Cellular Immunotherapy for B-Lineage Lymphoma Using Engineered CD19-Specific T-cells
Currently available therapeutics for relapsed/advanced B-cell lymphomas, such as diffuse large B-cell lymphoma (DLBCL), have limited curative potential and significant toxicities, particularly for the older patient population. Novel treatment modalities are needed, such as immunotherapy, which can combine enhanced anti-tumor efficacy with diminished toxicities through targeting of malignant B-cells.
The studies in Project 2 build upon City of Hope’s non-viral gene transfer methodologies for isolating and expanding genetically modified human T-cells. This has resulted in the design of a chimeric immunoreceptor that redirects the specificity of CD8+ cytotoxic T-lymphocytes (CTL’s) to CD19, a B-lineage cell-surface marker that is expressed on B-cell lymphomas. Although CD19-specific CD8+ T-cells can directly recognize and efficiently lyse lymphoma targets in vitro and in vivo, a variety of model systems and clinical adoptive immunotherapy trials have highlighted the importance of a CD4+ T-cell helper response for providing growth factors, such as IL-2, to support the persistence and expansion of CTL-effectors. To develop CD19-specific T-cells that are capable of sustaining an antigen-specific helper-response, we are developing and evaluating the ability of CD19-specific CD4+ T-cells to be activated for a TH1 response by CD19+ lymphoma cells. The full activation of CD4+ T-cells for IL-2 synthesis is dependent on signaling through both the T-cell receptor and co-stimulatory molecules.
Therefore, our second goal is to address the role of co-stimulation in general to achieve full-activation of CD19-specific helper T-cells. In particular, we will evaluate the ability of CD19-specific CD4+ T-cells to secrete IL-2 in response to CD28-costimulation mediated in cis and trans with binding of the CD19-specific chimeric immunoreceptor by CD19+ lymphoma. Our third objective is to model the anti-tumor activity of CD19-specific CD4+ T-cells in vivo by evaluating whether co-transfer of CD19-specific CD4+ T-cells can enhance the persistence and anti-tumor activity of CD19-specific CD8+ T-cells in NOD/scid mice bearing CD19+ lymphoma. A clinical trial employing the co-transfer of both CD19-specific CD8+ CTL’s and CD4+ TH1 help will require additional process development during the initial years of SPORE funding. Therefore, protocols will be developed to infuse T-cell products that have been thawed at the bedside, to incorporate high-capacity electroporation devices, perfusion bioreactors and washing/concentrating methods into closed fluid pathways, to eliminate serum from the T-cell culture media, and to use paramagnetic bead-selection to isolate desired T-cell populations.
We anticipate that these preclinical studies will form the basis of 2nd generation adoptive immunotherapy trial to evaluate the safety/feasibility/efficacy of combining CD4+ and CD8+ CD19-specific T-cells for advanced DLBCL.