Peripheral Blood T-Cell Fitness Is Diminished in Patients With Pancreatic Carcinoma but Can Be Improved With Homeostatic Cytokines

The challenge of making the right choice: patient avatars in the era of cancer immunotherapies

Immunotherapies are a key therapeutic strategy to fight cancer. Diverse approaches are used to activate tumor-directed immunity and to overcome tumor immune escape. The dynamic interplay between tumor cells and their tumor(immune)microenvironment (T(I)ME) poses a major challenge to create appropriate model systems. However, those model systems are needed to gain novel insights into tumor (immune) biology and a prerequisite to accurately develop and test immunotherapeutic approaches which can be successfully translated into clinical application. Several model systems have been established and advanced into so-called patient avatars to mimic the patient´s tumor biology. All models have their advantages but also disadvantages underscoring the necessity to pay attention in defining the rationale and requirements for which the patient avatar will be used. Here, we briefly outline the current state of tumor model systems used for tumor (immune)biological analysis as well as evaluation of immunotherapeutic agents. Finally, we provide a recommendation for further development to make patient avatars a complementary tool for testing and predicting immunotherapeutic strategies for personalization of tumor therapies.

Tumor Microenvironment in Pancreatic Cancer Pathogenesis and Therapeutic Resistance

Pancreatic ductal adenocarcinoma (PDAC) features a prominent stromal microenvironment with remarkable cellular and spatial heterogeneity that meaningfully impacts disease biology and treatment resistance. Recent advances in tissue imaging capabilities, single-cell analytics, and disease modeling have shed light on organizing principles that shape the stromal complexity of PDAC tumors. These insights into the functional and spatial dependencies that coordinate cancer cell biology and the relationships that exist between cells and extracellular matrix components present in tumors are expected to unveil therapeutic vulnerabilities. We review recent advances in the field and discuss current understandings of mechanisms by which the tumor microenvironment shapes PDAC pathogenesis and therapy resistance.

Cleaved CDCP1 marks the spot: a neoepitope for RAS-driven cancers

A challenge in cancer treatment is targeting cancer cells while sparing normal cells. Thus, identifying cancer-specific neoepitopes is an active research area. Neoepitopes are generated by the accumulation of mutations; however, deadly cancer types, including pancreatic cancer, have a low mutational burden and, consequently, a paucity of neoantigens. In this issue of the JCI, Lim, Zhou, and colleagues describe a neoepitope generated upon proteolytic cleavage of the transmembrane CUB domain containing protein 1 (CDCP1). CDCP1 is overexpressed in cancer and portends a worse prognosis; previous attempts to target CDCP1 reduced cancer growth, but adversely affected the host. Here, the authors generated an antibody that specifically targeted cleaved CDCP1 (c-CDCP1) and developed a drug conjugate, a vector for radioactive ions, and a mediator of T cell activation. The therapeutics inhibited pancreatic cancer cell growth in vitro and in vivo. Exploiting proteolytic cleavage-derived neoantigens opens an attractive way for specifically targeting cancer cells.

The biological underpinnings of therapeutic resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related mortality in the United States and has only recently achieved a 5-yr survival rate of 10%. This dismal prognosis reflects the remarkable capacity of PDAC to effectively adapt to and resist therapeutic intervention. In this review, we discuss recent advances in our understanding of the biological underpinnings of PDAC and their implications as targetable vulnerabilities in this highly lethal disease.

Immunotherapy for pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a lethal cancer with an urgent need for better medical therapies. Efforts have been made to investigate the efficacy of immunotherapy, particularly given the hallmarks of immune suppression and exhaustion in PDAC tumors. Here, we review the molecular components responsible for the immune-privileged state in PDAC and provide an overview of the immunotherapeutic strategies for PDAC including vaccine therapy, checkpoint blockade, myeloid-targeted therapy, and immune agonist therapy.

Multimodal Mapping of the Tumor and Peripheral Blood Immune Landscape in Human Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is characterized by an immune-suppressive tumor microenvironment that renders it largely refractory to immunotherapy. We implemented a multimodal analysis approach to elucidate the immune landscape in PDA. Using a combination of CyTOF, single-cell RNA sequencing, and multiplex immunohistochemistry on patient tumors, matched blood, and non-malignant samples, we uncovered a complex network of immune-suppressive cellular interactions. These experiments revealed heterogeneous expression of immune checkpoint receptors in individual patient's T cells and increased markers of CD8+ T cell dysfunction in advanced disease stage. Tumor-infiltrating CD8+ T cells had an increased proportion of cells expressing an exhausted expression profile that included upregulation of the immune checkpoint TIGIT, a finding that we validated at the protein level. Our findings point to a profound alteration of the immune landscape of tumors, and to patient-specific immune changes that should be taken into account as combination immunotherapy becomes available for pancreatic cancer.

Dual Targeting of Mesothelin and CD19 with Chimeric Antigen Receptor-Modified T Cells in Patients with Metastatic Pancreatic Cancer

B cells infiltrate pancreatic ductal adenocarcinoma (PDAC) and in preclinical cancer models, can suppress T cell immunosurveillance in cancer. Here, we conducted a pilot study to assess the safety and feasibility of administering lentiviral-transduced chimeric antigen receptor (CAR)-modified autologous T cells redirected against mesothelin to target tumor cells along with CART cells redirected against CD19 to deplete B cells. Both CARs contained 4-1BB and CD3ζ signaling domains. Three patients with chemotherapy-refractory PDAC received 1.5 g/m² cyclophosphamide prior to separate infusions of lentiviral-transduced T cells engineered to express chimeric anti-mesothelin immunoreceptor SS1 (CART-Meso, 3 × 10⁷/m²) and chimeric anti-CD19 immunoreceptor (CART-19, 3 × 10⁷/m²). Treatment was well tolerated without dose-limiting toxicities. Best response was stable disease (1 of 3 patients). CART-19 (compared to CART-Meso) cells showed the greatest expansion in the blood, although persistence was transient. B cells were successfully depleted in all subjects, became undetectable by 7-10 days post-infusion, and remained undetectable for at least 28 days. Together, concomitant delivery of CART-Meso and CART-19 cells in patients with PDAC is safe. CART-19 cells deplete normal B cells but at the dose tested in these 3 subjects did not improve CART-Meso cell persistence.

The interplay between innate and adaptive immunity in cancer shapes the productivity of cancer immunosurveillance

The immune system is a vital determinant of cancer and shapes its trajectory. Notably, the immune reaction to cancer harbors dual potential for suppressing or promoting cancer development and progression. This polarity of the immune response is determined, in part, by the character of the interplay between innate and adaptive immunity. On the one hand, the innate immune compartment is a necessary proponent of cancer immunity by supporting an immunostimulatory state that enables T cell immunosurveillance. However, in the setting of cancer, innate immune cells are commonly polarized with immune-suppressive properties and as a result, orchestrate a tolerogenic niche that interferes with the cytotoxic potential of tumor antigen-specific T cells. Here, we discuss the role of innate immunity as a positive and negative regulator of adaptive immunosurveillance; moreover, we highlight how tumor cells may skew leukocytes toward an immunosuppressive state and, as such, subvert the phenotypic plasticity of the immune compartment to advance disease progression. These observations establish the precedent for novel therapeutic strategies that aim to restore the tumor microenvironment to an immunoreactive state and, in doing so, condition and maintain the immunogenicity of tumors to yield deep and durable responses to immunotherapy.