Chimeric antigen receptor (CAR) T cell therapy, a form of genetically engineered immune cell therapy, is among the most effective treatments against cancers arising from immune B cells. For instance, patients relapsing from B cell acute lymphoblastic leukemia have a median survival of about 7 months. Following CAR-T therapy, over 60% are alive at 3 years post-treatment. Likewise, patients whose B cell lymphomas become resistant to chemotherapy usually succumb to the disease in ~6 months. If the same group is infused with CAR T cells on the other hand, over 40% are still alive at 5 years post-treatment. Despite this promise, translating these successes to other blood and solid tumors has not ...

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Chimeric antigen receptor (CAR) T cell therapy, a form of genetically engineered immune cell therapy, is among the most effective treatments against cancers arising from immune B cells. For instance, patients relapsing from B cell acute lymphoblastic leukemia have a median survival of about 7 months. Following CAR-T therapy, over 60% are alive at 3 years post-treatment. Likewise, patients whose B cell lymphomas become resistant to chemotherapy usually succumb to the disease in ~6 months. If the same group is infused with CAR T cells on the other hand, over 40% are still alive at 5 years post-treatment. Despite this promise, translating these successes to other blood and solid tumors has not been possible so far. This proposal seeks to solve this major drawback. CARs are built by fusing two proteins. An extracellular (antibody) domain that binds to tumor cell surface proteins, and an intracellular domain that directs the T cell to destroy the tumor. An ideal CAR should recognize tumor cells but not healthy tissue. In practice however selective targeting of the tumor is rarely feasible. For instance, the most common CAR T cell treatment against B cell lymphomas targets CD19, a surface protein that is present in essentially all B cells. Therefore, any anti-CD19 immunotherapy effectively destroys not only the lymphoma but also kills the normal B cells. While depleting the B cell compartment is clinically tolerable in patients, that is not the case for other immune cells (e.g. T cells) or indispensable organs (e.g., lung). Therefore, whereas there is little doubt that CAR T cells could be engineered to target most cancers, one key challenge is to identify safe targets specific for each tumor type so that the therapy delivers anti-cancer benefits while minimizing damage to normal tissues. A second reason why CAR T cells are not implemented more widely is because of the impenetrability of tumors, particularly solid tumors. That is because most cancers protect themselves with a thick net of proteins and sugars known as the extracellular matrix, which impedes infiltration of immune cells including the infused CAR T cells that can destroy them. A third challenge is that manufacturing CAR T cells is technically difficult. That is because the T cells used to produce the therapy are harvested from the patients themselves, who have invariably received several rounds of chemotherapy and/or radiation, treatments that compromise the quality and quantity of their T cells. The need to manufacture the CAR T cells on demand for each patient also increases their cost. To overcome these challenges, we have created a 'Consortium for Immune Cell Engineering' from two Texas institutions: MD Anderson Cancer Center (MDACC) and the University of Houston. The Consortium brings together three basic, translational and clinical scientists as well as recognized experts on a variety of cancers and immunotherapies to transition basic laboratory discoveries to the clinic. The three Principal Investigators are: Dr. Sattva Neelapu, the head of the Consortium and the principal investigator of Project 1 and the Administrative Core. He is a renowned Medical Oncologist and physician scientist at MDACC with expertise in clinical and translational research, the development of novel CAR T cell therapies, and the treatment of lymphoid malignancies. Dr. Rafael Casellas is the head of Project 2. He is a Molecular Immunologist also at MDACC who has extensive expertise in B cell biology and the production of single chain antibodies or Nanobodies for therapeutic use. Dr. Navin Varadarajan is the head of Project 3 and the Technical Core. He is an Immunoengineer at the Cullen College of Engineering at the University of Houston with a track record of developing innovative molecular and cellular technologies for immunotherapy. These three PIs will work together with several co-investigators including Drs. Anil Sood (a Gynecologic Oncologist and physician scientist with expertise in ovarian cancer models), Jeffrey Molldrem (a physician scientist with expertise in the generation of antibody-based therapeutics against HLA-peptide complexes and their translation into the clinic), Funda Meric-Bernstam (a physician scientist and surgeon with expertise in breast cancer models), Linghua Wang (a computational biologist with expertise in genomics and immuno-informatics), Ryan Sun (a biostatistician with expertise in novel statistical methodology), and Francisco Vega (a hematopathologist and physician scientist with expertise in lymphoid malignancies and related mouse models). The project PIs and co-investigators have a track record of working together and have generated preliminary data jointly for this proposal. They have more than 20 joint peer-reviewed publications, and at least five joint peer-reviewed grants that were previously funded. In Project 1, the investigators will evaluate a novel CAR T product in patients to destroy leukemias and lymphomas originating from T cells or NK cells by targeting a receptor known as CD94, which is highly expressed in T/NK cancers but only expressed in a subset of those normal cell types. To date, there are no successful therapies for these kinds of tumors. One risk of CAR T cell therapies, recently highlighted by the FDA, is the remote but real possibility that the DNA changes inflicted on T cells upon insertion of the CAR can lead to their transformation into tumors over time. To avoid this, the Consortium will study and implement a novel safety switch which, in case of toxicity or transformation, can rapidly destroy CAR T cells by using FDA-approved treatments. In addition, in Project 1, the Consortium will tackle the manufacturing problem of CAR T cell therapies. As aforementioned, T cells isolated from patients are often times not robust enough to induce tumor cell killing for extended periods of times following insertion of the synthetic CAR in the laboratory and their infusion back into the patients. An alternative strategy that has been explored for some time is the harvesting of T cells from healthy donors. However, this approach faces challenges on its own. Because donors are never fully compatible with the patients' immune system their T cells are either rejected and/or they attack healthy tissues in patients which they recognize as foreign. To avoid these outcomes, both the donor and the patients' cells must become invisible to each other. The Consortium will achieve this by depleting the donor T cells of key proteins that they use to recognize foreign tissues (the T cell receptor) or that the host immune system uses to recognize them in turn as foreign (major histocompatibility-peptide complexes). In Project 2, we will address the lack of cancer-specific proteins which makes it difficult to destroy non-B cell tumors without impacting healthy tissues. To this end, we will develop a new class of CARs using human single chain Nanobodies. These "NanoCARs" will recognize tumor intracellular proteins which are presented on their cell surface as bits and pieces by specialized proteins known as major histocompatibility complexes (MHCs). Because intracellular proteins are considerably more abundant than cell surface receptors (the traditional targets of CAR T cells) the likelihood of finding targets unique to each cancer is far improved. Using this novel approach, we will develop CARs to kill ovarian, uterine and triple negative breast cancers. In Project 3, we will tackle the impenetrability of solid tumors. We will do this by engineering CAR T cells to overexpress matrix metalloproteinase 8 (MMP8), an enzyme that degrades many of the components of tumor extracellular matrices. In preliminary studies, the Varadarajan group have shown MMP8 enhances the trafficking of CAR T cells into ovarian cancer tumors both in a petri dish and in mice. Without the support of their protective wall, we anticipate solid tumors will become sensitive to CAR T cell mediated killing. To ensure the cohesion of the three projects the Consortium will make use of an Administrative Core and a Functional Immunology and Bioinformatics (FIB) Core. The Administrative core will interface with CPRIT to ensure administrative and financial oversight, and work with an external advisory board to ensure timely progress of the grant objectives. Furthermore, the core will oversee the call for proposals and selection of related Pilot Projects from junior faculty at the two institutions as well as other institutions within the Gulf Coast Consortia that is composed of eight institutions in the Houston-Galveston area to enhance the objective of the proposal and provide training and mentorship to other investigators. The FIB core will make available a variety of cutting-edge technologies to monitor at a single-cell level the activity of CAR T cells and their interaction with tumor cells during the immunotherapy in culture, in mouse models, and in patients. In summary, we anticipate that this proposal will overcome the current limitations of CAR T cell therapies and will have a major impact on cancer treatment. It could lead to the development of three CAR T products against multiple cancers including T/NK-cell malignancies, high-grade serous ovarian cancer, triple-negative breast cancer, and uterine cancer. The interdepartmental and interinstitutional interactions between basic and translational researchers and clinical investigators with disease-specific expertise is expected to facilitate rapid clinical translation of the therapeutic products, which could also lead to future commercialization opportunities. Collectively, these combined efforts are likely to serve as a catalyst to develop highly effective CAR T cell therapy products for many hematological and solid malignancies in the future. It also creates an ideal environment for mentorship of next generation researchers interested in therapeutic discovery and development.

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