Seattle Genetics, Inc. (Nasdaq: SGEN) today announced the initiation of two phase I clinical trials of SGN-CD19A, one for patients with B-cell acute lymphoblastic leukemia (ALL) and one for patients with B-cell non-Hodgkin lymphomas. SGN-CD19A utilizes Seattle Genetics’ industry-leading antibody-drug conjugate (ADC) technology. The trials are designed to assess the safety and antitumor activity of SGN-CD19A, an ADC targeted to CD19. “CD19 is expressed in a variety of hematologic malignancies, including non-Hodgkin lymphoma and ALL, and has limited expression on normal tissues making it an ideal ADC target. Our preclinical data indicate that SGN-CD19A internalizes rapidly into tumor cells, resulting in targeted cell killing,” said Jonathan Drachman, M.D., Senior Vice President, Research and Translational Medicine at Seattle Genetics. “Our SGN-CD19A clinical development program comprises two trials that, together, will provide a robust understanding of the activity and tolerability of this ADC in patients with aggressive CD19-positive lymphomas or ALL. In addition to the five ADCs already in ongoing clinical trials, we plan to advance two additional ADC programs into the clinic during 2013, underscoring our leadership in the field.” The studies are phase I, open-label, dose-escalation clinical trials. The primary endpoints are to estimate the maximum tolerated dose and to evaluate the safety of SGN-CD19A. In addition, the trials will evaluate antitumor activity, pharmacokinetics, progression-free survival and overall survival. One trial will enroll adult and pediatric patients with relapsed or refractory B-cell ALL, as well as patients with Burkitt lymphoma or leukemia or B-cell lymphoblastic lymphoma . The dose escalation portion of the study is designed to evaluate both weekly and every three week schedules and will enroll approximately 80 patients at multiple centers in the United States. A second trial will enroll patients with relapsed or refractory aggressive B-cell non-Hodgkin lymphomas, including diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma. The dose escalation portion of the trial will evaluate SGN-CD19A administered every three weeks and will enroll approximately 25 patients at multiple centers in the United States. Both trials permit additional patients to be enrolled into expansion cohorts following determination of the maximum tolerated dose.