsed or refractory Hodgkin lymphoma and relapsed or refractory systemic anaplastic large cell lymphoma, with a PDUFA date of August 30, 2011. Brentuximab vedotin is being developed in collaboration with Millennium: The Takeda Oncology Company. In addition, Seattle Genetics has four other clinical-stage programs: SGN-75, ASG-5ME, dacetuzumab (SGN-40) and SGN-70. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including Abbott, Bayer, Celldex Therapeutics, Daiichi Sankyo, Genentech, GlaxoSmithKline, Millennium, Pfizer and Progenics, as well as ADC co-development agreements with Agensys, an affiliate of Astellas, and Genmab. More information can be found at

Certain of the statements made in this press release are forward looking, such as those, among others, relating to the therapeutic potential and continuation of the ongoing phase I clinical trial of SGN-75. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include risks related to adverse medical events or inconclusive clinical trial results in the ongoing phase I clinical trial, including the inability to show that SGN-75 is effective or to show sufficient safety in such clinical trials, and risks related to Seattle Genetics’ ability to recruit and enroll a sufficient number of patients to participate in such clinical trials. More information about these and other risks and uncertainties faced by Seattle Genetics is contained under the heading “Risk Factors” in the company’s quarterly report on Form 10-Q for the quarter ended March 31, 2011 filed with the Securities and Exchange Commission. Seattle Genetics disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.


Seattle Genetics, Inc.
Peggy Pinkston, 425-527-4160
[email protected]

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