Abstract
CD19 is ubiquitously expressed on chronic lymphocytic leukemia (CLL) cells and is therefore an attractive candidate for antibody targeting. XmAb5574 (aka MOR00208) is a novel humanized CD19 monoclonal antibody with an engineered Fc region to enhance Fc g receptor binding affinity. Here we report results of a first in human phase 1 trial of XmAb5574 in patients with relapsed or refractory CLL. Twenty-seven patients were enrolled to 6 escalating dose levels, with expansion at the highest dose level of 12 mg/kg. Nine doses of XmAb5574 were infused over 8 weeks. No maximal tolerated dose was reached, and the drug was generally well tolerated, with infusion reactions of grades 1 and 2 being the most common toxicities. Grade 3 and 4 toxicities occurred in 5 patients and included neutropenia, thrombocytopenia, increased aspartate aminotransferase, febrile neutropenia, and tumor lysis syndrome. XmAb5574 showed preliminary efficacy, with 18 patients (66.7%) responding by physical examination criteria and laboratory studies, and 8 patients (29.6%) responding by computed tomography criteria. Pharmacokinetics showeda half-life of 14 days with clearance that was not dose-dependent. In conclusion, this phase 1 trial demonstrates safety and preliminary efficacy of a novel Fc-engineered CD19 monoclonal antibody XmAb5574 and justifies movement into the phase 2 setting. This trial was registered at www.clinicaltrials.gov as #NCT01161511.
Original language | English (US) |
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Pages (from-to) | 3553-3560 |
Number of pages | 8 |
Journal | Blood |
Volume | 124 |
Issue number | 24 |
DOIs | |
State | Published - Dec 4 2014 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Immunology
- Hematology
- Cell Biology