Akt1 and -2 inhibition diminishes terminal differentiation and enhances central memory CD8+ T-cell proliferation and survival

Differential Proteins Expression Distinguished Between Patients With Infectious and Noninfectious Uveitis

PURPOSE

We investigated the aqueous humor proteome and associated plasma proteome in patients with infectious or noninfectious uveitis.

METHODS

AH and plasma were obtained from 28 patients with infectious uveitis (IU), 29 patients with noninfectious uveitis (NIU) and 35 healthy controls undergoing cataract surgery. The proteins profile was analyzed by SomaScan technology.

RESULTS

We found 1844 and 2484 proteins up-regulated and 124 and 161 proteins down-regulated in the AH from IU and NIU groups, respectively. In the plasma, three proteins were up-regulated in NIU patients, and one and five proteins were down-regulated in the IU and NIU patients, respectively. The results of pathway enrichment analysis for both IU and NIU groups were related mostly to inflammatory and regulatory processes.

CONCLUSION

SomaScan was able to detect novel AH and plasma protein biomarkers in IU and NIU patients. Also, the unique proteins found in both AH and plasma suggest a protein signature that could distinguish between infectious and noninfectious uveitis.

Parkin Deficiency Suppresses Antigen Presentation to Promote Tumor Immune Evasion and Immunotherapy Resistance

Parkin is an E3 ubiquitin ligase, which plays a key role in the development of Parkinson disease. Parkin defects also occur in numerous cancers, and a growing body of evidence indicates that Parkin functions as a tumor suppressor that impedes a number of cellular processes involved in tumorigenesis. Here, we generated murine and human models that closely mimic the advanced-stage tumors where Parkin deficiencies are found to provide deeper insights into the tumor suppressive functions of Parkin. Loss of Parkin expression led to aggressive tumor growth, which was associated with poor tumor antigen presentation and limited antitumor CD8+ T-cell infiltration and activation. The effect of Parkin deficiency on tumor growth was lost following depletion of CD8+ T cells. In line with previous findings, Parkin deficiency was linked with mitochondria-associated metabolic stress, PTEN degradation, and enhanced Akt activation. Increased Akt signaling led to dysregulation of antigen presentation, and treatment with the Akt inhibitor MK2206-2HCl restored antigen presentation in Parkin-deficient tumors. Analysis of data from patients with clear cell renal cell carcinoma indicated that Parkin expression was downregulated in tumors and that low expression correlated with reduced overall survival. Furthermore, low Parkin expression correlated with reduced patient response to immunotherapy. Overall, these results identify a role for Parkin deficiency in promoting tumor immune evasion that may explain the poor prognosis associated with loss of Parkin across multiple types of cancer.

SIGNIFICANCE

Parkin prevents immune evasion by regulating tumor antigen processing and presentation through the PTEN/Akt network, which has important implications for immunotherapy treatments in patients with Parkin-deficient tumors.

A systems and computational biology perspective on advancing CAR therapy

In the recent decades, chimeric antigen receptor (CAR) therapy signaled a new revolutionary approach to cancer treatment. This method seeks to engineer immune cells expressing an artificially designed receptor, which would endue those cells with the ability to recognize and eliminate tumor cells. While some CAR therapies received FDA approval and others are subject to clinical trials, many aspects of their workings remain elusive. Techniques of systems and computational biology have been frequently employed to explain the operating principles of CAR therapy and suggest further design improvements. In this review, we sought to provide a comprehensive account of those efforts. Specifically, we discuss various computational models of CAR therapy ranging in scale from organismal to molecular. Then, we describe the molecular and functional properties of costimulatory domains frequently incorporated in CAR structure. Finally, we describe the signaling cascades by which those costimulatory domains elicit cellular response against the target. We hope that this comprehensive summary of computational and experimental studies will further motivate the use of systems approaches in advancing CAR therapy.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

Exploring the Potential Mechanism of Qi-Shen-Di-Huang Drug Formulary for Myasthenia Gravis (MG) based on UHPLC-QE-MS Network Pharmacology and Molecular Docking Techniques

Myasthenia gravis (MG) is a rare and refractory autoimmune disease, and Qi Shen Di Huang (QSDH) drug formulary is an in-hospital herbal decoction with proven clinical efficacy in treating MG. Currently, most of the research on the QSDH drug formulary has concentrated on its clinical efficacy, and there is a lack of systematic study on the material basis. The active compounds and their mechanism of action have not been entirely determined. Therefore, this study sought to identify the active compounds in the QSDH drug formulary and analyze the key targets and potential mechanisms. We used ultra-performance liquid chromatography Q Exactive-mass spectrometry (UHPLC-QE-MS) and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database to identify and screen 85 active ingredients corresponding to 59 potential targets (17 herbs) associated with myasthenia gravis, and further identified AKT1 as the primary core target and the PI3K/AKT signaling pathway as the most substantial enriched pathway. Molecular docking and UPLC-MS analysis identified quercetin, luteolin, wogonin, kaempferol, laccasein, and epigallocatechin gallate are the core compounds of the QSDH drug formulary. In vivo rat studies showed that the QSDH drug formulary reduced Lennon's clinical score and decreased acetylcholine receptor antibody levels in peripheral blood rats with experimental autoimmune myasthenia gravis. In addition, the QSDH drug formulary downregulated P-PI3K/PI3K and P-Akt/Akt protein expression. Collectively, these findings describe the role and potential mechanism of the QSDH drug formulary in the treatment of MG, which exerts potential value by acting on AKT targets and regulating the PI3K/AKT signaling pathway and providing a theoretical reference for QSDH drug formulary application in the clinical treatment of MG.

Immune senescence in multiple myeloma-a role for mitochondrial dysfunction?

Age-related immune dysfunction is primarily mediated by immunosenescence which results in ineffective clearance of infective pathogens, poor vaccine responses and increased susceptibility to multi-morbidities. Immunosenescence-related immunometabolic abnormalities are associated with accelerated aging, an inflammatory immune response (inflammaging) and ultimately frailty syndromes. In addition, several conditions can accelerate the development of immunosenescence, including cancer. This is a bi-directional interaction since inflammaging may create a permissive environment for tumour development. Multiple myeloma (MM) is a mature B-cell malignancy that presents in the older population. MM exemplifies the interaction of age- (Host Response Biology; HRB) and disease-related immunological dysfunction, contributing to the development of a frailty syndrome which impairs the therapeutic impact of recent advances in treatment strategies. Understanding the mechanisms by which accelerated immunological aging is induced and the ways in which a tumour such as MM influences this process is key to overcoming therapeutic barriers. A link between cellular mitochondrial dysfunction and the acquisition of an abnormal immune phenotype has recently been described and has widespread physiological consequence beyond the impact on the immune system. Here we outline our current understanding of normal immune aging, describe the mechanism of immunometabolic dysfunction in accelerating this process, and propose the role these processes are playing in the pathogenesis of MM.

Akt isoforms in the immune system

Akt is a PI3K-activated serine-threonine kinase that exists in three distinct isoforms. Akt's expression in most immune cells, either at baseline or upon activation, reflects its importance in the immune system. While Akt is most highly expressed in innate immune cells, it plays crucial roles in both innate and adaptive immune cell development and/or effector functions. In this review, we explore what's known about the role of Akt in innate and adaptive immune cells. Wherever possible, we discuss the overlapping and distinct role of the three Akt isoforms, namely Akt1, Akt2, and Akt3, in immune cells.

A fluorogenic probe for granzyme B enables in-biopsy evaluation and screening of response to anticancer immunotherapies

Immunotherapy promotes the attack of cancer cells by the immune system; however, it is difficult to detect early responses before changes in tumor size occur. Here, we report the rational design of a fluorogenic peptide able to detect picomolar concentrations of active granzyme B as a biomarker of immune-mediated anticancer action. Through a series of chemical iterations and molecular dynamics simulations, we synthesize a library of FRET peptides and identify probe H5 with an optimal fit into granzyme B. We demonstrate that probe H5 enables the real-time detection of T cell-mediated anticancer activity in mouse tumors and in tumors from lung cancer patients. Furthermore, we show image-based phenotypic screens, which reveal that the AKT kinase inhibitor AZD5363 shows immune-mediated anticancer activity. The reactivity of probe H5 may enable the monitoring of early responses to anticancer treatments using tissue biopsies.

Anti-Gr-1 Antibody Provides Short-Term Depletion of MDSC in Lymphodepleted Mice with Active-Specific Melanoma Therapy

Lymphodepletion, reconstitution and active-specific tumor cell vaccination (LRAST) enhances the induction of tumor-specific T cells in a murine melanoma model. Myeloid-derived suppressor cells (MDSC) may counteract the induction of tumor-reactive T cells and their therapeutic efficacy. Thus, the aim of the study was to evaluate a possible benefit of MDSC depletion using anti-Gr-1 antibodies (Ab) in combination with LRAST. Female C57BL/6 mice with 3 days established subcutaneous (s.c.) D5 melanoma were lymphodepleted with cyclophosphamide and reconstituted with naive splenocytes. Vaccination was performed with irradiated syngeneic mGM-CSF-secreting D5G6 melanoma cells. MDSC depletion was performed using anti-Gr-1 Ab (clone RB6-8C5). Induction of tumor-specific T cells derived from tumor vaccine draining lymph nodes (TVDLN) was evaluated by the amount of tumor-specific interferon (IFN)-γ release. LRAST combined with anti-Gr-1 mAb administration enhanced the induction of tumor-specific T cells in TVDLN capable of releasing IFN-γ in a tumor-specific manner. Additional anti-Gr-1 mAb administration in LRAST-treated mice delayed growth of D5 melanomas by two weeks. Furthermore, we elucidate the impact of anti-Gr-1-depleting antibodies on the memory T cell compartment. Our data indicate that standard of care treatment regimens against cancer can be improved by implementing agents, e.g., depleting antibodies, which target and eliminate MDSC.

AKT Isoforms in the Immune Response in Cancer

AKT is a protein kinase that exists in three isoforms: AKT1, AKT2, and AKT3. Though similar in structure, these isoforms display different effects. AKT is activated downstream of PI3K, and together, this signaling pathway helps regulate cellular processes including cell growth, proliferation, metabolism, survival, and apoptosis. Disruption in these pathways has been associated with disorders including cardiovascular diseases, developmental disorders, inflammatory responses, autoimmune diseases, neurologic disorders, type 2 diabetes, and several cancers. In cancer, deregulation in the PI3K/AKT pathway can be manifested as tumorigenesis, pathological angiogenesis, and metastasis. Increased activity has been correlated with tumor progression and resistance to cancer treatments. Recent studies have suggested that inhibition of the PI3K/AKT pathway plays a significant role in the development, expansion, and proliferation of cells of the immune system. Additionally, AKT has been found to play an important role in differentiating regulatory T cells, activating B cells, and augmenting tumor immunosurveillance. This emphasizes AKT as a potential target for inhibition in cancer therapy. This chapter reviews AKT structure and regulation, its different isoforms, its role in immune cells, and its modulation in oncotherapy.

PI3K Isoforms in CD8+ T Cell Development and Function

CD8⁺ T cells are an essential part of the immune system and play a vital role in defending against tumors and infections. The phosphoinositide-3-kinase (PI3K), especially class I, is involved in numerous interrelated signaling pathways which control CD8⁺ T cell development, maturation, migration, activation, and differentiation. While CD8⁺ T lymphocytes express all class I PI3K isoforms (PI3Kα, PI3Kβ, PI3Kδ, and PI3Kγ), isoform-specific functions, especially for PI3Kα and PI3Kβ have not been fully elucidated. A few studies suggest the important role of p110δ and p110γ in CD8⁺ T cell activation, signaling, chemotaxis and function and several clinical trials are currently testing the effect of isoform-specific inhibitors in various types of cancers, including Indolent Non-Hodgkin Lymphoma, Peripheral T cell Lymphoma, Chronic Lymphocytic Leukemia, Small Lymphocytic Lymphoma, non-small cell lung carcinoma (NSCLC), head & neck cancer, and breast cancer. This chapter summarizes current knowledge of the roles of various PI3K isoforms and downstream signaling pathways in regulating CD8⁺ T cell fate, including cell proliferation, migration, and memory generation. We also discuss certain clinical trials employing PI3K inhibitors for cancer therapy, their limitations, and future perspectives.

Targeting the PI3K/Akt/mTOR pathway: A therapeutic strategy in COVID-19 patients

Some COVID-19 patients suffer complications from anti-viral immune responses which can lead to both a dangerous cytokine storm and development of blood-borne factors that render severe thrombotic events more likely. The precise immune response profile is likely, therefore, to determine and predict patient outcomes and also represents a target for intervention. Anti-viral T cell exhaustion in the early stages is associated with disease progression. Dysregulation of T cell functions, which precedes cytokine storm development and neutrophil expansion in alveolar tissues heralds damaging pathology.T cell function, cytokine production and factors that attract neutrophils to the lung can be modified through targeting molecules that can modulate T cell responses. Manipulating T cell responses by targeting the PI3K/Akt/mTOR pathway could provide the means to control the immune response in COVID-19 patients. During the initial anti-viral response, T cell effector function can be enhanced by delaying anti-viral exhaustion through inhibiting PI3K and Akt. Additionally, immune dysregulation can be addressed by enhancing immune suppressor functions by targeting downstream mTOR, an important intracellular modulator of cellular metabolism. Targeting this signalling pathway also has potential to prevent formation of thrombi due to its role in platelet activation. Furthermore, this signalling pathway is essential for SARS-cov-2 virus replication in host cells and its inhibition could, therefore, reduce viral load. The ultimate goal is to identify targets that can quickly control the immune response in COVID-19 patients to improve patient outcome. Targeting different levels of the PI3K/Akt/mTOR signalling pathway could potentially achieve this during each stage of the disease.

(-)-4-O-(4-O-β-D-glucopyranosylcaffeoyl) quinic acid enhanced the efficacy of anti-PD-L1 against esophageal carcinoma through inhibiting PI3K pathway

PURPOSE

Using antibodies to block the programmed cell death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway as an immunotherapy has achieved great success in the clinical treatment of various types of carcinoma. However, the efficacy is limited because of tumor-mediated immune immunosuppression and evasion. This study demonstrated that inhibiting the PI3K pathway with (-)-4-O-(4-O-β-D-glucopyranosylcaffeoyl) quinic acid (QA), a new compound from endophytic fungus Penicillium citrinum of Avicennia marina, enhanced the therapeutic efficacy of anti-PD-L1 antibody against esophageal tumors.

MATERIALS AND METHODS

mEC25 cells were injected into C57BL/6 mice to establish a syngeneic esophageal tumor model. Tumor infiltration lymphocytes (TILs) were analyzed by flow cytometry. Gene and protein expression was detected by qPCR and western blot, respectively. Moreover, the therapeutic effects of QA combining with anti-PD-L1 antibody were evaluated in the tumor model.

RESULTS

These data demonstrated that inhibition of PI3K with QA could overcome immunosuppression and promote the response of T-lymphocytes, resulting in the restoration of cytotoxic T cell-mediated tumor control. QA and anti-PD-L1 combination therapy significantly delayed tumor growth.

CONCLUSIONS

Our results provide a scientific basis to develop combination therapies involving anti-PD-L1 and PI3K inhibitors to improve responses in patients with esophageal cancer.

Enhancing T Cell Chemotaxis and Infiltration in Glioblastoma

Glioblastoma is an immunologically 'cold' tumor, which are characterized by absent or minimal numbers of tumor-infiltrating lymphocytes (TILs). For those tumors that have been invaded by lymphocytes, they are profoundly exhausted and ineffective. While many immunotherapy approaches seek to reinvigorate immune cells at the tumor, this requires TILs to be present. Therefore, to unleash the full potential of immunotherapy in glioblastoma, the trafficking of lymphocytes to the tumor is highly desirable. However, the process of T cell recruitment into the central nervous system (CNS) is tightly regulated. Naïve T cells may undergo an initial licensing process to enter the migratory phenotype necessary to enter the CNS. T cells then must express appropriate integrins and selectin ligands to interact with transmembrane proteins at the blood-brain barrier (BBB). Finally, they must interact with antigen-presenting cells and undergo further licensing to enter the parenchyma. These T cells must then navigate the tumor microenvironment, which is rich in immunosuppressive factors. Altered tumoral metabolism also interferes with T cell motility. In this review, we will describe these processes and their mediators, along with potential therapeutic approaches to enhance trafficking. We also discuss safety considerations for such approaches as well as potential counteragents.

PI3K inhibitors are finally coming of age

Overactive phosphoinositide 3-kinase (PI3K) in cancer and immune dysregulation has spurred extensive efforts to develop therapeutic PI3K inhibitors. Although progress has been hampered by issues such as poor drug tolerance and drug resistance, several PI3K inhibitors have now received regulatory approval - the PI3Kα isoform-selective inhibitor alpelisib for the treatment of breast cancer and inhibitors mainly aimed at the leukocyte-enriched PI3Kδ in B cell malignancies. In addition to targeting cancer cell-intrinsic PI3K activity, emerging evidence highlights the potential of PI3K inhibitors in cancer immunotherapy. This Review summarizes key discoveries that aid the clinical translation of PI3Kα and PI3Kδ inhibitors, highlighting lessons learnt and future opportunities.

PI3K/Akt Pathway: The Indestructible Role of a Vintage Target as a Support to the Most Recent Immunotherapeutic Approaches

Simple Summary

PI3K/Akt pathway has an impressive story as tumor marker. PI3K-dependent solid tumors have been studied for several years in order to inhibit the pathway at different levels along the signaling. Despite the highly satisfactory results obtained in vitro and in xenograft mouse tumor models, the use of PI3K/Akt inhibitors in clinical trials resulted in being not as efficient as expected. With the emerging role of the tumor microenvironment in the response to therapy and the awareness, increasing in recent years, of the necessity to army the immune system against the tumor, new opportunities have emerged for PI3K/Akt inhibitors. Here, we show that PI3K/Akt, in addition to its function as tumor marker, exerts a pivotal role as an immunomodulator. Recent studies demonstrate that PI3K/Akt pathway is crucial for the regulation of the immune system and that its inhibition in combination with immunomodulatory agents may provide a new therapeutic approach for cancer.

Abstract

Pathologic activation of PI3Ks and the subsequent deregulation of its downstream signaling pathway is among the most frequent events associated with cellular transformation, cancer, and metastasis. PI3Ks are also emerging as critical factors in regulating anti-tumor immunity by either promoting an immunosuppressive tumor microenvironment or by controlling the activity and the tumor infiltration of cells involved in the immune response. For these reasons, significant pharmaceutical efforts are dedicated to inhibiting the PI3K pathway, with the main goal to target the tumor and, at the same time, to enhance the anti-tumor immunity. Recent immunotherapeutic approaches involving the use of adoptive cell transfer of autologous genetically modified T cells or immune check-point inhibitors showed high efficacy. However, mechanisms of resistance to these kinds of therapy are emerging, due in part to the inhibition of effector T cell functions exerted by the immunosuppressive tumor microenvironment. Here, we first describe how inhibition of PI3K/Akt pathway contribute to enhance anti-tumor immunity and further discuss how inhibitors of the pathway are used in combination with different immunomodulatory and immunotherapeutic agents to improve anti-tumor efficacy.

Diverse Roles of Akt in T cells

Akt kinases translate various external cues into intracellular signals that control cell survival, proliferation, metabolism and differentiation. This review discusses the requirement for Akt and its targets in determining the fate and function of T cells. We discuss the importance of Akt at various stages of T cell development including β-selection during which Akt fulfills the energy requirements of highly proliferative DN3 cells. Akt also plays an integral role in CD8 T cell biology where its regulation of Foxo transcription factors and mTORC1 metabolic activity controls effector versus memory CD8 T cell differentiation. Finally, Akt promotes the differentiation of naïve CD4 T cells into Th1, Th17 and Tfh cells but inhibits the development of Treg cells. We also highlight how modulating Akt in T cells is a promising avenue for enhancing cell-based cancer immunotherapy.

Expression and Clinical Significance of KLRG1 and 2B4 on T Cells in the Peripheral Blood and Tumour of Patients with Cervical Cancer

Background: Killer cell lectin-like receptor G1 (KLRG1) and 2B4 play important roles in the immune regulation and immune tolerance to tumor cells by inhibiting T cell function. However, the clinical relevance of KLRG1 and 2B4 to cervical cancer remains to be understood.Methods: We measured the frequency of KLRG1+ or 2B4+ cells in CD4+ or CD8 + T cells derived from peripheral blood or tumour biopsies in cervical cancer patients by flow cytometry.Results: Compared with healthy controls, the level of KLRG1 and 2B4 on CD8 + T cells in the blood of the patients increased significantly (P = .0056 and .0441). KLRG1 level on CD8 + T cells and 2B4 level on CD4 + T cells in peripheral blood were significantly higher than in tumor tissues (P < .0001 and P = .0003). Higher KLRG1 level on blood-derived CD8 + T cells was observed in patients older than 54 years (P = .001) or tested to be HPV-negative (P = .026). Tumor-infiltrated CD8 + T cells demonstrated elevated KLRG1 level in patients having pelvic lymph node metastasis (P = .016). Increased 2B4 level on blood-derived CD8 + T cells was also observed in patients older than 54 years (P < .001). KLRG1 expression on both CD4 + T (P = .0158) and CD8 + T (P = .0187) cells in the peripheral blood increased after radiotherapy.Conclusion: KLRG1 level on T cells was related to age and HPV in patients with cervical cancer, while 2B4 level on T cells was related to age, underlying their roles in the host immune response to cervical cancer. Radiotherapy can improve the immune function of patients.

Cell composition and expansion strategy can reduce the beneficial effect of AKT-inhibition on functionality of CD8+ T cells

AKT-inhibition is a promising approach to improve T cell therapies; however, its effect on CD4⁺ T cells is insufficiently explored. Previously, we and others showed that AKT-inhibition during ex vivo CD8⁺ T cell expansion facilitates the generation of polyfunctional T cells with stem cell memory-like traits. However, most therapeutic T cell products are generated from lymphocytes, containing CD4⁺ T cells that can affect CD8⁺ T cells dependent on the Th-subset. Here, we investigated the effect of AKT-inhibition on CD4⁺ T cells, during separate as well as total T cell expansions. Interestingly, ex vivo AKT-inhibition preserved the early memory phenotype of CD4⁺ T cells based on higher CD62L, CXCR4 and CCR7 expression. However, in the presence of AKT-inhibition, Th-differentiation was skewed toward more Th2-associated at the expense of Th1-associated cells. Importantly, the favorable effect of AKT-inhibition on the functionality of CD8⁺ T cells drastically diminished in the presence of CD4⁺ T cells. Moreover, also the expansion method influenced the effect of AKT-inhibition on CD8⁺ T cells. These findings indicate that the effect of AKT-inhibition on CD8⁺ T cells is dependent on cell composition and expansion strategy, where presence of CD4⁺ T cells as well as polyclonal stimulation impede the favorable effect of AKT-inhibition.

S-15 in combination of Akt inhibitor promotes the expansion of CD45RA-CCR7+ tumor infiltrating lymphocytes with high cytotoxic potential and downregulating PD-1+Tim-3+ cells as well as regulatory T cells

Background

Autologous tumor-infiltrating lymphocytes (Tils) immunotherapy is a promising treatment in patients with advanced hepatocellular cancer. Although Tils treatment has shown great promise, their persistence and the efficacy after adoptive-transfer are insufficient and remain a challenge. Studies have demonstrated that IL-15 and Akt inhibitor can regulate T cell differentiation and memory. Here, we constructed S-15 (Super human IL-15), a fusion protein consisting of human IL-15, the sushi domain of the IL-15 receptor α chain and human IgG-Fc. Herein we compared the effects of S-15 with IL-2 or in combination with Akti on the expansion and activation of Tils.

Methods

Hepatocellular cancer tissues were obtained from 6 patients, Tils were expanded using IL-2, IL-2/S-15, IL-2/Akti or in combination IL-2/S-15/Akti. At day 10, anti-CD3 antibody was added to the culture media and expanded to day 25. The composition, exhaustion and T-cell differentiation markers (CD45RA/CCR7) were analyzed by flow cytometry.

Results

We found that IL-2/S-15/Akti expanded Tils and showed the highest percentage of central memory CD45RA^-CCR7⁺ phenotype prior to anti-CD3 antibody activation and after anti-CD3 antibody activation. T cells cultured with IL-2/S-15/Akti exhibited a mixture of CD4⁺, CD8⁺, and CD3⁺CD4^-CD8^- T cells; S-15 in combination with Akt inhibitor downregulated the expression of PD-1⁺Tim-3⁺ on Tils and decreased the Tregs in Tils. Additionally, the Tils expanded in the presence of the Akt inhibitor and S-15 showed enhanced antitumor activity as indicated by the increase in IFN-γ producing tumor infiltrating CD8⁺ T cells and without comprising the Tils expansion.

Conclusion

Our study elucidates that IL-2/S-15/Akti expanded Tils and represent a viable source for the cellular therapy for patients with hepatocellular cancer.

PD-1 blockade in subprimed CD8 cells induces dysfunctional PD-1+CD38hi cells and anti-PD-1 resistance

Understanding resistance to antibody to programmed cell death protein 1 (PD-1; anti-PD-1) is crucial for the development of reversal strategies. In anti-PD-1-resistant models, simultaneous anti-PD-1 and vaccine therapy reversed resistance, while PD-1 blockade before antigen priming abolished therapeutic outcomes. This was due to induction of dysfunctional PD-1⁺CD38^hi CD8⁺ cells by PD-1 blockade in suboptimally primed CD8 cell conditions induced by tumors. This results in erroneous T cell receptor signaling and unresponsiveness to antigenic restimulation. On the other hand, PD-1 blockade of optimally primed CD8 cells prevented the induction of dysfunctional CD8 cells, reversing resistance. Depleting PD-1⁺CD38^hi CD8⁺ cells enhanced therapeutic outcomes. Furthermore, non-responding patients showed more PD-1⁺CD38⁺CD8⁺ cells in tumor and blood than responders. In conclusion, the status of CD8⁺ T cell priming is a major contributor to anti-PD-1 therapeutic resistance. PD-1 blockade in unprimed or suboptimally primed CD8 cells induces resistance through the induction of PD-1⁺CD38^hi CD8⁺ cells that is reversed by optimal priming. PD-1⁺CD38^hi CD8⁺ cells serve as a predictive and therapeutic biomarker for anti-PD-1 treatment. Sequencing of anti-PD-1 and vaccine is crucial for successful therapy.

Comprehensive Characterization of a Next-Generation Antiviral T-Cell Product and Feasibility for Application in Immunosuppressed Transplant Patients

Viral infections have a major impact on morbidity and mortality of immunosuppressed solid organ transplant (SOT) patients because of missing or failure of adequate pharmacologic antiviral treatment. Adoptive antiviral T-cell therapy (AVTT), regenerating disturbed endogenous T-cell immunity, emerged as an attractive alternative approach to combat severe viral complications in immunocompromised patients. AVTT is successful in patients after hematopoietic stem cell transplantation where T-cell products (TCPs) are manufactured from healthy donors. In contrast, in the SOT setting TCPs are derived from/applied back to immunosuppressed patients. We and others demonstrated feasibility of TCP generation from SOT patients and first clinical proof-of-concept trials revealing promising data. However, the initial efficacy is frequently lost long-term, because of limited survival of transferred short-lived T-cells indicating a need for next-generation TCPs. Our recent data suggest that Rapamycin treatment during TCP manufacture, conferring partial inhibition of mTOR, might improve its composition. The aim of this study was to confirm these promising observations in a setting closer to clinical challenges and to deeply characterize the next-generation TCPs. Using cytomegalovirus (CMV) as model, our next-generation Rapamycin-treated (Rapa-)TCP showed consistently increased proportions of CD4⁺ T-cells as well as CD4⁺ and CD8⁺ central-memory T-cells (T_CM). In addition, Rapamycin sustained T-cell function despite withdrawal of Rapamycin, showed superior T-cell viability and resistance to apoptosis, stable metabolism upon activation, preferential expansion of T_CM, partial conversion of other memory T-cell subsets to T_CM and increased clonal diversity. On transcriptome level, we observed a gene expression profile denoting long-lived early memory T-cells with potent effector functions. Furthermore, we successfully applied the novel protocol for the generation of Rapa-TCPs to 19/19 SOT patients in a comparative study, irrespective of their history of CMV reactivation. Moreover, comparison of paired TCPs generated before/after transplantation did not reveal inferiority of the latter despite exposition to maintenance immunosuppression post-SOT. Our data imply that the Rapa-TCPs, exhibiting longevity and sustained T-cell memory, are a reasonable treatment option for SOT patients. Based on our success to manufacture Rapa-TCPs from SOT patients under maintenance immunosuppression, now, we seek ultimate clinical proof of efficacy in a clinical study.

PI3Kα/δ inhibition promotes anti-tumor immunity through direct enhancement of effector CD8+ T-cell activity

PI3K inhibitors with differential selectivity to distinct PI3K isoforms have been tested extensively in clinical trials, largely to target tumor epithelial cells. PI3K signaling also regulates the immune system and inhibition of PI3Kδ modulate the tumor immune microenvironment of pre-clinical mouse tumor models by relieving T-regs-mediated immunosuppression. PI3K inhibitors as a class and PI3Kδ specifically are associated with immune-related side effects. However, the impact of mixed PI3K inhibitors in tumor immunology is under-explored. Here we examine the differential effects of AZD8835, a dual PI3Kα/δ inhibitor, specifically on the tumor immune microenvironment using syngeneic models. Continuous suppression of PI3Kα/δ was not required for anti-tumor activity, as tumor growth inhibition was potentiated by an intermittent dosing/schedule in vivo. Moreover, PI3Kα/δ inhibition delivered strong single agent anti-tumor activity, which was associated with dynamic suppression of T-regs, improved CD8⁺ T-cell activation and memory in mouse syngeneic tumor models. Strikingly, AZD8835 promoted robust CD8⁺ T-cell activation dissociated from its effect on T-regs. This was associated with enhancing effector cell viability/function. Together these data reveal novel mechanisms by which PI3Kα/δ inhibitors interact with the immune system and validate the clinical compound AZD8835 as a novel immunoncology drug, independent of effects on tumor cells. These data support further clinical investigation of PI3K pathway inhibitors as immuno-oncology agents.

Reinforce the antitumor activity of CD8+ T cells via glutamine restriction

The antitumor activity of activated CD8+ T cells in the tumor microenvironment seems to be limited due to their being metabolically unfit. This metabolic unfitness is closely associated with T‐cell exhaustion and impairment of memory formation, which are barriers to successful antitumor adoptive immunotherapy. We therefore assessed the role of glutamine metabolism in the antitumor activity of CD8⁺ T cells using a tumor‐inoculated mouse model. The adoptive transfer of tumor‐specific CD8⁺ T cells cultured under glutamine‐restricted (dGln) conditions or CD8⁺ T cells treated with specific inhibitors of glutamine metabolism efficiently eliminated tumors and led to better survival of tumor‐inoculated mice than with cells cultured under control (Ctrl) conditions. The decreased expression of PD‐1 and increased Ki67 positivity among tumor‐infiltrating CD8⁺ T cells cultured under dGln conditions suggested that the inhibition of glutamine metabolism prevents CD8⁺ T‐cell exhaustion in vivo. Furthermore, the transferred CD8⁺ T cells cultured under dGln conditions expanded more efficiently against secondary OVA stimulation than did CD8⁺ T cells under Ctrl conditions. We found that the expression of a pro‐survival factor and memory T cell‐related transcription factors was significantly higher in CD8⁺ T cells cultured under dGln conditions than in those cultured under Ctrl conditions. Given these findings, our study uncovered an important role of glutamine metabolism in the antitumor activity of CD8⁺ T cells. The novel adoptive transfer of tumor‐specific CD8⁺ T cells cultured in glutamine‐restricted conditions may be a promising approach to improve the efficacy of cell‐based adoptive immunotherapy.

Ex vivo AKT-inhibition facilitates generation of polyfunctional stem cell memory-like CD8+ T cells for adoptive immunotherapy

Adoptive T cell therapy has shown clinical potential for patients with cancer, though effective treatment is dependent on longevity and potency of the exploited tumor-reactive T cells. Previously, we showed that ex vivo inhibition of AKT using the research compound Akt-inhibitor VIII retained differentiation and improved functionality of minor histocompatibility antigen (MiHA)-specific CD8⁺ T cells. Here, we compared a panel of clinically applicable AKT-inhibitors with an allosteric or adenosine triphosphate-competitive mode of action. We analyzed phenotype, functionality, metabolism and transcriptome of AKT-inhibited CD8⁺ T cells using different T cell activation models. Most inhibitors facilitated T cell expansion while preserving an early memory phenotype, reflected by maintenance of CD62L, CCR7 and CXCR4 expression. Moreover, transcriptome profiling revealed that AKT-inhibited CD8⁺ T cells clustered closely to naturally occurring stem cell-memory CD8⁺ T cells, while control T cells resembled effector-memory T cells. Interestingly, AKT-inhibited CD8⁺ T cells showed enrichment of hypoxia-associated genes, which was consistent with enhanced glycolytic function. Notably, AKT-inhibition during MiHA-specific CD8⁺ T cell priming uncoupled preservation of early memory differentiation from ex vivo expansion. Furthermore, AKT-inhibited MiHA-specific CD8⁺ T cells showed increased polyfunctionality with co-secretion of IFN-γ and IL-2 upon antigen recall. Together, these data demonstrate that AKT-inhibitors with different modality of action promote the ex vivo generation of stem cell memory-like CD8⁺ T cells with a unique metabolic profile and retained polyfunctionality. Akt-inhibitor VIII and GDC-0068 outperformed other inhibitors, and are therefore promising candidates for ex vivo generation of superior tumor-reactive T cells for adoptive immunotherapy in cancer patients.

Concurrent PD-1 Blockade Negates the Effects of OX40 Agonist Antibody in Combination Immunotherapy through Inducing T-cell Apoptosis

Combination therapies that depend on checkpoint inhibitor antibodies (Abs) such as for PD-1 or its ligand (PD-L1) together with immune stimulatory agonist Abs like anti-OX40 are being tested in the clinic to achieve improved antitumor effects. Here, we studied the potential therapeutic and immune effects of one such combination: Ab to PD-1 with agonist Ab to OX40/vaccine. We tested the antitumor effects of different treatment sequencing of this combination. We report that simultaneous addition of anti-PD-1 to anti-OX40 negated the antitumor effects of OX40 Ab. Antigen-specific CD8⁺ T-cell infiltration into the tumor was diminished, the resultant antitumor response weakened, and survival reduced. Although we observed an increase in IFNγ-producing E7-specifc CD8⁺ T cells in the spleens of mice treated with the combination of PD-1 blockade with anti-OX40/vaccine, these cells underwent apoptosis both in the periphery and the tumor. These results indicate that anti-PD-1 added at the initiation of therapy exhibits a detrimental effect on the positive outcome of anti-OX40 agonist Ab. These findings have important implications on the design of combination immunotherapy for cancer, demonstrating the need to test treatment combination and sequencing before moving to the clinic. Cancer Immunol Res; 5(9); 755-66. ©2017 AACR.

Inhibition of AKT signaling uncouples T cell differentiation from expansion for receptor-engineered adoptive immunotherapy

Adoptive immunotherapies using T cells genetically redirected with a chimeric antigen receptor (CAR) or T cell receptor (TCR) are entering mainstream clinical practice. Despite encouraging results, some patients do not respond to current therapies. In part, this phenomenon has been associated with infusion of reduced numbers of early memory T cells. Herein, we report that AKT signaling inhibition is compatible with CAR and TCR retroviral transduction of human T cells while promoting a CD62L-expressing central memory phenotype. Critically, this intervention did not compromise cell yield. Mechanistically, disruption of AKT signaling preserved MAPK activation and promoted the intranuclear localization of FOXO1, a transcriptional regulator of T cell memory. Consequently, AKT signaling inhibition synchronized the transcriptional profile for FOXO1-dependent target genes across multiple donors. Expression of an AKT-resistant FOXO1 mutant phenocopied the influence of AKT signaling inhibition, while addition of AKT signaling inhibition to T cells expressing mutant FOXO1 failed to further augment the frequency of CD62L-expressing cells. Finally, treatment of established B cell acute lymphoblastic leukemia was superior using anti-CD19 CAR-modified T cells transduced and expanded in the presence of an AKT inhibitor compared with conventionally grown T cells. Thus, inhibition of signaling along the PI3K/AKT axis represents a generalizable strategy to generate large numbers of receptor-modified T cells with an early memory phenotype and superior antitumor efficacy.

Expansion of tumor-infiltrating lymphocytes and their potential for application as adoptive cell transfer therapy in human breast cancer

Adoptive cell transfer (ACT) of ex vivo expanded tumor-infiltrating lymphocytes (TILs) has been successful in treating a considerable proportion of patients with metastatic melanoma. In addition, some patients with several other solid tumors were recently reported to have benefited clinically from such ACT. However, it remains unclear whether ACT using TILs is broadly applicable in breast cancer, the most common cancer in women. In this study, the utility of TILs as an ACT source in breast cancers was explored by deriving TILs from a large number of breast cancer samples and assessing their biological potentials. We successfully expanded TILs ex vivo under a standard TIL culture condition from over 100 breast cancer samples, including all breast cancer subtypes. We also found that the information about the percentage of TIL and presence of tertiary lymphoid structure in the tumor tissues could be useful for estimating the number of obtainable TILs after ex vivo culture. The ex vivo expanded TILs contained a considerable level of central memory phenotype T cells (about 20%), and a large proportion of TIL samples were reactive to autologous tumor cells in vitro. Furthermore, the in vitro tumor-reactive autologous TILs could also function in vivo in a xenograft mouse model implanted with the primary tumor tissue. Collectively, these results strongly indicate that ACT using ex vivo expanded autologous TILs is a feasible option in treating patients with breast cancer.

Enhanced Therapeutic Efficacy and Memory of Tumor-Specific CD8 T Cells by Ex Vivo PI3K-δ Inhibition

Inhibition of specific Akt isoforms in CD8⁺ T cells promotes favored differentiation into memory versus effector cells, the former of which are superior in mediating antitumor immunity. In this study, we investigated the role of upstream PI3K isoforms in CD8⁺ T-cell differentiation and assessed the potential use of PI3K isoform-specific inhibitors to favorably condition CD8⁺ T cells for adoptive cell therapy. The phenotype and proliferative ability of tumor antigen-specific CD8+ T cells was assessed in the presence of PI3K-α, -β, or -δ inhibitors. Inhibition of PI3K-δ, but not PI3K-α or PI3K-β, delayed terminal differentiation of CD8⁺ T cells and maintained the memory phenotype, thus enhancing their proliferative ability and survival while maintaining their cytokine and granzyme B production ability. This effect was preserved in vivo after ex vivo PI3K-δ inhibition in CD8⁺ T cells destined for adoptive transfer, enhancing their survival and also the antitumor therapeutic activity of a tumor-specific peptide vaccine. Our results outline a mechanism by which inhibitions of a single PI3K isoform can enhance the proliferative potential, function, and survival of CD8⁺ T cells, with potential clinical implications for adoptive cell transfer and vaccine-based immunotherapies. Cancer Res; 77(15); 4135-45. ©2017 AACR.

β-catenin and PI3Kδ inhibition expands precursor Th17 cells with heightened stemness and antitumor activity

ICOS costimulation generates Th17 cells with durable memory responses to tumor. Herein, we found that ICOS induces PI3K/p110δ/Akt and Wnt/β-catenin pathways in Th17 cells. Coinhibiting PI3Kδ and β-catenin altered the biological fate of Th17 cells. Th17 cells inhibited of both pathways expressed less RORγt, which, in turn, reduced their ability to secrete IL-17. Unexpectedly, these cells were more effective (than uninhibited cells) at regressing tumor when infused into mice, leading to long-term curative responses. PI3Kδ inhibition expanded precursor Th17 cells with a central memory phenotype that expressed nominal regulatory properties (low FoxP3), while β-catenin inhibition enhanced Th17 multifunctionality in vivo. Remarkably, upon TCR restimulation, RORγt and IL-17 rebounded in Th17 cells treated with PI3Kδ and β-catenin inhibitors. Moreover, these cells regained β-catenin, Tcf7, and Akt expression, licensing them to secrete heightened IL-2, persist, and eradicate solid tumors without help from endogenous NK and CD8 T cells. This finding shines a light on ways to repurpose FDA-approved drugs to augment T cell-based cancer immunotherapies.

Targeting PI3K in Cancer: Impact on Tumor Cells, Their Protective Stroma, Angiogenesis, and Immunotherapy

The PI3K pathway is hyperactivated in most cancers, yet the capacity of PI3K inhibitors to induce tumor cell death is limited. The efficacy of PI3K inhibition can also derive from interference with the cancer cells' ability to respond to stromal signals, as illustrated by the approved PI3Kδ inhibitor idelalisib in B-cell malignancies. Inhibition of the leukocyte-enriched PI3Kδ or PI3Kγ may unleash antitumor T-cell responses by inhibiting regulatory T cells and immune-suppressive myeloid cells. Moreover, tumor angiogenesis may be targeted by PI3K inhibitors to enhance cancer therapy. Future work should therefore also explore the effects of PI3K inhibitors on the tumor stroma, in addition to their cancer cell-intrinsic impact.

SIGNIFICANCE

The PI3K pathway extends beyond the direct regulation of cancer cell proliferation and survival. In B-cell malignancies, targeting PI3K purges the tumor cells from their protective microenvironment. Moreover, we propose that PI3K isoform-selective inhibitors may be exploited in the context of cancer immunotherapy and by targeting angiogenesis to improve drug and immune cell delivery. Cancer Discov; 6(10); 1090-105. ©2016 AACR.

Old-School Chemotherapy in Immunotherapeutic Combination in Cancer, A Low-cost Drug Repurposed

Cancer immunotherapy has proven to be a potent treatment modality. Although often successful in generating antitumor immune responses, cancer immunotherapy is frequently hindered by tumor immune-escape mechanisms. Among immunosuppressive strategies within the tumor microenvironment, suppressive immune regulatory cells play a key role in promoting tumor progression through inhibiting the effector arm of the immune response. Targeting these suppressive cells can greatly enhance antitumor immune therapies, hence augmenting a highly effective therapeutic antitumor response. Several approaches are being tested to enhance the effector arm of the immune system while simultaneously inhibiting the suppressor arm. Some of these approaches are none other than traditional drugs repurposed as immune modulators. Cyclophosphamide, an old-school chemotherapeutic agent used across a wide range of malignancies, was found to be a potent immune modulator that targets suppressive regulatory immune cells within the tumor microenvironment while enhancing effector cells. Preclinical and clinical findings have confirmed the ability of low doses of cyclophosphamide to selectively deplete regulatory T cells while enhancing effector and memory cytotoxic T cells within the tumor microenvironment. These immune effects translate to suppressed tumor growth and enhanced survival, evidence of antitumor therapeutic efficacy. This article discusses the reincarnation of cyclophosphamide as an immune modulator that augments novel immunotherapeutic approaches. Cancer Immunol Res; 4(5); 377-82. ©2016 AACR.

Mutant KRAS Conversion of Conventional T Cells into Regulatory T Cells

Constitutive activation of the KRAS oncogene in human malignancies is associated with aggressive tumor growth and poor prognosis. Similar to other oncogenes, KRAS acts in a cell-intrinsic manner to affect tumor growth or survival. However, we describe here a different, cell-extrinsic mechanism through which mutant KRAS contributes to tumor development. Tumor cells carrying mutated KRAS induced highly suppressive T cells, and silencing KRAS reversed this effect. Overexpression of the mutant KRAS(G12V)gene in wild-type KRAS tumor cells led to regulatory T-cell (Treg) induction. We also demonstrate that mutant KRAS induces the secretion of IL10 and transforming growth factor-β1 (both required for Treg induction) by tumor cells through the activation of the MEK-ERK-AP1 pathway. Finally, we report that inhibition of KRAS reduces the infiltration of Tregs in KRAS-driven lung tumorigenesis even before tumor formation. This cell-extrinsic mechanism allows tumor cells harboring a mutant KRAS oncogene to escape immune recognition. Thus, an oncogene can promote tumor progression independent of its transforming activity by increasing the number and function of Tregs. This has a significant clinical potential, in which targeting KRAS and its downstream signaling pathways could be used as powerful immune modulators in cancer immunotherapy.

Polyfunctional Melan-A-specific tumor-reactive CD8(+) T cells elicited by dacarbazine treatment before peptide-vaccination depends on AKT activation sustained by ICOS

The identification of activation pathways linked to antitumor T-cell polyfunctionality in long surviving patients is of great relevance in the new era of immunotherapy. We have recently reported that dacarbazine (DTIC) injected one day before peptide-vaccination plus IFN-α improves the antitumor lytic activity and enlarges the repertoire of Melan-A-specific T-cell clones, as compared with vaccination alone, impacting the overall survival of melanoma patients. To identify the mechanisms responsible for this improvement of the immune response, we have analyzed the endogenous and treatment-induced antigen (Ag)-specific response in a panel of Melan-A-specific CD8⁺ T-cell clones in terms of differentiation phenotype, inhibitory receptor profile, polyfunctionality and AKT activation. Here, we show that Melan-A-specific CD8⁺ T cells isolated from patients treated with chemoimmunotherapy possess a late differentiated phenotype as defined by the absence of CD28 and CD27 co-stimulatory molecules and high levels of LAG-3, TIM-3 and PD-1 inhibitory receptors. Nevertheless, they show higher proliferative potential and an improved antitumor polyfunctional effector profile in terms of co-production of TNF-α, IFNγ and Granzyme-B (GrB) compared with cells derived from patients treated with vaccination alone. Polyfunctionality is dependent on an active AKT signaling related to the engagement of the co-stimulatory molecule ICOS. We suggest that this phenotypic and functional signature is dictated by a fine-tuned balance between TCR triggering, AKT activation, co-stimulatory and inhibitory signals induced by chemoimmunotherapy and may be associated with antitumor T cells able to protect patients from tumor recurrence.

Targeting CD8 T-Cell Metabolism in Transplantation

Infiltration of effector CD8 T cells plays a major role in allograft rejection, and increases in memory and terminally differentiated effector memory CD8 T cells are associated with long-term allograft dysfunction. Alternatively, CD8 regulatory T cells suppress the inflammatory responses of effector lymphocytes and induce allograft tolerance in animal models. Recently, there has been a renewed interest in the field of immunometabolics and its important role in CD8 function and differentiation. The purpose of this review is to highlight the key metabolic pathways involved in CD8 T cells and to discuss how manipulating these metabolic pathways could lead to new immunosuppressive strategies for the transplantation field.