L2 In vivo live imaging of human T/B cell lymphoma cross-linking mediated by bispecific CD20-TCB antibody (2020)

<h3>Introduction</h3> Cancer Immune Therapies have shown unprecedented results in improving tumor control.<sup>1–3</sup> However, many patients are still refractory to treatment. A deeper understanding of the mode of action of the different CITs sub-classes may help improving therapeutic approaches to reach better anti-tumor response. For this reason, we developed a multi-photon intra-vital microscopy (MP-IVM) approach to study <i>in vivo,</i> at single cell level, the tumor microenvironment upon treatment with CD20-targeting T-cell bispecific antibodies (TCB) [4] in a preclinical model of diffuse large B cell lymphomas (DLBCL). <h3>Methods</h3> To selectively monitor clinical lead molecules in the context of human T cell responses, we developed a skinfold chamber model [5] in last generation humanized mice [6] that allows visualization, by MP-IVM, of labelled human T cells co-injected intra-dermally with WSU-DLCL2, a human DLBCL. We have used this model to investigate T cells recruitment to tumors upon CD20-TCB therapy: by intra-venously injecting labeled T cells in mice treated with selected blocking antibodies, we were able to identify dedicated pathways induced by CD20-TCB and regulating T cell influx into the tumor bed. Furthermore, we developed a user-independent quantification platform to assess changes in the dynamics of T cell motility and time of interaction with tumor cells. <h3>Results/Discussion</h3> We have developed an experimental preclinical model that aims to reduce xenoreaction (human T cell reaction against mouse tissue) by utilizing T cells derived from humanized mice, educated within murine thymus. We demonstrate that such model is optimal to quantify human T cell dynamics <i>in vivo</i>. We show that CD20-TCB localizes in the tumor and acts on tumor-resident T cell motility within 1 hour post i.v. injection (defined as functional PK), causing a sharp reduction in their speed (from 4 to 2 µm/min) and an increase in tumor/T cell interaction time; those changes last up to 72h post-treatment. In addition, we prove how the initial tumor/T cell interaction mediated by CD20-TCB lead to peripheral T cells recruitment into the tumor. This mechanism is dependent on the presence of tumor-resident T cells and on IFNg-CXCL10 pathway. Inhibiting any of these two parameters resulted in reduced T cells infiltration from the periphery and reduced anti-tumor efficacy. <h3>Conclusion</h3> We developed a reliable imaging and analysis pipeline to investigate <i>in vivo</i> T cell dynamics and recruitment and applied it to the study of CD20-TCB treatment of DLBCL model. Our approach has shed new lights into the MoA of this new class of immune-therapeutics, demonstrating that the IFNγ-CXCL10 pathway is involved in T cell recruitment upon CD20-TCB treatment. <h3>Disclosure Information</h3> <b>F. Cremasco:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>E. Menietti:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>D. Speziale:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>J. Sam:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>S. Sammicheli:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>S. Chen:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>M. Richard:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>C. Klein:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>P. Umana:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>M. Bacac:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>S. Colombetti:</b> A. Employment (full or part-time); Significant; Roche Glycart AG. <b>M. Perro:</b> A. Employment (full or part-time); Significant; Roche Glycart AG.