AbbVie Presents First Phase 1 Data Evaluating Novel ADC Candidate ABT-414 in Glioblastoma-
-Genentech Presents Preliminary Phase 2 Results Evaluating Two ADC Candidates, Polatuzumab Vedotin and Pinatuzumab Vedotin, in Relapsed/Refractory Non-Hodgkin Lymphoma-

CHICAGO, IL, USA I May 31, 2014 I Seattle Genetics, Inc. (Nasdaq:SGEN) today announced data from several collaborator antibody-drug conjugate (ADC) programs presented at the American Society of Clinical Oncology (ASCO) 50th Annual Meeting being held May 30 to June 3, 2014 in Chicago, IL. AbbVie presented preliminary data from an ongoing phase 1 clinical trial evaluating the ADC ABT-414 in combination with temozolomide in glioblastoma, and Genentech, a member of the Roche Group, is presenting data from five ADC programs, including two oral presentations. In addition, Progenics presented data from an ADC program under evaluation for castration-resistant prostate cancer. All of the collaborator programs utilize Seattle Genetics’ ADC technology.

“Researchers at Seattle Genetics have identified and optimized novel components that are fundamental to creating antibody-drug conjugates, including potent cell-killing agents and conditionally stable linker systems”

“Researchers at Seattle Genetics have identified and optimized novel components that are fundamental to creating antibody-drug conjugates, including potent cell-killing agents and conditionally stable linker systems,” said Jonathan Drachman, M.D., Chief Medical Officer and Executive Vice President, Research and Development at Seattle Genetics. “Our collaborators are making great progress in advancing novel ADC candidates as evidenced by the encouraging data presentations at ASCO. Seattle Genetics continues to lead the field in developing ADC candidates, which demonstrate the therapeutic potential of our technology broadly through both our proprietary and collaborator programs.”

With over 16 years of experience and knowledge in ADC innovation, Seattle Genetics is the leader in developing ADCs, a technology designed to harness the targeting ability of antibodies to deliver cell-killing agents directly to cancer cells. Of the more than 30 ADC candidates in clinical development, greater than 20 utilize Seattle Genetics’ proprietary ADC technology. Seattle Genetics and its collaborators, including Genentech, AbbVie and Progenics, have nine data presentations at ASCO that highlight the widespread evaluation of its ADC technology to potentially impact the way cancer is treated.

AbbVie

A phase 1 study evaluating ABT-414 in combination with temozolomide for subjects with recurrent or unresectable glioblastoma (Abstract #2021, poster presentation Friday, May 30th, 1:00-4:00 p.m. Central Time [CT])

A phase 1 clinical trial is being conducted by AbbVie to evaluate the safety and efficacy of ABT-414 in combination with temozolomide in patients with recurrent or unresectable glioblastoma. ABT-414 is an ADC consisting of a unique antibody targeting epidermal growth factor receptor (EGFR) conjugated to the cytotoxic agent monomethyl auristatin F (MMAF) using Seattle Genetics’ ADC technology. Preliminary results from an ongoing phase 1 clinical trial were reported evaluating the safety, activity and recommended phase 2 dose of ABT-414 when administered every other week in combination with temozolomide. In this preliminary analysis, 21 patients were evaluable for safety and 15 patients were evaluable for efficacy.

ABT-414 in combination with temozolomide demonstrated antitumor activity in the treatment of glioblastoma. In the preliminary analysis, 15 patients with measurable disease at baseline were assessed for best response on study and four patients experienced an objective response, including one complete response and three partial responses. Thirteen patients remained on therapy at the time of data analysis. The recommended phase 2 dose was determined to be 1.25 milligrams per kilogram (mg/kg) in combination with temozolomide. Adverse events of all grades occurring in more than three patients included blurred vision (43 percent), nausea (33 percent) and fatigue and headache (29 percent each). The only Grade 3 or 4 adverse event occurring in more than one patient was keratitis (10 percent). The phase 1 study is ongoing and phase 2 studies are being planned.

Genentech

Preliminary results of a phase II randomized study (ROMULUS) of polatuzumab vedotin or pinatuzumab vedotin plus rituximab in patients with relapsed/refractory non-Hodgkin lymphoma (Abstract #8519, oral presentation Saturday, May 31st at 1:39 p.m. CT)

Polatuzumab vedotin (anti-CD79b) and pinatuzumab vedotin (anti-CD22) are ADCs being developed by Genentech consisting of an anti-CD79b or anti-CD22 monoclonal antibody conjugated to the cytotoxic agent monomethyl auristatin E (MMAE) using Seattle Genetics’ ADC technology. Preliminary results from an ongoing phase 2 clinical trial were reported evaluating the activity and safety of polatuzumab vedotin or pinatuzumab vedotin plus rituximab in 59 and 63 patients, respectively, with relapsed or refractory non-Hodgkin lymphoma (NHL).

Both polatuzumab vedotin and pinatuzumab vedotin demonstrated antitumor activity with similar and generally acceptable safety profiles. In the analysis, durable responses were observed in both diffuse large b-cell lymphoma (DLBCL) and follicular lymphoma, including patients who were refractory to rituximab and/or their most recent therapy. Treatment with polatuzumab vedotin plus rituximab demonstrated an objective response of 56 percent (22 of 39 patients) in DLBCL and 70 percent (14 of 20 patients) in follicular lymphoma. Treatment with pinatuzumab vedotin plus rituximab demonstrated an objective response of 57 percent (24 of 42 patients) in DLBCL and 62 percent (13 of 21 patients) in follicular lymphoma. The phase 2 study is ongoing and further studies evaluating polatuzumab vedotin combined with chemotherapy are planned.

A phase I study of DNIB0600A, an antibody-drug conjugate targeting NaPi2b, in patients with non-small cell lung cancer or platinum-resistant ovarian cancer (Abstract #2504, oral presentation Saturday, May 31st at 2:27 p.m. CT)

A phase 1 clinical trial is being conducted by Genentech to evaluate the safety and activity of DNIB0600A in patients with non-small cell lung cancer (NSCLC) or platinum-resistant ovarian cancer (OC). DNIB0600A is an ADC consisting of an anti-NaPi2b monoclonal antibody conjugated to the cytotoxic agent MMAE using Seattle Genetics’ ADC technology. In this analysis, 49 patients were evaluable (18 OC, 31 NSCLC) all treated at the recommended phase 2 dose level of 2.4 mg/kg every three weeks. DNIB0600A demonstrated antitumor activity with an encouraging safety profile. Confirmed partial responses were observed in 41 percent (seven of 17 patients) of IHC 2/3+ OC patients and 10 percent (two of 21 patients) of IHC 2/3+ NSCLC patients. Phase 1 studies in lung and ovarian cancer, and a phase 2 study in ovarian cancer are currently ongoing.

Additional Collaborator Presentations

Additional collaborator presentations are included below and full abstracts can be accessed on the ASCO website at abstracts.asco.org.

  • A phase I study of DMOT4039A, an antibody-drug conjugate targeting mesothelin, in patients with unresectable pancreatic or platinum-resistant ovarian cancer (Genentech; Abstract #2529, poster presentation Friday, May 30th, 1:00-4:00 p.m. CT )
  • A phase I study of DSTP3086S, an antibody-drug conjugate targeting STEAP-1, in patients with metastatic castration-resistant prostate cancer (Genentech; Abstract #5024, poster presentation Saturday, May 31st, 1:15-4:15 p.m. CT)
  • A phase 2 trial of prostate-specific membrane antigen antibody-drug conjugate (PSMA ADC) in taxane-refractory metastatic castration-resistant prostate cancer (Progenics; Abstract #5023, poster presentation Saturday, May 31st, 1:15-4:15 p.m. CT)

About Seattle Genetics

Seattle Genetics is a biotechnology company focused on the development and commercialization of innovative antibody-based therapies for the treatment of cancer. Seattle Genetics is leading the field in developing antibody-drug conjugates (ADCs), a technology designed to harness the targeting ability of antibodies to deliver cell-killing agents directly to cancer cells. The company’s lead product, ADCETRIS® (brentuximab vedotin) is an ADC that, in collaboration with Takeda Pharmaceutical Company Limited, is commercially available for two indications in 40 countries, including the U.S., Canada, Japan and members of the European Union. Additionally, ADCETRIS is being evaluated broadly in more than 30 ongoing clinical trials. Seattle Genetics is also advancing a robust pipeline of clinical-stage ADC programs, including SGN-CD19A, SGN-CD33A, SGN-LIV1A, ASG-22ME and ASG-15ME. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including AbbVie, Agensys (an affiliate of Astellas), Bayer, Genentech, GlaxoSmithKline and Pfizer. More information can be found at www.seattlegenetics.com.

SOURCE: Seattle Genetics