Project 1: Immunotherapy of B cell lymphoma with NKT cells

PROJECT SUMMARY / ABSTRACT Despite remarkable progress achieved with chimeric antigen receptor (CAR)-expressing T cells in the treatment of relapsed/refractory B lineage neoplasms, CD19-specific CAR (CAR.CD19) autologous T cell products are not curative for more than half of B-NHL patients. The long-term goal of Project 1 is to develop a safe and effective immunotherapy for B-NHL using both the natural and engineered properties of CD1d-restricted Va24-invariant natural killer T cells (NKTs). Unlike polyclonal T cells, NKTs have natural antilymphoma activity via direct cytotoxicity against CD1d+ lymphoblasts or/and by activation of other immune effectors; further, allogeneic NKTs do not produce graft-versus-host disease (GvHD) and can be prepared as “off-the-shelf” products. During the current project period, we have initiated a first-in-human phase I clinical trial of allo-CAR.CD19 NKTs (NCT03774654) and have treated the first four patients. The therapy was well tolerated and produced objective responses in three patients. However short persistence of CAR.CD19 NKTs in patient peripheral blood may decrease durability of response. To protect the therapeutic NKTs from host-mediated rejection, we have developed new CAR constructs that co-express artificial micro(mi)RNA (amiR), consisting of promoterless miRNA frames with embedded shRNA sequences targeting B2M and the class II major histocompatibility complex transactivator (CIITA). These CAR/amiR constructs produce a graded downregulation of HLA class-I and class-II in CAR-NKTs making them resistant to allogenic T and NK cells. We have also found that CAR-NKT therapeutic potency can be augmented by pharmacologic or transgenic regulation of LEF1 transcriptional activity, which controls NKT cell functional fitness. We hypothesize that allo-CAR.CD19 NKTs will continue to be well tolerated and effective against B-NHL; their therapeutic potency can be further increased via amiR-mediated protection from immune rejection and via LEF1-mediated retention of their antitumor activity. The following three specific aims will test our hypotheses: 1) to determine the safety, efficacy, and immunological activity of allo- CAR.CD19 NKTs in B-NHL patients; 2) to produce cGMP allo-NKTs co-expressing CAR.CD19 with B2M and CIITA amiRs and to determine the safety, efficacy, and immunological activity of allo-CAR.CD19/amiR NKTs in B-NHL patients; 3) to evaluate the mechanism by which LEF1 controls NKT cell functional fitness and test the therapeutic potency of NKTs co-expressing CAR.CD19 and LEF1 in pre-clinical B cell lymphoma models. The ongoing and proposed studies are the first to rigorously evaluate the utility of NKTs as a novel cellular platform for redirected “off-the-self” immunotherapy. If proven to be safe and effective, this approach will provide a foundation for a cost-effective cell therapy platform for B-NHL and perhaps other types of cancer as well.