Seattle Genetics Commences Two Phase I Trials of SGN-CD19A

Seattle Genetics, Inc. (Nasdaq: SGEN) today announced the initiation of twophase I clinical trials of SGN-CD19A, one for patients with B-cell acutelymphoblastic leukemia (ALL) and one for patients with B-cell non-Hodgkinlymphomas. SGN-CD19A utilizes Seattle Genetics' industry-leading antibody-drugconjugate (ADC) technology. The trials are designed to assess the safety andantitumor activity of SGN-CD19A, an ADC targeted to CD19.“CD19 is expressed in a variety of hematologic malignancies, includingnon-Hodgkin lymphoma and ALL, and has limited expression on normal tissuesmaking it an ideal ADC target. Our preclinical data indicate that SGN-CD19Ainternalizes rapidly into tumor cells, resulting in targeted cell killing,”said Jonathan Drachman, M.D., Senior Vice President, Research andTranslational Medicine at Seattle Genetics. “Our SGN-CD19A clinicaldevelopment program comprises two trials that, together, will provide a robustunderstanding of the activity and tolerability of this ADC in patients withaggressive CD19-positive lymphomas or ALL. In addition to the five ADCsalready in ongoing clinical trials, we plan to advance two additional ADCprograms into the clinic during 2013, underscoring our leadership in thefield.”The studies are phase I, open-label, dose-escalation clinical trials. Theprimary endpoints are to estimate the maximum tolerated dose and to evaluatethe safety of SGN-CD19A. In addition, the trials will evaluate antitumoractivity, pharmacokinetics, progression-free survival and overall survival.One trial will enroll adult and pediatric patients with relapsed or refractoryB-cell ALL, as well as patients with Burkitt lymphoma or leukemia or B-celllymphoblastic lymphoma. The dose escalation portion of the study is designedto evaluate both weekly and every three week schedules and will enrollapproximately 80 patients at multiple centers in the United States. A secondtrial will enroll patients with relapsed or refractory aggressive B-cellnon-Hodgkin lymphomas, including diffuse large B-cell lymphoma (DLBCL) andmantle cell lymphoma. The dose escalation portion of the trial will evaluateSGN-CD19A administered every three weeks and will enroll approximately 25patients at multiple centers in the United States.Both trials permit additional patients to be enrolled into expansion cohortsfollowing determination of the maximum tolerated dose.For more information about the trials, including enrolling centers, pleasevisit www.clinicaltrials.gov.