Increase of Tumor Infiltrating γδ T-cells in Pancreatic Ductal Adenocarcinoma Through Remodeling of the Extracellular Matrix by a Hyaluronan Synthesis Suppressor, 4-Methylumbelliferone

Nano-Drug Delivery Systems Targeting CAFs: A Promising Treatment for Pancreatic Cancer

Currently, pancreatic cancer (PC) is one of the most lethal malignant tumors. PC is typically diagnosed at a late stage, exhibits a poor response to conventional treatment, and has a bleak prognosis. Unfortunately, PC's survival rate has not significantly improved since the 1960s. Cancer-associated fibroblasts (CAFs) are a key component of the pancreatic tumor microenvironment (TME). They play a vital role in maintaining the extracellular matrix and facilitating the intricate communication between cancer cells and infiltrated immune cells. Exploring therapeutic approaches targeting CAFs may reverse the current landscape of PC therapy. In recent years, nano-drug delivery systems have evolved rapidly and have been able to accurately target and precisely release drugs with little or no toxicity to the whole body. In this review, we will comprehensively discuss the origin, heterogeneity, potential targets, and recent advances in the nano-drug delivery system of CAFs in PC. We will also propose a novel integrated treatment regimen that utilizes a nano-drug delivery system to target CAFs in PC, combined with radiotherapy and immunotherapy. Additionally, we will address the challenges that this regimen currently faces.

Cancer immune exclusion: breaking the barricade for a successful immunotherapy

Immunotherapy has changed the course of cancer treatment. The initial steps were made through tumor-specific antibodies that guided the setup of an antitumor immune response. A new and successful generation of antibodies are designed to target immune checkpoint molecules aimed to reinvigorate the antitumor immune response. The cellular counterpart is the adoptive cell therapy, where specific immune cells are expanded or engineered to target cancer cells. In all cases, the key for achieving positive clinical resolutions rests upon the access of immune cells to the tumor. In this review, we focus on how the tumor microenvironment architecture, including stromal cells, immunosuppressive cells and extracellular matrix, protects tumor cells from an immune attack leading to immunotherapy resistance, and on the available strategies to tackle immune evasion.

Controversial role of γδ T cells in pancreatic cancer

γδ T cells are rare lymphocytes with cogent impact on immune responses. These cells are one of the earliest cells to be recruited in the sites of infection or tumors and play a critical role in coordinating innate and adaptive immune responses. The anti-tumor activity of γδ T cells have been numerously reported; nonetheless, there is controversy among published studies regarding their anti-tumor vs pro-tumor effect- especially in pancreatic cancer. A myriad of studies has confirmed that activated γδ T cells can potently lyse a broad variety of solid tumors and leukemia/lymphoma cells and produce an array of cytokines; however, early γδ T cell-based clinical trials did not lead to optimal efficacy, despite acceptable safety. Depending on the local micromilieu, γδ T cells can differentiate into tumor promoting or suppressing cells such as Th1-, Th2-, or Th17-like cells and produce prototypical cytokines such as interferon-γ (IFNγ) and interleukin (IL)-4/-10, IL-9, or IL-17. In an abstruse tumor such as pancreatic cancer- also known as immunologically cold tumor- γδ T cells are more likely to switch to their immunosuppressive phenotype. In this review we will adduce the accumulated knowledge on these two controversial aspects of γδ T cells in cancers- with a focus on solid tumors and pancreatic cancer. In addition, we propose strategies for enhancing the anti-tumor function of γδ T cells in cancers and discuss the potential future directions.

Targeting the Tumor Extracellular Matrix by the Natural Molecule 4-Methylumbelliferone: A Complementary and Alternative Cancer Therapeutic Strategy

In antineoplastic therapy, one of the challenges is to adjust the treatment to the needs of each patient and reduce the toxicity caused by conventional antitumor strategies. It has been demonstrated that natural products with antitumoral properties are less toxic than chemotherapy and radiotherapy. Also, using already developed drugs allows developing substantially less costly methods for the discovery of new treatments than traditional drug development. Candidate molecules proposed for drug repositioning include 4-methylumbelliferone (4-MU), an orally available dietetic product, derivative of coumarin and mainly found in the plant family Umbelliferae or Apiaceae. 4-MU specifically inhibits the synthesis of glycosaminoglycan hyaluronan (HA), which is its main mechanism of action. This agent reduces the availability of HA substrates and inhibits the activity of different HA synthases. However, an effect independent of HA synthesis has also been observed. 4-MU acts as an inhibitor of tumor growth in different types of cancer. Particularly, 4-MU acts on the proliferation, migration and invasion abilities of tumor cells and inhibits the progression of cancer stem cells and the development of drug resistance. In addition, the effect of 4-MU impacts not only on tumor cells, but also on other components of the tumor microenvironment. Specifically, 4-MU can potentially act on immune, fibroblast and endothelial cells, and pro-tumor processes such as angiogenesis. Most of these effects are consistent with the altered functions of HA during tumor progression and can be interrupted by the action of 4-MU. While the potential advantage of 4-MU as an adjunct in cancer therapy could improve therapeutic efficacy and reduce toxicities of other antitumoral agents, the greatest challenge is the lack of scientific evidence to support its approval. Therefore, crucial human clinical studies have yet to be done to respond to this need. Here, we discuss and review the possible applications of 4-MU as an adjunct in conventional antineoplastic therapies, to achieve greater therapeutic success. We also describe the main proposed mechanisms of action that promote an increase in the efficacy of conventional antineoplastic strategies in different types of cancer and prospects that promote 4-MU repositioning and application in cancer therapy.

Cancer immunotherapy with γδ T cells: many paths ahead of us

γδ T cells play uniquely important roles in stress surveillance and immunity for infections and carcinogenesis. Human γδ T cells recognize and kill transformed cells independently of human leukocyte antigen (HLA) restriction, which is an essential feature of conventional αβ T cells. Vγ9Vδ2 γδ T cells, which prevail in the peripheral blood of healthy adults, are activated by microbial or endogenous tumor-derived pyrophosphates by a mechanism dependent on butyrophilin molecules. γδ T cells expressing other T cell receptor variable genes, notably Vδ1, are more abundant in mucosal tissue. In addition to the T cell receptor, γδ T cells usually express activating natural killer (NK) receptors, such as NKp30, NKp44, or NKG2D which binds to stress-inducible surface molecules that are absent on healthy cells but are frequently expressed on malignant cells. Therefore, γδ T cells are endowed with at least two independent recognition systems to sense tumor cells and to initiate anticancer effector mechanisms, including cytokine production and cytotoxicity. In view of their HLA-independent potent antitumor activity, there has been increasing interest in translating the unique potential of γδ T cells into innovative cellular cancer immunotherapies. Here, we discuss recent developments to enhance the efficacy of γδ T cell-based immunotherapy. This includes strategies for in vivo activation and tumor-targeting of γδ T cells, the optimization of in vitro expansion protocols, and the development of gene-modified γδ T cells. It is equally important to consider potential synergisms with other therapeutic strategies, notably checkpoint inhibitors, chemotherapy, or the (local) activation of innate immunity.

The Ovarian Cancer Tumor Immune Microenvironment (TIME) as Target for Therapy: A Focus on Innate Immunity Cells as Therapeutic Effectors

Ovarian cancer (OvCA) accounts for one of the leading causes of death from gynecologic malignancy. Despite progress in therapy improvements in OvCA, most patients develop a recurrence after first-line treatments, dependent on the tumor and non-tumor complexity/heterogeneity of the neoplasm and its surrounding tumor microenvironment (TME). The TME has gained greater attention in the design of specific therapies within the new era of immunotherapy. It is now clear that the immune contexture in OvCA, here referred as tumor immune microenvironment (TIME), acts as a crucial orchestrator of OvCA progression, thus representing a necessary target for combined therapies. Currently, several advancements of antitumor immune responses in OvCA are based on the characterization of tumor-infiltrating lymphocytes, which have been shown to correlate with a significantly improved clinical outcome. Here, we reviewed the literature on selected TIME components of OvCA, such as macrophages, neutrophils, γδ T lymphocytes, and natural killer (NK) cells; these cells can have a role in either supporting or limiting OvCA, depending on the TIME stimuli. We also reviewed and discussed the major (immune)-therapeutic approaches currently employed to target and/or potentiate macrophages, neutrophils, γδ T lymphocytes, and NK cells in the OvCA context.