Seattle Genetics Announces Clinical Collaboration To Expand The Therapeutic Evaluation Of SGN-LIV1A In Triple Negative Breast Cancer

SGN-LIV1A to be Investigated in Combination with Atezolizumab as Part of Initiative for the Development of Novel Cancer Immunotherapy Combinations

BOTHELL, Wash.--(BUSINESS WIRE)--Seattle Genetics, Inc. (Nasdaq: SGEN), a global biotechnology company, today announced a clinical collaboration agreement with Genentech, a member of the Roche Group, for the evaluation of its investigational antibody-drug conjugate (ADC) SGN-LIV1A in combination with atezolizumab (TECENTRIQ^®) in patients with metastatic triple-negative breast cancer (TNBC). SGN-LIV1A, one of four clinical-stage treatments under development by Seattle Genetics for solid tumors, consists of a LIV-1 targeted monoclonal antibody linked to the potent cell-killing agent monomethyl auristatin E (MMAE). Breast cancer is the most common cancer among women worldwide, with an estimated 1.7 million new cases per year. About 15 to 20 percent of breast cancers are triple negative, which means they lack expression of three breast cancer-associated proteins that serve as key therapeutic targets.

“We have phase 1 data showing that SGN-LIV1A is active as monotherapy in patients with heavily pretreated, metastatic TNBC. Now, under this new collaboration, we will evaluate the potential to expand therapeutic benefit to these patients through combination therapy with atezolizumab.”

“A key challenge in triple-negative breast cancer, or TNBC, is the lack of available novel targeted treatments. People with this disease generally have poor prognoses. Moreover, current therapies are not curative and only delay disease progression,” said Robert Lechleider, M.D., Senior Vice President, Clinical Development of Seattle Genetics. “We have phase 1 data showing that SGN-LIV1A is active as monotherapy in patients with heavily pretreated, metastatic TNBC. Now, under this new collaboration, we will evaluate the potential to expand therapeutic benefit to these patients through combination therapy with atezolizumab.”

SGN-LIV1A administered in combination with atezolizumab will be evaluated in a phase 1b/2 clinical study as second-line therapy in patients with metastatic TNBC who have not been previously treated with immunotherapy. This randomized, controlled study is anticipated to enroll up to 45 patients in the treatment arm. Seattle Genetics and Genentech will test the experimental combination in MORPHEUS, Roche’s Novel Cancer Immunotherapy Development Platform. MORPHEUS is a phase 1b/2 adaptive platform to develop combinations of cancer immunotherapies rapidly and efficiently.

Under the terms of the collaboration agreement, Genentech will manage the study operations for the phase 1b/2 trial. Seattle Genetics will retain global development and commercialization rights to SGN-LIV1A.

About SGN-LIV1A

SGN-LIV1A is a novel investigational ADC targeted to LIV-1 protein utilizing Seattle Genetics’ proprietary ADC technology. LIV-1 is expressed by most metastatic breast cancers. It has also been detected in a number of other cancers, including melanoma, prostate, ovarian, and cervical cancer. SGN-LIV1A consists of a LIV-1-targeted monoclonal antibody linked to a potent microtubule-disrupting agent, monomethyl auristatin E (MMAE) by a protease-cleavable linker, using the same technology as ADCETRIS (brentuximab vedotin). It is designed to bind to LIV-1 on cancer cells and release the cell-killing agent into target cells upon internalization. SGN-LIV1A may also cause antitumor activity through other mechanisms, including activation of an immune response.

TECENTRIQ^® (atezolizumab) is a registered trademark of Genentech, a member of the Roche Group.

About Seattle Genetics

Seattle Genetics is an innovative biotechnology company that develops and commercializes novel antibody-based therapies for the treatment of cancer. The company’s industry-leading antibody-drug conjugate (ADC) technology harnesses the targeting ability of antibodies to deliver cell-killing agents directly to cancer cells. ADCETRIS^® (brentuximab vedotin), the company’s lead product, in collaboration with Takeda Pharmaceutical Company Limited, is the first in a new class of ADCs commercially available globally in 67 countries for relapsed classical Hodgkin lymphoma and relapsed systemic anaplastic large cell lymphoma (sALCL). Seattle Genetics is also advancing enfortumab vedotin, an ADC for metastatic urothelial cancer, in a planned pivotal trial in collaboration with Astellas. Headquartered in Bothell, Washington, Seattle Genetics has a strong pipeline of innovative therapies for blood-related cancers and solid tumors designed to address significant unmet medical needs and improve treatment outcomes for patients. The company has collaborations for its proprietary ADC technology with a number of companies including AbbVie, Astellas, Bayer, Celldex, Genentech, GlaxoSmithKline and Pfizer. More information can be found at www.seattlegenetics.com

Forward Looking Statements

Certain of the statements made in this press release are forward looking, such as those, among others, relating to the therapeutic potential of SGN-LIV1A and its possible benefits and uses, as monotherapy or in combination with atezolizumab. 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 the inability of SGN-LIV1A to show sufficient activity in the clinical setting referenced above and the risk of adverse events of SGN-LIV1A alone or in combination with atezolizumab. More information about the risks and uncertainties faced by Seattle Genetics is contained under the caption “Risk Factors” included in the company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2017 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.