Research

Chimeric antigen receptor (CAR) immunotherapy

Chimeric antigen receptor (CAR) immunotherapy is an innovative cancer treatment that uses a patient’s own immune cells to recognize and destroy cancer cells. CARs are synthetic receptors that combine the tumor-specific recognition of an antibody with the signaling machinery of a T cell, allowing precise targeting of cancer. Normally, immune defenses rely on the T cell receptor (TCR), which cancers can weaken or shut down to avoid detection. CAR technology bypasses these natural limitations by giving immune cells a new way to recognize tumors, allowing them to remain active even when the body’s usual immune responses are suppressed. We have developed an efficient, non-viral approach to generate T cells with redirected specificity by introducing CAR-encoding DNA plasmids using the Sleeping Beauty transposon system which has been successfully implemented in clinical trials at MD Anderson (INDs, 14193, 14577, 14739, 14739, IRB2011-0235).

Artificial antigen-presenting cells for cell therapy development

Efficient and reproducible activation of immune cells is essential for the generation of effective cell-based therapies, yet reliance on primary antigen-presenting cells introduces variability and limits scalability. To address this need, artificial antigen-presenting cells (AaPCs) provide a controlled platform for delivering defined activation and costimulatory signals ex vivo. We have therefore developed K562-derived AaPCs engineered to express selected costimulatory molecules, cytokines and target antigens, enabling robust and scalable expansion of T cells and natural killer (NK) cells. This system allows precise modulation of immune signaling to enhance immune cell function, persistence and antitumor activity.

Membrane bound cytokines for co-stimulation

Membrane-bound cytokines provide localized immune stimulation directly at the target site, enhancing therapeutic efficacy while minimizing systemic exposure and toxicity. A membrane-bound form of IL-21 (mIL-21) was developed by our group which, when co-expressed on K562-derived AaPC, has revolutionized the culturing protocol for ex vivo expansion of NK cells. This improved culturing technique has been successfully employed in clinical protocols involving NK cells by multiple investigators at MD Anderson (IRB protocols: 2011-0379, 2011-0493, 2012-0079, 2012-0708, 2012-0819). Similarly, membrane-bound IL-15 (mIL15) created in the lab has been demonstrated to enhance the generation of memory T cells, crucial for long-term immune surveillance after CAR or TCR T cell adoptive transfer. Additionally, our ongoing efforts involve adapting IL-15 expression on tumor-infiltrating lymphocytes (TILs) to improve their persistence following adoptive transfer, ultimately enhancing the effectiveness of this therapeutic approach.

Harnessing γδ T cells

Harnessing γδ T cells for cellular or targeted therapy holds considerable promise in the treatment of pediatric malignancies, as they possess a combination of innate and adaptive immune cell qualities — (i) they don’t recognize single antigens, (ii) they distribute and reside in abundance within tissues and (iii) they recognize target cells in an MHC-independent manner, and this low risk for alloreactivity allows for the development of allogeneic cell products. Due to limitation in expansion methods using zoledronic acid, we have adapted K562 derived AaPCs to provide activation and proliferation signals to ex vivo expand γδ T cells derived from (i) peripheral blood and (ii) umbilical cord blood.

Adoptive cell therapy using tumor-infiltrating lymphocytes

Adoptive cell therapy using tumor-infiltrating lymphocytes (TILs) has shown durable clinical responses in metastatic melanoma patients and is thus an attractive approach to treat other solid tumors. Discontinuation of anti-41BB antibody commercially along with high cost and variability of generating feeder cell layer for REP begs the need to develop a platform for the expansion of TILs to clinically meaningful numbers.  Therefore, our group has developed AaPCs from K562 cells, expressing desired T cell costimulatory molecules, as appealing “off-the-shelf” feeder cells for human application to expand TILs from solid tumor patient biopsies.

T cell receptors to target solid tumors

Solid tumors are often less responsive to CAR-based therapies, highlighting the need for alternative cell-based immunotherapeutic strategies. We have developed T cell receptors (TCRs) targeting the NY-ESO-1 antigen and demonstrated their efficacy in vitro and in vivo. Building on this work, we are expanding our efforts to identify tumor-specific neoantigens using next-generation sequencing and to discover TCRs targeting both neoantigens and oncogenic hotspot mutations across solid tumors.

Single cell analysis of CAR T cells

CAR T cell products used in clinical trials consist of heterogeneous cell populations with diverse functional and phenotypic properties. Although therapeutic efficacy depends on T cell persistence, current immunocorrelative studies largely focus on bulk phenotypic and functional analyses before infusion and limited characterization of cells recovered afterward. Therefore, to better understand the characteristics of CAR T cells at a single cell level, in collaboration with the Single Cell team of Navin Varadarajan, Ph.D., professor of Chemical and Molecular Engineering at the University of Houston, we have combined high-throughput time-lapse imaging microscopy in nanowell grids (TIMIG) with high-throughput image processing and multi-dimensional bioinformatics revealing different subset of CAR T cells. This information along with gene expression is shedding light on the potency of clinical-grade T cells.

Correlative studies for clinical trials

Understanding the therapeutic potential of infused T cells is important in predicting clinical response , patient management and in the development of improved adoptive cell therapies. Accordingly, the FDA advises observing subjects for delayed adverse events for as long as 15 years following exposure to the investigational gene therapy product. Therefore, our laboratory also performs correlative studies evaluating the characterization, functionality, presence and long-term persistence of infused CAR+ T cells in all our clinical trials using multi-parametric flow cytometry, PCR, multiplex gene expression using digital quantification of mRNA, deep sequencing and multiplex immunoassays for cytokine profiling.