Research progress and design optimization of CAR-T therapy for pancreatic ductal adenocarcinoma

BCL6 overexpression in CD4+ T cells induces Tfh-like transdifferentiation and enhances antitumor efficiency of CAR-T therapy in pancreatic cancer

PDAC is a typical "cold tumor" characterized by low immune cell infiltration and a suppressive immune microenvironment. We previously observed the existence of a rare group of follicular helper T cells (Tfh) that could enhance antitumor immune responses by recruiting other immune cells in PDAC. In this study, we ectopically expressed BCL6 in CD4+ T cells, and successfully induced Tfh-like transdifferentiation in vitro. This strategy provided abundant Tfh-like cells (iTfhs) that can recruit CD8+ T cells like endogenous Tfhs. Subsequently, Chimeric Antigen Receptors (CARs) against both MSL (Mesothelin) and EPHA2 (Ephrin receptor A2) were used to modify iTfh cells, and the CAR-iTfh cells significantly improved infiltration and antitumor cytotoxicity of co-cultured CD8+ T cells. After that, combinatory administration of CAR-iTfh & CAR-CD8 T cell therapy displayed a better effect in repressing the PDAC tumors in xenograft mouse models, compared to conventional CAR-CD4 & CAR-CD8 combinations, and the models received the CAR-iTfh & CAR-CD8 T cells displayed a significantly improved survival rate. Our study revealed the plasticity of Thelper differentiation, expanded the source of Tfh-like cells for cell therapy, and demonstrated a novel and potentially more efficient cellular composition for CAR-T therapy.

Enhancement of Tumorigenicity, Spheroid Niche, and Drug Resistance of Pancreatic Cancer Cells in Three-Dimensional Culture System

The three-dimensional (3D) cell culture technique has been applied comprehensively as a variable platform for medical research, biochemical signal pathway analysis, and evaluation of anti-tumor treatment response due to an excellent recapitulation of a tumor microenvironment (TME) in the in vitro cultured cancer cells. Pancreatic cancer (PaC) is one of the toughest malignancies with a complex TME and refractory treatment response. To comprehensively study the TME of PaC, there is an eager need to develop a 3D culture model to decompose the cellular components and their cross interactions. Herein, we establish a 3D PaC culture system with cancer stem cell (CSC) and scalability properties. To validate our model, we tested the individual PaC cell and the combined effects with cancer-associated fibroblasts (CAFs) on cancer tumorigenicity, the cellular interaction through the CXCR3/CXCL10 axis, and cellular responses reflection of anti-cancer treatments. With the help of our 3D technology, a simulated malignant spheroid with important stromal populations and TME physiochemical properties may be successfully recreated. It can be used in a wide range of preclinical research and helpful in advancing basic and translational cancer biology.

Effect of chimeric antigen receptor T cells against protease-activated receptor 1 for treating pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a 5-year survival rate of 6% following a diagnosis, and novel therapeutic modalities are needed. Protease-activated receptor 1 (PAR1) is abundantly overexpressed by both tumor cells and multiple stroma cell subsets in the tumor microenvironment (TME), thereby offering a suitable immunotherapy target.

METHODS

A chimeric antigen receptor (CAR) strategy was applied to target PAR1 using a human anti-PAR1 scFv antibody fused to the transmembrane region with two co-stimulatory intracellular signaling domains of cluster of differentiation 28 (CD28) and CD137 (4-1BB), added to CD3ζ in tandem.

RESULTS

The engineered PAR1CAR-T cells eliminated PAR1 overexpression and transforming growth factor (TGF)-β-mediated PAR1-upregulated cancer cells by approximately 80% in vitro. The adoptive transfer of PAR1CAR-T cells was persistently enhanced and induced the specific regression of established MIA PaCa-2 cancer cells by > 80% in xenograft models. Accordingly, proinflammatory cytokines/chemokines increased in CAR-T-cell-treated mouse sera, whereas Ki67 expression in tumors decreased. Furthermore, the targeted elimination of PAR1-expressing tumors reduced matrix metalloproteinase 1 (MMP1) levels, suggesting that the blocking of the PAR1/MMP1 pathway constitutes a new therapeutic option for PDAC treatment.

CONCLUSIONS

Third-generation PAR1CAR-T cells have antitumor activity in the TME, providing innovative CAR-T-cell immunotherapy against PDAC.

GAS6-based CAR-T cells exhibit potent antitumor activity against pancreatic cancer

BACKGROUND

The receptor tyrosine kinases TAM family (TYRO3, AXL, and MERTK) are highly expressed in multiple forms of cancer cells and tumor-associated macrophages and promote the development of cancers including pancreatic tumor. Targeting TAM receptors could be a promising therapeutic option.

METHODS

We designed a novel CAR based on the extracellular domain of growth arrest-specific protein 6 (GAS6), a natural ligand for all TAM members. The ability of CAR-T to kill pancreatic cancer cells is tested in vitro and in vivo, and the safety is evaluated in mice and nonhuman primate.

RESULTS

GAS6-CAR-T cells efficiently kill TAM-positive pancreatic cancer cell lines, gemcitabine-resistant cancer cells, and cancer stem-like cells in vitro. GAS6-CAR-T cells also significantly suppressed the growth of PANC1 xenografts and patient-derived xenografts in mice. Furthermore, these CAR-T cells did not induce obvious side effects in nonhuman primate or mice although the CAR was demonstrated to recognize mouse TAM.

CONCLUSIONS

Our findings indicate that GAS6-CAR-T-cell therapy may be effective for pancreatic cancers with low toxicity.

Establishment of a New Cryopreservation Solution for Chimeric Antigen Receptor T Cells

Preservation and transportation are essential for the clinical application of chimeric antigen receptor T (CAR-T) cells. This study aimed to optimize a cryopreservation solution for CAR-T cells and evaluate the antitumor efficiency of CAR-T cells using this optimized solution in vitro and in vivo. First, the stability of the cryopreservation solution for CAR-T infusion was detected by the L27 (3⁷) orthogonal experiment. Subsequently, osmolality and pH were analyzed for the preservation reagent. Additionally, apoptosis and CAR expression of CAR-T cells were measured by flow cytometry, and the cytotoxicity was determined by calcein-AM staining. The results showed that cryopreservation solutions used in this study demonstrated high chemical stability, which induced only 2% CAR-T cells apoptosis in optimal solutions, which were slightly lower than other commercial solutions. Moreover, the CAR expression was not significantly affected by preservation with these solutions. There were no significant differences in the cytotoxicity between fresh and thawed CAR-T cells cryopreserved in the cryopreservation solutions in vivo and in vitro. This study developed a new cryopreservation solution for CAR-T cells, and it was safe and also had negligible effects on the CAR-T cells antitumor activity.

Emerging agents for metastatic pancreatic cancer: spotlight on early phase clinical trials

INTRODUCTION

Despite the recent development of new chemotherapeutic regimens and combination strategies, metastatic pancreatic cancer (mPC) still shows only a modest response to conventional cytotoxic agents. However, several novel therapeutic agents targeting the unique features of mPC are showing promise in clinical trials.

AREA COVERED

This article reviews the current state of development of new agents targeting various systems and molecular pathways. We searched PubMed and clinicaltrials.gov in September 2021 with a special focus on ongoing early phase clinical trials to identify the promising therapeutic strategies for mPC.

EXPERT OPINION

Extensive tumor heterogeneity, complex tumor microenvironment, genetic alterations of the oncogenic signaling pathways, metabolic dysregulation, and a low immunogenicity are hurdles for current treatment approaches. Ongoing research efforts strive to overcome these hurdles and are showing some promising early results.

Coagulation Signaling through PAR1 as a Therapeutic Target in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal disease with a 5-year survival rate of less than 10% following diagnosis. The aggressive and invasive properties of pancreatic cancer tumors coupled with poor diagnostic options contribute to the high mortality rate since most patients present with late-stage disease. Accordingly, PDAC is linked to the highest rate of cancer-associated venous thromboembolic disease of all solid tumor malignancies. However, in addition to promoting clot formation, recent studies suggest that the coagulation system in PDAC mediates a reciprocal relationship, whereby coagulation proteases and receptors promote PDAC tumor progression and dissemination. Here, upregulation of tissue factor (TF) by tumor cells can drive local generation of the central coagulation protease thrombin that promotes cell signaling activity through protease-activated receptors (PARs) expressed by both tumor cells and multiple stromal cell subsets. Moreover, the TF-thrombin-PAR1 signaling axis appears to be a major mechanism of cancer progression in general and PDAC in particular. Here, we summarize the current literature regarding the role of PAR1 in PDAC and review possibilities for pharmacologically targeting PAR1 as a PDAC therapeutic approach.

Role of targeted immunotherapy for pancreatic ductal adenocarcinoma (PDAC) treatment: An overview

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid tumors with a high mortality rate and poor survival rate. Depending on the tumor stage, PDAC is either treated by resection surgery, chemotherapies, or radiotherapies. Various chemotherapeutic agents have been used to treat PDAC, alone or in combination. Despite the combinations, chemotherapy exhibits many side-effects leading to an increase in the toxicity profile amongst the PDAC patients. Additionally, these standard chemotherapeutic agents have only a modest impact on patient survival due to their limited efficacy. PDAC was previously considered as an immunologically silent malignancy, but recent findings have demonstrated that effective immune-mediated tumor cell death can be used for its treatment. PDAC is characterized by an immunosuppressive tumor microenvironment accompanied by the major expression of myeloid-derived suppressor cells (MDSC) and M2 tumor-associated macrophages. In contrast, the expression of CD8⁺ T cells is significantly low. Additionally, infiltration of mast cells in PDAC correlates with the poor prognosis. Immunotherapeutic agents target the immunity mediators and empower them to suppress the tumor and effectively treat PDAC. Different targets are studied and exploited to induce an antitumor immune response in PDAC patients. In recent times, site-specific delivery of immunotherapeutics also gained attention among researchers to effectively treat PDAC. In the present review, existing immunotherapies for PDAC treatment along with their limitations are addressed in detail. The review also includes the pathophysiology, traditional strategies and significance of targeted immunotherapies to combat PDAC effectively. Separately, the identification of ideal targets for the targeted therapy of PDAC is also reviewed exhaustively. Additionally, the review also addresses the applications of targeted immunotherapeutics like checkpoint inhibitors, adoptive T-cell therapy etc.

Dilemma and Challenge of Immunotherapy for Pancreatic Cancer

Pancreatic cancer is a tumor with a high degree of malignancy, morbidity, and mortality. Immunotherapy is another important treatment for pancreatic cancer in addition to surgery and chemotherapy, but its application in pancreatic cancer is very limited, which is related to the unique biological behavior of pancreatic cancer and the tumor microenvironment. The immunosuppressive microenvironment of pancreatic cancer is highly heterogeneous and presents challenges for immunotherapy. The transformation of tumor immunosuppressive microenvironment contributes to the response to tumor immunotherapy, such that the tumor undergoes functional reprogramming to change from immunologically "cold" to immunologically "hot." In this review, we summarized the research and progress in immunotherapy for pancreatic cancer, including immune checkpoint inhibitors, vaccines, adoptive T cell therapy, oncolytic viruses, and immunomodulators, and suggest that individualized, combination, and precise therapy should be the main direction of future immunotherapy in pancreatic cancer.

The Achilles' Heel of Pancreatic Cancer: Targeting pancreatic cancer's unique immunologic characteristics and metabolic dependencies in clinical trials

Abstract

Pancreatic ductal adenocarcinoma (PDAC) has a high mortality rate and is notoriously refractory to multiple cancer treatments. In recent years, cancer therapy has expanded beyond traditional cytotoxic chemotherapy to targeted agents and immunotherapy which have been successfully implemented in many cancers. Despite robust pre-clinical research, these novel therapies have only had a small impact on PDAC. However, there have been successes with emerging clinical data supporting a potential role for checkpoint inhibitor therapy and targeted therapy with poly (ADP-ribose) polymerase inhibitors for select subsets of PDAC patients. In this clinical review, we discuss recent pre-clinical evidence for targeting metabolic pathways as well as prevalent intratumoral immune subsets, and focus on clinical trials designed to test novel agents in PDAC. The challenge of translating pre-clinical findings to patients remains substantial and many clinical trials yield negative results, but collaborative efforts and renewed focus on novel clinical trials have led to optimism that we will identify additional options for PDAC patients and change outcomes for this deadly disease.

Research progress and design optimization of CAR-T therapy for pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant cancer with limited treatment options. Chimeric antigen receptor T cells (CAR-T) are genetically engineered T cells that can specifically kill tumor cells without major histocompatibility complex restriction. Encouraging progress in CAR-T therapy for PDAC has been made in preclinical and early phase clinical trials. Challenges in CAR-T therapy for solid tumors still exist, including immunosuppressive microenvironment, interstitial barrier, poor chemotaxis, and the "on-target, off-tumor" effect. Applying neoantigens of PDAC as targets for CAR-T therapy, recognizing the CAR-T subgroup with better antitumor effect, and designing a CAR-T system targeting stroma of PDAC may contribute to develop a powerful CAR-T therapy for PDAC in the future.