Supriya Joshi

Abstract CD8 + T cells are critical mediators of antitumor immunity but differentiate into a dysfunctional state, known as T cell exhaustion, after persistent T cell receptor stimulation in the tumor microenvironment (TME). Exhausted T (T ex ) cells are characterized by upregulation of coinhibitory molecules and reduced polyfunctionality. T cells in the TME experience an immunosuppressive metabolic environment via reduced levels of nutrients and oxygen and a buildup of lactic acid. Here we show that terminally T ex cells uniquely upregulate Slc16a11 , which encodes monocarboxylate transporter 11 (MCT11). Conditional deletion of MCT11 in T cells reduced lactic acid uptake by T ex cells and improved their effector function. Targeting MCT11 with an antibody reduced lactate uptake specifically in T ex cells, which, when used therapeutically in tumor-bearing mice, resulted in reduced tumor growth. These data support a model in which T ex cells upregulate MCT11, rendering them sensitive to lactic acid present at high levels in the TME.

BACKGROUND: Cellular immunotherapies for cancer represent a means by which a patient's immune system can be augmented with high numbers of tumor-specific T cells. Chimeric antigen receptor (CAR) therapy involves genetic engineering to 'redirect' peripheral T cells to tumor targets, showing remarkable potency in blood cancers. However, due to several resistance mechanisms, CAR-T cell therapies remain ineffective in solid tumors. We and others have shown the tumor microenvironment harbors a distinct metabolic landscape that produces a barrier to immune cell function. Further, altered differentiation of T cells within tumors induces defects in mitochondrial biogenesis, resulting in severe cell-intrinsic metabolic deficiencies. While we and others have shown murine T cell receptor (TCR)-transgenic cells can be improved through enhanced mitochondrial biogenesis, we sought to determine whether human CAR-T cells could be enabled through a metabolic reprogramming approach. MATERIALS AND METHODS: and NT-PGC-1α constructs were used to co-transduce T cells with anti-EGFR CAR lentiviruses. We performed metabolic analysis via flow cytometry and Seahorse analysis in vitro as well as RNA sequencing. Finally, we treated therapeutically A549-carrying NSG mice with either PGC-1α or NT-PGC-1α anti-EGFR CAR-T cells. We also analyzed the differences in the tumor-infiltrating CAR-T cells when PGC-1α is co-expressed. RESULTS: Here, in this study, we show that an inhibition resistant, engineered version of PGC-1α, can metabolically reprogram human CAR-T cells. Transcriptomic profiling of PGC-1α-transduced CAR-T cells showed this approach effectively induced mitochondrial biogenesis, but also upregulated programs associated with effector functions. Treatment of immunodeficient animals bearing human solid tumors with these cells resulted in substantially improved in vivo efficacy. In contrast, a truncated version of PGC-1α, NT-PGC-1α, did not improve the in vivo outcomes. CONCLUSIONS: Our data further support a role for metabolic reprogramming in immunomodulatory treatments and highlight the utility of genes like PGC-1α as attractive candidates to include in cargo along with chimeric receptors or TCRs for cell therapy of solid tumors.

// Hussein F. Aqbi 1 , Liliya Tyutyunyk-Massey 2 , Rebecca C. Keim 1, 3 , Savannah E. Butler 1, 3 , Theresa Thekkudan 2 , Supriya Joshi 4 , Timothy M. Smith 1 , Dipankar Bandyopadhyay 3, 5 , Michael O. Idowu 3, 6 , Harry D. Bear 3, 7 , Kyle K. Payne 8 , David A. Gewirtz 2, 3 and Masoud H. Manjili 1, 3, 6, 9 1 Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 2 Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 3 Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 4 Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 5 Department of Biostatistics, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 6 Department of Pathology, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 7 Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA 8 Department of Immunology, Moffitt Cancer Center, Tampa, 33612, FL, USA 9 VCU Institute of Molecular Medicine, Virginia Commonwealth University School of Medicine, Richmond, 23298, VA, USA Correspondence to: David A. Gewirtz, email: david.gewirtz@vcuhealth.org Masoud H. Manjili, email: masoud.manjili@vcuhealth.org Keywords: breast cancer; autophagy; tumor dormancy; tumor escape and relapse; cancer immunotherapy Received: March 15, 2018      Accepted: April 07, 2018      Published: April 24, 2018 ABSTRACT Breast cancer patients who initially respond to cancer therapies often succumb to distant recurrence of the disease. It is not clear why people with the same type of breast cancer respond to treatments differently; some escape from dormancy and relapse earlier than others. In addition, some tumor clones respond to immunotherapy while others do not. We investigated how autophagy plays a role in accelerating or delaying recurrence of neu-overexpressing mouse mammary carcinoma (MMC) following adriamycin (ADR) treatment, and in affecting response to immunotherapy. We explored two strategies: 1) transient blockade of autophagy with chloroquine (CQ), which blocks fusion of autophagosomes and lysosomes during ADR treatment, and 2) permanent inhibition of autophagy by a stable knockdown of ATG5 (ATG5 KD ), which inhibits the formation of autophagosomes in MMC during and after ADR treatment. We found that while CQ prolonged tumor dormancy, but that stable knockdown of autophagy resulted in early escape from dormancy and recurrence. Interestingly, ATG5 KD MMC contained an increased frequency of ADR-induced polyploid-like cells and rendered MMC resistant to immunotherapy. On the other hand, a transient blockade of autophagy did not affect the sensitivity of MMC to immunotherapy. Our observations suggest that while chemotherapy-induced autophagy may facilitate tumor relapse, cell-intrinsic autophagy delays tumor relapse, in part, by inhibiting the formation of polyploid-like tumor dormancy.

The modeling of chimeric antigen receptor (CAR) T cell therapies has been mostly focused on immunodeficient models. However, there are many advantages in studying CAR-T cell biology in an immunocompetent setting. We generated a fully murine CAR targeting CD105 (endoglin), a component of the TGFβ receptor expressed on the surface of certain solid tumors and acute leukemias. CD105-targeted CAR-T cells can be grown from various murine backgrounds, tracked in vivo by congenic marks, and be activated by CD105 in isolation or expressed by tumor cells. CD105-targeted CAR-T cells were toxic at higher doses but proved safe in lower doses and modestly effective in treating wild-type B16 melanoma-bearing mice. CAR-T cells infiltrating the tumor expressed high levels of exhaustion markers and exhibited metabolic insufficiencies. We also generated a human CD105 CAR, which was efficacious in treating human melanoma and acute myeloid leukemia in vivo. Our work details a new murine model of CAR-T cell therapy that can be used from immunologists to further our understanding of CAR-T cell biology. We also set the foundation for further exploration of CD105 as a possible human CAR-T cell target.