Naratuximab emtansine (
IMGN529) is an investigational
antibody-drug conjugate consisting of a CD37-targeting antibody conjugated to the
maytansine-derived microtuble disruptor, DM1.
IMGN529 has shown promising preclinical and clinical activity in
non-Hodgkin lymphoma, including
diffuse large B-cell lymphoma (DLBCL). Due to the aggressive nature of the disease, DLBCL is often treated with combination
therapies to maximize clinical outcomes; therefore, we investigated the potential of combining
IMGN529 with both standard-of-care and emerging
therapies against multiple oncology-relevant targets and pathways. The strongest enhancement in potency was seen with anti-CD20
antibodies, including
rituximab. The combination of
IMGN529 and
rituximab was more potent than either agent alone, and this combinatorial benefit was associated with increased apoptotic induction and cell death. Additional studies revealed that
rituximab treatment increased the internalization and degradation of the CD37-targeting antibody moiety of
IMGN529. The combination of
IMGN529 and
rituximab was highly efficacious in multiple xenograft models, with superior antitumor efficacy seen compared to either agent alone or treatment with R-CHOP
therapy. These findings suggest a novel mechanism whereby the potency of
IMGN529 can be enhanced by CD20 binding, which results in the increased internalization and degradation of
IMGN529 leading to the generation of greater amounts of cytotoxic catabolite. Overall, these data provide a
biological rationale for the enhanced activity of
IMGN529 in combination with
rituximab and support the ongoing clinical evaluation of
IMGN529 in combination with
rituximab in patients with relapsed and/or refractory DLBCL.