Janssen R&D Lower Gwynedd Township/Spring House, PA, United States
Disclosure information not submitted.
Timothy Burwell1, Jeffrey Hall1, Suzanne Cole2, Sarah Tursi1, Isabelle Baribaud3, Kyle Bednar1, Naresh Kumar1, Julie Carman1, Navin Rao2 and Edith Janssen2, 1Janssen Research and Development, LLC, Spring House, PA, 2Janssen Research & Development, LLC, Spring House, PA, 3IGM Biosciences, Inc., Doylestown, PA
Background/Purpose: B cells contribute to the development and progression of autoimmune diseases through multiple mechanisms. Consequently, modulating B cell activation, B cell effector function, and plasmablast development holds great therapeutic potential. CD22 (Siglec-2) is an inhibitory receptor selectively expressed on B cells and has been shown to inhibit BCR downstream signaling. Here we tether CD22 to the B cell receptor (BCR) with a CD22 x CD79b bispecific Ab (bsAb) to potently inhibit B cell activation, proliferation, cytokine production, Ig production, and plasmablast accumulation.
Methods: Binding of the bsAb to different B cells was analyzed by flow cytometry using directly conjugated-bsAb. Potential for in vitro antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) was assessed in PBMC cultures in the presence of fresh serum. Impact on BCR downstream signaling upon IgM cross-linking was determined by phospho-flow of p-Syk and p-PLCg in purified B cells. PBMC and B cells were used to assess inhibitory capacity of the bsAb on B cell activation, proliferation, and cytokine production upon IgM cross-linking. PBMC from 15 RA patients and 17 matched healthy donors (HD) were used to verify inhibitory potential in rheumatologic disease.
For in vivo pharmacology studies, CD34+ reconstituted NSG mice were dosed as indicated, and serum IgM, frequency and composition of B cells and plasmablasts (spleen, blood), and splenic B cells functionality upon IgM cross-linking were assessed at indicated time points.
Results: Our CD22xCD79b bsAb showed strong, selective binding to all CD22 expressing B cell subsets without in vitro depletion. The bsAb potently inhibited the phosphorylation of BCR downstream signaling molecules Syk and PLCg upon IgM cross-linking, which correlated with significant reductions in B cell proliferation and cytokine production. Moreover, our bsAb potently inhibited the activation of B cells in PBMC from both HD and RA patients (CD69, CD83, CD86).
In vivo treatment of CD34+NSG mice with the bsAb showed a potent, dose-dependent reduction in serum IgM levels, concomitant with profound reductions of plasmablasts in the blood and spleen. In addition, splenic B cells from treated animals showed a significant dose-dependent reduction in their capacity to produce proinflammatory cytokines upon IgM cross-linking in vitro (IL-6, IL-8, CCL3, CCL4, CCL22).
Conclusion: Together this data shows that our CD22xCD79b bsAb is a potent inhibitor of B cell activation in vitro and in vivo, making it a promising approach for the treatment of autoimmune diseases with a pathogenic B cell component.
This work was supported by Janssen R&D, LLC
T. Burwell: Janssen, 3; J. Hall: Janssen, 3; S. Cole: Janssen, 3; S. Tursi: Janssen, 3; I. Baribaud: Janssen, 3; K. Bednar: Janssen, 3, 11; N. Kumar: Janssen, 3; J. Carman: Janssen, 3, 11; N. Rao: Janssen, 3, 11; E. Janssen: Janssen, 2, 11.
