Data from Novel BAFF-Receptor Antibody to Natively Folded Recombinant Protein Eliminates Drug-Resistant Human B-cell Malignancies <i>In Vivo</i>

Abstract

<div>Abstract<p><b>Purpose:</b> mAbs such as anti-CD20 rituximab are proven therapies in B-cell malignancies, yet many patients develop resistance. Novel therapies against alternative targets are needed to circumvent resistance mechanisms. We sought to generate mAbs against human B-cell–activating factor receptor (BAFF-R/TNFRSF13C), which has not yet been targeted successfully for cancer therapy.</p><p><b>Experimental Design:</b> Novel mAbs were generated against BAFF-R, expressed as a natively folded cell surface immunogen on mouse fibroblast cells. Chimeric BAFF-R mAbs were developed and assessed for <i>in vitro</i> and <i>in vivo</i> monotherapy cytotoxicity. The chimeric mAbs were tested against human B-cell tumor lines, primary patient samples, and drug-resistant tumors.</p><p><b>Results:</b> Chimeric antibodies bound with high affinity to multiple human malignant B-cell lines and induced potent antibody-dependent cellular cytotoxicity (ADCC) against multiple subtypes of human lymphoma and leukemia, including primary tumors from patients who had relapsed after anti-CD20 therapy. Chimeric antibodies also induced ADCC against ibrutinib-resistant and rituximab-insensitive CD20-deficient variant lymphomas, respectively. Importantly, they demonstrated remarkable <i>in vivo</i> growth inhibition of drug-resistant tumor models in immunodeficient mice.</p><p><b>Conclusions:</b> Our method generated novel anti–BAFF-R antibody therapeutics with remarkable single-agent antitumor effects. We propose that these antibodies represent an effective new strategy for targeting and treating drug-resistant B-cell malignancies and warrant further development. <i>Clin Cancer Res; 24(5); 1114–23. ©2017 AACR</i>.</p></div>