TRU-016, under development by Trubion Pharmaceuticals Inc and Facet Biotech Corp, is an intravenously administered anti-CD37 IgG fusion protein for the potential treatment of B-cell malignancies, including chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL), as well as for autoimmune and inflammatory diseases. TRU-016 was created by humanizing SMIP-016, a mouse/human chimeric protein that demonstrated antitumor activity against lymphoid malignancies in preclinical studies, including in human B-cell tumor mouse xenograft models. In addition, TRU-016 demonstrated synergistic or additive activity in NHL cells in combination with rituximab, rapamycin, doxorubicin and bendamustine. In a phase I/II clinical trial in refractory or relapsed patients with CLL or small lymphocytic lymphoma, TRU-016 was well tolerated, with clinical benefit and a reduced absolute lymphocyte count observed in all cohorts dosed at> 0.1 mg/kg. TRU-016 is a promising therapeutic agent for patients with B-cell lymphoid malignancies, especially patients refractory to standard treatment.