Seattle Genetics preclinical data

In a mouse model of AML, a single dose of 300 µg/kg SGN-CD33A produced durable complete regressions in multidrug-resistant-positive and multidrug-resistant-negative cell lines. Additionally, a single dose of 1,000 µg/kg SGN-CD33A significantly delayed tumor growth compared to non-binding and untreated controls (p<0.001). A single dose of active control gemtuzumab ozogamicin was inactive up to 1,000 µg/kg. In mice negative for multidrug-resistant AML, a single dose of 33 µg/kg SGN-CD33A delayed tumor growth and a single dose of 100 µg/kg SGN-CD33A induced complete tumor regression. Seattle Genetics said gemtuzumab had "minimal activity" at 100 µg/kg but did result in durable tumor regression at 1,000 µg/kg. Data will be presented at the American Society of Hematology meeting in Atlanta in December. SGN-CD33A is a humanized mAb against CD33 conjugated to 2 pyrrolobenzodiazepine (PBD) dimer moieties. ...