Development of Chimeric Antigen Receptors Targeting Multiple Myeloma

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An important focus of my work is development of chimeric antigen receptor T cell therapies for multiple myeloma, which is a usually incurable malignancy of plasma cells. Anti-BCMA CARs: My group was the first to design and construct CARs that specifically recognize B-cell maturation antigen (BCMA). BCMA has a very restricted expression pattern in normal tissues, but BCMA is expressed on the malignant plasma cells of multiple myeloma. The BCMA specific CARs that we have constructed specifically recognize multiple myeloma cell lines and primary myeloma cells in vitro and eradicate myeloma tumors in mice. An extensive analysis of BCMA expression in normal human tissues by immunohistochemistry and quantitative PCR has been conducted. Except for expression by normal plasma cells, BCMA expression was not detected in nomal human organs by immunohistochemistry. A clinical trial of anti-BCMA-CAR-transduced T cells for treating advanced multiple myeloma has been opened for enrollment since September, 2014. So far 23 patients have been treated. There have been impressive responses on this trial, which were the first demonstrated examples of elimination of measurable multiple myeloma by CAR T cells. This work led to a publication in the journal Blood in 2016. In conjunction with Bluebird Bio, Inc. We have developed a new anti-BCMA CAR that Bluebird licensed from the NCI. This new CAR was developed in part in my laboratory. This new CAR is being tested in a multicenter trial of which I participate as a site PI.. The NCI is a leading enrollment site for this trial. The trial is showing promising results with most patients treated obtaining objective anti-myeloma responses. This trial was most recently reported at the American Society of Clinical Oncology meeting in June, 2017. Another general area of research on CAR T-cell therapies for multiple myeloma is improving the design of CARs. We have a project looking at how changes in the structure of the hinge region of CARs can be quite important in determining in vivo efficacy of CARs. We have shown that very small changes in the hinge region of anti-BCMA CAR T cells can affect the in vivo function of CAR T cells. We are currently working on designing novel fully-human antigen-recognition domains for anti-BCMA CAR T cells. We are also designing CARs against antigens other than BCMA because multiple myeloma is a phenotypically heterogeneous malignancy in many cases, so targeting more than one antigen might be necessary to effectively induce long progression-free intervals of multiple myeloma.