Targeted Therapy for Highly Desmoplastic and Immunosuppressive Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a very poor prognosis. Despite advancements in treatment strategies, PDAC remains recalcitrant to therapies because patients are often diagnosed at an advanced stage. The advanced stage of PDAC is characterized by metastasis, which typically renders it unresectable by surgery or untreatable by chemotherapy. The tumor microenvironment (TME) of PDAC comprises highly proliferative myofibroblast-like cells and hosts the intense deposition of a extracellular matrix component that forms dense fibrous connective tissue, a process called the desmoplastic reaction. In desmoplastic TMEs, the incessant aberration of signaling pathways contributes to immunosuppression by suppressing antitumor immunity. This feature offers a protective barrier that impedes the targeted delivery of drugs. In addition, the efficacy of immunotherapy is compromised because of the immune cold TME of PDAC. Targeted therapy approaches towards stromal and immunosuppressive TMEs are challenging. In this review, we discuss cellular and non-cellular TME components that contain actionable targets for drug development. We also highlight findings from preclinical studies and provide updates about the efficacies of new investigational drugs in clinical trials.

Latest Progress in Risk-Adapted Surgery for Medullary Thyroid Cancer

(1) Background: The wider adoption of a preoperative ultrasound and calcitonin screening complemented by an intraoperative frozen section has increased the number of patients with occult sporadic medullary thyroid cancer (MTC). These advances offer new opportunities to reduce the extent of the initial operations, minimizing operative morbidity and the risk of postoperative thyroxin supplementation without compromising the cure. (2) Methods: This systematic review of the international literature published in the English language provides a comprehensive update on the latest progress made in the risk-adapted surgery for sporadic and hereditary MTC guided by an intraoperative frozen section. (3) Results: The current evidence confirms the viability of a hemithyroidectomy for desmoplasia-negative sporadic MTC. To add an extra safety margin, the hemithyroidectomy may be complemented by a diagnostic ipsilateral central node dissection. Despite the limited extent of the surgery, all the patients with desmoplasia-negative sporadic tumors achieved a biochemical cure with excellent clinical outcomes. A hemithyroidectomy decreases the need for postoperative thyroxine substitution, but a total thyroidectomy may be required for bilateral nodular thyroid disease. Hereditary MTC is a different issue. Because each residual thyroid C cell carries its own risk of malignant progression, a total thyroidectomy remains mandatory for hereditary MTC. (4) Conclusion: In experienced hands, a hemithyroidectomy, which minimizes morbidity without compromising the cure, is an adequate therapy for desmoplasia-negative sporadic MTC.

Desmoplastic stromal signatures predict patient outcomes in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second leading cause of cancer-related death. Hallmarks include desmoplasia with variable extracellular matrix (ECM) architecture and a complex microenvironment with spatially defined tumor, stromal, and immune populations. Nevertheless, the role of desmoplastic spatial organization in patient/tumor variability remains underexplored, which we elucidate using two technologies. First, we quantify ECM patterning in 437 patients, revealing architectures associated with disease-free and overall survival. Second, we spatially profile the cellular milieu of 78 specimens using codetection by indexing, identifying an axis of pro-inflammatory cell interactions predictive of poorer outcomes. We discover that clinical characteristics, including neoadjuvant chemotherapy status, tumor stage, and ECM architecture, correlate with differential stromal-immune organization, including fibroblast subtypes with distinct niches. Lastly, we define unified signatures that predict survival with areas under the receiver operating characteristic curve (AUCs) of 0.872-0.903, differentiating survivorship by 655 days. Overall, our findings establish matrix ultrastructural and cellular organizations of fibrosis linked to poorer outcomes.

Fibroblast-derived matrix models desmoplastic properties and forms a prognostic signature in cancer progression

The desmoplastic reaction observed in many cancers is a hallmark of disease progression and prognosis, particularly in breast and pancreatic cancer. Stromal-derived extracellular matrix (ECM) is significantly altered in desmoplasia, and as such plays a critical role in driving cancer progression. Using fibroblast-derived matrices (FDMs), we show that cancer cells have increased growth on cancer associated FDMs, when compared to FDMs derived from non-malignant tissue (normal) fibroblasts. We assess the changes in ECM characteristics from normal to cancer-associated stroma at the primary tumor site. Compositional, structural, and mechanical analyses reveal significant differences, with an increase in abundance of core ECM proteins, coupled with an increase in stiffness and density in cancer-associated FDMs. From compositional changes of FDM, we derived a 36-ECM protein signature, which we show matches in large part with the changes in pancreatic ductal adenocarcinoma (PDAC) tumor and metastases progression. Additionally, this signature also matches at the transcriptomic level in multiple cancer types in patients, prognostic of their survival. Together, our results show relevance of FDMs for cancer modelling and identification of desmoplastic ECM components for further mechanistic studies.

A Comprehensive Transcriptional Signature in Pancreatic Ductal Adenocarcinoma Reveals New Insights into the Immune and Desmoplastic Microenvironments

Pancreatic ductal adenocarcinoma (PDAC) prognoses and treatment responses remain devastatingly poor due partly to the highly heterogeneous, aggressive, and immunosuppressive nature of this tumor type. The intricate relationship between the stroma, inflammation, and immunity remains vaguely understood in the PDAC microenvironment. Here, we performed a meta-analysis of stroma-, and immune-related gene expression in the PDAC microenvironment to improve disease prognosis and therapeutic development. We selected 21 PDAC studies from the Gene Expression Omnibus and ArrayExpress databases, including 922 samples (320 controls and 602 cases). Differential gene enrichment analysis identified 1153 significant dysregulated genes in PDAC patients that contribute to a desmoplastic stroma and an immunosuppressive environment (the hallmarks of PDAC tumors). The results highlighted two gene signatures related to the immune and stromal environments that cluster PDAC patients into high- and low-risk groups, impacting patients' stratification and therapeutic decision making. Moreover, HCP5, SLFN13, IRF9, IFIT2, and IFI35 immune genes are related to the prognosis of PDAC patients for the first time.

Cholecystokinin Receptor Antagonist Induces Pancreatic Stellate Cell Plasticity Rendering the Tumor Microenvironment Less Oncogenic

CCK receptors are expressed on pancreatic cancer epithelial cells, and blockade with receptor antagonists decreases tumor growth. Activated pancreatic stellate cells or myofibroblasts have also been described to express CCK receptors, but the contribution of this novel pathway in fibrosis of the pancreatic cancer microenvironment has not been studied. We examined the effects of the nonselective CCK receptor antagonist proglumide on the activation, proliferation, collagen deposition, differential expression of genes, and migration in both murine and human PSCs. CCK receptor expression was examined using western blot analysis. Collagen production using activated PSCs was analyzed by mass spectroscopy and western blot. Migration of activated PSCs was prevented in vitro by proglumide and the CCK-B receptor antagonist, L365,260, but not by the CCK-A receptor antagonist L365,718. Proglumide effectively decreased the expression of extracellular matrix-associated genes and collagen-associated proteins in both mouse and human PSCs. Components of fibrosis, including hydroxyproline and proline levels, were significantly reduced in PSC treated with proglumide compared to controls. CCK peptide stimulated mouse and human PSC proliferation, and this effect was blocked by proglumide. These investigations demonstrate that targeting the CCK-B receptor signaling pathway with proglumide may alter the plasticity of PSC, rendering them more quiescent and leading to a decrease in fibrosis in the pancreatic cancer microenvironment.

The Tango between Cancer-Associated Fibroblasts (CAFs) and Immune Cells in Affecting Immunotherapy Efficacy in Pancreatic Cancer

The lack of response to therapy in pancreatic ductal adenocarcinoma (PDAC) patients has contributed to PDAC having one of the lowest survival rates of all cancer types. The poor survival of PDAC patients urges the exploration of novel treatment strategies. Immunotherapy has shown promising results in several other cancer types, but it is still ineffective in PDAC. What sets PDAC apart from other cancer types is its tumour microenvironment (TME) with desmoplasia and low immune infiltration and activity. The most abundant cell type in the TME, cancer-associated fibroblasts (CAFs), could be instrumental in why low immunotherapy responses are observed. CAF heterogeneity and interactions with components of the TME is an emerging field of research, where many paths are to be explored. Understanding CAF-immune cell interactions in the TME might pave the way to optimize immunotherapy efficacy for PDAC and related cancers with stromal abundance. In this review, we discuss recent discoveries on the functions and interactions of CAFs and how targeting CAFs might improve immunotherapy.

Drug Delivery Strategies for the Treatment of Pancreatic Cancer

Pancreatic cancer is fast becoming a global menace and it is projected to be the second leading cause of cancer-related death by 2030. Pancreatic adenocarcinomas, which develop in the pancreas' exocrine region, are the predominant type of pancreatic cancer, representing about 95% of total pancreatic tumors. The malignancy progresses asymptomatically, making early diagnosis difficult. It is characterized by excessive production of fibrotic stroma known as desmoplasia, which aids tumor growth and metastatic spread by remodeling the extracellular matrix and releasing tumor growth factors. For decades, immense efforts have been harnessed toward developing more effective drug delivery systems for pancreatic cancer treatment leveraging nanotechnology, immunotherapy, drug conjugates, and combinations of these approaches. However, despite the reported preclinical success of these approaches, no substantial progress has been made clinically and the prognosis for pancreatic cancer is worsening. This review provides insights into challenges associated with the delivery of therapeutics for pancreatic cancer treatment and discusses drug delivery strategies to minimize adverse effects associated with current chemotherapy options and to improve the efficiency of drug treatment.

Overcoming the Fibrotic Fortress in Pancreatic Ductal Adenocarcinoma: Challenges and Opportunities

An overabundance of desmoplasia in the tumour microenvironment (TME) is one of the defining features that influences pancreatic ductal adenocarcinoma (PDAC) development, progression, metastasis, and treatment resistance. Desmoplasia is characterised by the recruitment and activation of fibroblasts, heightened extracellular matrix deposition (ECM) and reduced blood supply, as well as increased inflammation through an influx of inflammatory cells and cytokines, creating an intrinsically immunosuppressive TME with low immunogenic potential. Herein, we review the development of PDAC, the drivers that initiate and/or sustain the progression of the disease and the complex and interwoven nature of the cellular and acellular components that come together to make PDAC one of the most aggressive and difficult to treat cancers. We review the challenges in delivering drugs into the fortress of PDAC tumours in concentrations that are therapeutic due to the presence of a highly fibrotic and immunosuppressive TME. Taken together, we present further support for continued/renewed efforts focusing on aspects of the extremely dense and complex TME of PDAC to improve the efficacy of therapy for better patient outcomes.

Nanodiamond mediated molecular targeting in Pancreatic Ductal adenocarcinoma: Disrupting the tumor-stromal cross-talk, next hope on the horizon?

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the foremost causes of cancer-related morbidities worldwide. Novel nanotechnology-backed drug delivery stratagems, including molecular targeting of the chemotherapeutic payload, have been considered. However, no quantum leap in the gross survival rate of patients with PDAC has been realized.

OBJECTIVE

One of the predominant causes behind this is tumor desmoplasia, a dense and heterogenous stromal extracellular matrix of the tumor, aptly termed tumor microenvironment (TME). It plays a pivotal role in the tumor pathogenesis of PDAC as it occupies most of the tumor mass, making PDAC one of the most stromal-rich cancers. The complex cross-talk between the tumor and dynamic components of the TME impacts tumor progression and poses a potential barrier to drug delivery. Understanding and deciphering the complex cascade of tumor-stromal interactions are the need of the hour so that we can develop neoteric nano-carriers to disrupt the stroma and target the tumor.

CONCLUSION

Nanodiamonds (NDs), due to their unique surface characteristics, have emerged as a promising nano delivery system in various pre-clinical cancer models and have the potential to deliver the chemotherapeutic payload by moving beyond the dynamic tumor-stromal barrier. It can be the next revolution in nanoparticle-mediated pancreatic cancer targeting.

Prevalence and anatomopathological characterization of cutaneous squamous cell carcinomas with regional and distant metastases in dogs and cats: 20 cases (1985-2020)

The aim of this study was to assess the prevalence of regional and distant metastases from cutaneous squamous cell carcinomas (SCCs) in dogs (n = 11) and cats (n = 9) in a retrospective case series over 36 years (1985-2020), as well as to characterize its macroscopic aspects (location and size), degree of differentiation (well, moderately and poorly differentiated [WD, MD and PD, respectively]) and the rate of cell proliferation, by counting the AgNORs. Immunohistochemistry (IHC) was used to identify patterns of tumour migration and invasion (islands, ribbons, cords, small aggregates, individual cells [fusiform and amoeboid]) and to evaluate the intensity of desmoplasia and the amount of myofibroblasts. The prevalence of metastatic SCCs was 4.39% (21/478), being 3.8% in dog (12/309) and 5.3% in cat (9/169). Metastases affected lymph nodes in all dogs and 66% (6/9) of cats, and less frequently distant organs. Primary tumours predominantly affected the abdominal skin in dogs and the nasal planum in cats. Among the 20 cases, 52% were MDs, 34% were WDs, and 14% were PDs. Histological lesions suggestive of exposure to chronic solar radiation were present in 57% (8/14). The main patterns of tumour migration and invasion were islands for WD SCCs and individual cells for PD SCCs. MD SCCs had a mix of patterns. In cats, individual spindle cells were restricted to PDs. A marked desmoplastic reaction was more associated with PD SCCs and often with MDs. This study highlights that the prevalence of SCC metastases in dogs and cats is predominantly regional. The IHC was essential in the identification of individual fusiform keratinocytes, whose presence in surgical margins may represent a greater risk of recurrence. Although the presence of myofibroblasts was observed in all infiltrative and metastatic tumours, further studies evaluating these cells may be important to better understand their role in the tumour microenvironment of cutaneous SCCs with metastasis in dogs and cats.

Cancer-Associated Fibroblast Diversity Shapes Tumor Metabolism in Pancreatic Cancer

Despite extensive research, the 5-year survival rate of pancreatic cancer (PDAC) patients remains at only 9%. Patients often show poor treatment response, due partly to a highly complex tumor microenvironment (TME). Cancer-associated fibroblast (CAF) heterogeneity is characteristic of the pancreatic TME, where several CAF subpopulations have been identified, such as myofibroblastic CAFs (myCAFs), inflammatory CAFs (iCAFs), and antigen presenting CAFs (apCAFs). In PDAC, cancer cells continuously adapt their metabolism (metabolic switch) to environmental changes in pH, oxygenation, and nutrient availability. Recent advances show that these environmental alterations are all heavily driven by stromal CAFs. CAFs and cancer cells exchange cytokines and metabolites, engaging in a tight bidirectional crosstalk, which promotes tumor aggressiveness and allows constant adaptation to external stress, such as chemotherapy. In this review, we summarize CAF diversity and CAF-mediated metabolic rewiring, in a PDAC-specific context. First, we recapitulate the most recently identified CAF subtypes, focusing on the cell of origin, activation mechanism, species-dependent markers, and functions. Next, we describe in detail the metabolic crosstalk between CAFs and tumor cells. Additionally, we elucidate how CAF-driven paracrine signaling, desmoplasia, and acidosis orchestrate cancer cell metabolism. Finally, we highlight how the CAF/cancer cell crosstalk could pave the way for new therapeutic strategies.

High beta integrin expression is differentially associated with worsened pancreatic ductal adenocarcinoma outcomes

Outcomes in pancreatic ductal adenocarcinoma (PDAC) are known to be worse in tumors with high integrin β1 expression, but targeted monotherapy against this integrin has not been effective. Seven other beta integrins are expressed in mammalian biology and they are known to have overlapping and compensatory signaling in biological systems. However, their roles in PDAC are poorly understood and have not been systematically compared to integrin β1 biology. In this study, we analyzed the clinical outcomes against beta integrin 1-8 (ITGB1-8) expression in PDAC samples from two large independent cohorts, The Cancer Genome Atlas (TCGA) and GSE21501. Biological function and tumor microenvironment composition were studied using Gene Set Enrichment Analysis and xCell. Expression of all eight beta integrins is significantly increased in PDACs relative to normal pancreatic tissues (all P<0.001). ITGB1, 2, 5, and 6 have similarly enriched gene patterns related to transforming growth factor (TGF)-β, epithelial mesenchymal transition, inflammation, stemness, and angiogenesis pathways. Homologous recombination defects and neoantigens are increased in high-ITGB4, 5, and 6 tumors, with decreased overall survival in high-ITGB1, 5, and 6 tumors compared to low expression tumors (hazard ratios 1.5-2.0). High-ITGB1, 2, and 5 tumors have increased fibroblast infiltration (all P<0.01) while endothelial cells are increased in high-ITGB2 and 3 tumors (all P<0.05). Overall, beta integrin expression does not correlate to immune cell populations in PDACs. Therefore, while all beta integrins are overexpressed in PDACs, they exert differential effects on PDAC biology. ITGB2, 5, and 6 have a similar profile to ITGB1, suggesting that future research in PDAC integrin therapy needs to consider the complementary signaling profiles mediated by these integrins.

A case of endometriotic cyst enlargement during pregnancy owing to desmoplasia and rupture at 36 weeks of gestation

Decidualized ovarian endometrioma is a rare phenomenon that occurs during pregnancy. A 43-year-old pregnant woman with an endometriotic cyst increased owing to desmoplasia presented to us urgently with abdominal pain and was performed a cesarean section at 36 weeks and 1 day of pregnancy. The left ovarian cyst was noted to be partially ruptured, and the pathological diagnosis was an endometriotic cyst with desmoplasia. Endometriotic cysts may enlarge during pregnancy owing to desmoplasia and rupture in the last trimester of pregnancy, causing acute abdomen.

CD16+ fibroblasts foster a trastuzumab-refractory microenvironment that is reversed by VAV2 inhibition

The leukocyte Fcγ receptor (FcγR)-mediated response is important for the efficacy of therapeutic antibodies; however, little is known about the role of FcγRs in other cell types. Here we identify a subset of fibroblasts in human breast cancer that express CD16 (FcγRIII). An abundance of these cells in HER2⁺ breast cancer patients is associated with poor prognosis and response to trastuzumab. Functionally, upon trastuzumab stimulation, CD16⁺ fibroblasts reduce drug delivery by enhancing extracellular matrix stiffness. Interaction between trastuzumab and CD16 activates the intracellular SYK-VAV2-RhoA-ROCK-MLC2-MRTF-A pathway, leading to elevated contractile force and matrix production. Targeting of a Rho family guanine nucleotide exchange factor, VAV2, which is indispensable for the function of CD16 in fibroblasts rather than leukocytes, reverses desmoplasia provoked by CD16⁺ fibroblasts. Collectively, our study reveals a role for the fibroblast FcγR in drug resistance, and suggests that VAV2 is an attractive target to augment the effects of antibody treatments.

Cancer-Associated Fibroblasts in Cholangiocarcinoma: Current Knowledge and Possible Implications for Therapy

Cholangiocarcinoma (CCA) is an aggressive neoplasia with an increasing incidence and mortality. It is characterized by a strong desmoplastic stroma surrounding cancer cells. Cancer-associated fibroblasts (CAFs) are the main cell type of CCA stroma and they have an important role in modulating cancer microenvironments. CAFs originate from multiple lines of cells and mainly consist of fibroblasts and alpha-smooth muscle actin (α-SMA) positive myofibroblast-like cells. The continuous cross-talking between CCA cells and desmoplastic stroma is permitted by CAF biochemical signals, which modulate a number of pathways. Stromal cell-derived factor-1 expression increases CAF recruitment to the tumor reactive stroma and influences apoptotic pathways. The Bcl-2 family protein enhances susceptibility to CAF apoptosis and PDGFRβ induces fibroblast migration and stimulates tumor lymphangiogenesis. Many factors related to CAFs may influence CCA prognosis. For instance, a better prognosis is associated with IL-33 expression and low stromal IL-6 (whose secretion is stimulated by microRNA). In contrast, a worst prognosis is given by the expression of PDGF-D, podoplanin, SDF-1, α-SMA high expression, and periostin. The maturity phenotype has a prognostic relevance too. New therapeutic strategies involving CAFs are currently under study. Promising results are obtained with anti-PlGF therapy, nintedanib (BIBF1120), navitoclax, IPI-926, resveratrol, and controlled hyperthermia.

Targeted Depletion of Hyaluronic Acid Mitigates Murine Breast Cancer Growth

Hyaluronic acid (HA) is highly elevated in breast cancers compared to normal breast tissue and is associated with increased tumor aggressiveness and poor prognosis. HA interacts with cell-trafficking CD44 receptors to promote tumor cell migration and proliferation and regulates both pro- and anti-inflammatory cytokine production through tumor-associated macrophages. The highly negative charge of HA enables its uptake of vast amounts of water that greatly increases the tumor interstitial fluidic pressure, which, combined with the presence of other extracellular matrix components such as collagen, results in tumor stroma with abnormal vasculature, hypoxia, and increased drug resistance. Thus, the degradation of HA in breast cancer may attenuate growth and improve permeability to anticancer agents. Previous methods to deplete tumor HA have resulted in significant off-tumor effects due to the systemic use of mammalian hyaluronidases. To overcome this, we developed a hyaluronidase-secreting Salmonella typhimurium (YS-HAse) that specifically and preferentially colonizes tumors to deplete HA. We show that the systemic administration of YS-HAse in immunocompetent murine models of breast cancer enhances tumor perfusion, controls tumor growth, and restructures the tumor immune contexture. These studies highlight the utility of YS-HAse as a novel microbial-based therapeutic that may also be combined with existing therapeutic approaches.

Remediating Desmoplasia with EGFR-Targeted Photoactivable Multi-Inhibitor Liposomes Doubles Overall Survival in Pancreatic Cancer

Desmoplasia is characteristic of pancreatic ductal adenocarcinoma (PDAC), which exhibits 5-year survival rates of 3%. Desmoplasia presents physical and biochemical barriers that contribute to treatment resistance, yet depleting the stroma alone is unsuccessful and even detrimental to patient outcomes. This study is the first demonstration of targeted photoactivable multi-inhibitor liposomes (TPMILs) that induce both photodynamic and chemotherapeutic tumor insult, while simultaneously remediating desmoplasia in orthotopic PDAC. TPMILs targeted with cetuximab (anti-EGFR mAb) contain lipidated benzoporphyrin derivative (BPD-PC) photosensitizer and irinotecan. The desmoplastic tumors comprise human PDAC cells and patient-derived cancer-associated fibroblasts. Upon photoactivation, the TPMILs induce 90% tumor growth inhibition at only 8.1% of the patient equivalent dose of nanoliposomal irinotecan (nal-IRI). Without EGFR targeting, PMIL photoactivation is ineffective. TPMIL photoactivation is also sixfold more effective at inhibiting tumor growth than a cocktail of Visudyne-photodynamic therapy (PDT) and nal-IRI, and also doubles survival and extends progression-free survival by greater than fivefold. Second harmonic generation imaging reveals that TPMIL photoactivation reduces collagen density by >90% and increases collagen nonalignment by >103 -fold. Collagen nonalignment correlates with a reduction in tumor burden and survival. This single-construct phototoxic, chemotherapeutic, and desmoplasia-remediating regimen offers unprecedented opportunities to substantially extend survival in patients with otherwise dismal prognoses.

Photoimmunotherapy Retains Its Anti-Tumor Efficacy with Increasing Stromal Content in Heterotypic Pancreatic Cancer Spheroids

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease characterized by increased levels of desmoplasia that contribute to reduced drug delivery and poor treatment outcomes. In PDAC, the stromal content can account for up to 90% of the total tumor volume. The complex interplay between stromal components, including pancreatic cancer-associated fibroblasts (PCAFs), and PDAC cells in the tumor microenvironment has a significant impact on the prognoses and thus needs to be recapitulated in vitro when evaluating various treatment strategies. This study is a systematic evaluation of photodynamic therapy (PDT) in 3D heterotypic coculture models of PDAC with varying ratios of patient-derived PCAFs that simulate heterogeneous PDAC tumors with increasing stromal content. The efficacy of antibody-targeted PDT (photoimmunotherapy; PIT) using cetuximab (a clinically approved anti-EGFR antibody) photoimmunoconjugates (PICs) of a benzoporphyrin derivative (BPD) is contrasted with that of liposomal BPD (Visudyne), which is currently in clinical trials for PDT of PDAC. We demonstrate that both Visudyne-PDT and PIT were effective in heterotypic PDAC 3D spheroids with a low stromal content. However, as the stromal content increases above 50% in the 3D spheroids, the efficacy of Visudyne-PDT is reduced by up to 10-fold, while PIT retains its efficacy. PIT was found to be 10-, 19-, and 14-fold more phototoxic in spheroids with 50, 75, and 90% PCAFs, respectively, as compared to Visudyne-PDT. This marked difference in efficacy is attributed to the ability of PICs to penetrate and distribute homogeneously within spheroids with a higher stromal content and the mechanistically different modes of action of the two formulations. This study thus demonstrates how the stromal content in PDAC spheroids directly impacts their responsiveness to PDT and proposes PIT to be a highly suited treatment option for desmoplastic tumors with particularly high degrees of stromal content.

Tumor Microenvironment Features and Chemoresistance in Pancreatic Ductal Adenocarcinoma: Insights into Targeting Physicochemical Barriers and Metabolism as Therapeutic Approaches

Currently, the median overall survival of PDAC patients rarely exceeds 1 year and has an overall 5-year survival rate of about 9%. These numbers are anticipated to worsen in the future due to the lack of understanding of the factors involved in its strong chemoresistance. Chemotherapy remains the only treatment option for most PDAC patients; however, the available therapeutic strategies are insufficient. The factors involved in chemoresistance include the development of a desmoplastic stroma which reprograms cellular metabolism, and both contribute to an impaired response to therapy. PDAC stroma is composed of immune cells, endothelial cells, and cancer-associated fibroblasts embedded in a prominent, dense extracellular matrix associated with areas of hypoxia and acidic extracellular pH. While multiple gene mutations are involved in PDAC initiation, this desmoplastic stroma plays an important role in driving progression, metastasis, and chemoresistance. Elucidating the mechanisms underlying PDAC resistance are a prerequisite for designing novel approaches to increase patient survival. In this review, we provide an overview of the stromal features and how they contribute to the chemoresistance in PDAC treatment. By highlighting new paradigms in the role of the stromal compartment in PDAC therapy, we hope to stimulate new concepts aimed at improving patient outcomes.

Pancreatic cancer: genetics, disease progression, therapeutic resistance and treatment strategies

Pancreatic cancer is a deadly disease and the third-highest cause of cancer-related deaths in the United States. It has a very low five-year survival rate (< 5%) in the United States as well as in the world (about 9%). The current gemcitabine-based therapy soon becomes ineffective because treatment resistance and surgical resection also provides only selective benefit. Signature mutations in pancreatic cancer confer chemoresistance by deregulating the cell cycle and promoting anti-apoptotic mechanisms. The stroma-rich tumor microenvironment impairs drug delivery and promotes tumor-specific immune escape. All these factors render the current treatment incompetent and prompt an urgent need for new, improved therapy. In this review, we have discussed the genetics of pancreatic cancer and its role in tumor evolution and treatment resistance. We have also evaluated new treatment strategies for pancreatic cancer, like targeted therapy and immunotherapy.

Autophagy in host stromal fibroblasts supports tumor desmoplasia

Growing evidence demonstrates that macroautophagy/autophagy in the host stroma influences the tumor microenvironment. We have uncovered that autophagy in host stromal fibroblasts is compulsory to initiate and maintain the desmoplastic fibrotic response that fosters mammary tumor progression. Genetic loss of fibroblast autophagy impedes COL1A/type 1 collagen secretion, which is required for the development of a stiff tissue matrix permissive for mammary tumor growth. As a result, stromal fibroblast autophagy deficiency impairs mammary tumor progression in vivo, even when the cancer cells themselves remain autophagy competent. Our results provide unique conceptual insight into how the autophagy pathway can be modulated to abolish the desmoplastic response required for cancer progression.

Current challenges in targeting tumor desmoplasia to improve the efficacy of immunotherapy

Desmoplasia is crucial for the development, progression and treatment of immune-resistant malignancies. and treatment of immune-resistant malignancies. Targeting desmoplasia-related metabolic pathways appears to be an interesting approach to expand our stock of disposable anti-tumor agents.CXCL12/CXCR4 axis inhibition reduces fibrosis, alleviates immunosuppression and significantly enhances the efficacy of PD-1 immunotherapy. CD40L substitute therapy may increase the activity of T-cells, downregulate CD40+, prolong patients' survival and prevent cancer progression. Although FAPα antagonists used in preclinical models did not lead to permanent cure, an alleviation of immune-resistance, modification of desmoplasia and a decrease in angiogenesis were observed. Targeting DDR2 may enhance the effect of anti-PD-1 treatment in multiple neoplasm cell lines and has the ability to overcome the adaptation to BRAF-targeted therapy in melanoma. Reprogramming desmoplasia could potentially cooperate not only with present treatment, but also other potential therapeutic targets. We present the most promising metabolic pathways related to desmoplasia and discuss the emerging strategies to improve the efficacy of immunotherapy.

Epigenetic Reprogramming of Tumor-Associated Fibroblasts in Lung Cancer: Therapeutic Opportunities

Simple Summary

Lung cancer is the leading cause of cancer death among both men and women, partly due to limited therapy responses. New avenues of knowledge are indicating that lung cancer cells do not form a tumor in isolation but rather obtain essential support from their surrounding host tissue rich in altered fibroblasts. Notably, there is growing evidence that tumor progression and even the current limited responses to therapies could be prevented by rescuing the normal behavior of fibroblasts, which are critical housekeepers of normal tissue function. For this purpose, it is key to improve our understanding of the molecular mechanisms driving the pathologic alterations of fibroblasts in cancer. This work provides a comprehensive review of the main molecular mechanisms involved in fibroblast transformation based on epigenetic reprogramming, and summarizes emerging therapeutic approaches to prevent or overcome the pathologic effects of tumor-associated fibroblasts.

Abstract

Lung cancer is the leading cause of cancer-related death worldwide. The desmoplastic stroma of lung cancer and other solid tumors is rich in tumor-associated fibroblasts (TAFs) exhibiting an activated/myofibroblast-like phenotype. There is growing awareness that TAFs support key steps of tumor progression and are epigenetically reprogrammed compared to healthy fibroblasts. Although the mechanisms underlying such epigenetic reprogramming are incompletely understood, there is increasing evidence that they involve interactions with either cancer cells, pro-fibrotic cytokines such as TGF-β, the stiffening of the surrounding extracellular matrix, smoking cigarette particles and other environmental cues. These aberrant interactions elicit a global DNA hypomethylation and a selective transcriptional repression through hypermethylation of the TGF-β transcription factor SMAD3 in lung TAFs. Likewise, similar DNA methylation changes have been reported in TAFs from other cancer types, as well as histone core modifications and altered microRNA expression. In this review we summarize the evidence of the epigenetic reprogramming of TAFs, how this reprogramming contributes to the acquisition and maintenance of a tumor-promoting phenotype, and how it provides novel venues for therapeutic intervention, with a special focus on lung TAFs.

Collagenase-Expressing Salmonella Targets Major Collagens in Pancreatic Cancer Leading to Reductions in Immunosuppressive Subsets and Tumor Growth

Therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC) can be attributed, in part, to a dense extracellular matrix containing excessive collagen deposition. Here, we describe a novel Salmonella typhimurium (ST) vector expressing the bacterial collagenase Streptomyces omiyaensis trypsin (SOT), a serine protease known to hydrolyze collagens I and IV, which are predominantly found in PDAC. Utilizing aggressive models of PDAC, we show that ST-SOT selectively degrades intratumoral collagen leading to decreases in immunosuppressive subsets, tumor proliferation and viability. Ultimately, we found that ST-SOT treatment significantly modifies the intratumoral immune landscape to generate a microenvironment that may be more conducive to immunotherapy.

Efficient pre-treatment for pancreatic cancer using chloroquine-loaded nanoparticles targeting pancreatic stellate cells

Pancreatic stellate cells (PSCs) play a key role in desmoplastic stroma, which is a characteristic of pancreatic ductal adenocarcinoma (PDAC), and they also enhance the malignancy of pancreatic cancer cells. Our previous study reported chloroquine's mitigating effects on PSC activation; however, the drug is known to induce adverse effects in clinical practice. The present study aimed to reduce chloroquine doses and develop a useful pre-treatment that targets PSCs using nanoparticles. Poly lactic-co-glycolic acid (PLGA) nanoparticles were used as carriers and loaded with indocyanine green (Nano-ICG) or chloroquine (Nano-CQ). Tumor accumulation of Nano-ICG was evaluated using an in vivo imaging system. The effects of chloroquine, Nano-CQ and/or chemotherapy drug gemcitabine were investigated in an orthotopic xenograft mouse model. Nano-ICG selectively accumulated in pancreatic tumors and persisted therein for over 7 days after administration. Additionally, Nano-ICG accumulated in the peritoneal metastasized regions, but not in the liver, kidney and normal pancreatic tissues. Nano-CQ reduced the density of activated PSCs at lower chloroquine doses and significantly restrained tumor progression in combination with gemcitabine. In conclusion, the PLGA nanosystem successfully delivered the drug to pancreatic tumors. Nano-CQ efficiently reduced PSC activation and may be a promising novel pre-treatment strategy for PDAC.

Tumor Microenvironment Alters Chemoresistance of Hepatocellular Carcinoma Through CYP3A4 Metabolic Activity

Variations in tumor biology from patient to patient combined with the low overall survival rate of hepatocellular carcinoma (HCC) present significant clinical challenges. During the progression of chronic liver diseases from inflammation to the development of HCC, microenvironmental properties, including tissue stiffness and oxygen concentration, change over time. This can potentially impact drug metabolism and subsequent therapy response to commonly utilized therapeutics, such as doxorubicin, multi-kinase inhibitors (e.g., sorafenib), and other drugs, including immunotherapies. In this study, we utilized four common HCC cell lines embedded in 3D collagen type-I gels of varying stiffnesses to mimic normal and cirrhotic livers with environmental oxygen regulation to quantify the impact of these microenvironmental factors on HCC chemoresistance. In general, we found that HCC cells with higher baseline levels of cytochrome p450-3A4 (CYP3A4) enzyme expression, HepG2 and C3Asub28, exhibited a cirrhosis-dependent increase in doxorubicin chemoresistance. Under the same conditions, HCC cell lines with lower CYP3A4 expression, HuH-7 and Hep3B2, showed a decrease in doxorubicin chemoresistance in response to an increase in microenvironmental stiffness. This differential therapeutic response was correlated with the regulation of CYP3A4 expression levels under the influence of stiffness and oxygen variation. In all tested HCC cell lines, the addition of sorafenib lowered the required doxorubicin dose to induce significant levels of cell death, demonstrating its potential to help reduce systemic doxorubicin toxicity when used in combination. These results suggest that patient-specific tumor microenvironmental factors, including tissue stiffness, hypoxia, and CYP3A4 activity levels, may need to be considered for more effective use of chemotherapeutics in HCC patients.

Loss of Nitric Oxide Induces Fibrogenic Response in Organotypic 3D Co-Culture of Mammary Epithelia and Fibroblasts-An Indicator for Breast Carcinogenesis

Simple Summary

Fibrosis, which is often caused by chronic diseases and environmental substances, is closely associated with cancer. Thus, the development of a robust method allowing for deep studies of the linkage between fibrosis and cancer is essential. Here, we tested whether our novel three-dimensional (3D) co-culture of breast epithelia and fibroblasts would be a suitable model for that purpose. We compared the phenotypic effects of L-NAME, an inhibitor of nitric oxide (NO) production, on 3D mono- and co-cultures. We previously reported that prolonged NO depletion with L-NAME caused fibrosis and tumorigenesis in mouse mammary glands. Such in vivo effects of L-NAME were well recapitulated in 3D co-cultures, but not in 3D mono-cultures of epithelia and fibroblasts. These results support not only the essential roles of the presence of the stroma in cancer development, but also the utility of this co-culture in studying the causal relationship between fibrosis and cancer.

Abstract

Excessive myofibroblast activation, which leads to dysregulated collagen deposition and the stiffening of the extracellular matrix (ECM), plays pivotal roles in cancer initiation and progression. Cumulative evidence attests to the cancer-causing effects of a number of fibrogenic factors found in the environment, diseases and drugs. While identifying such factors largely depends on epidemiological studies, it would be of great importance to develop a robust in vitro method to demonstrate the causal relationship between fibrosis and cancer. Here, we tested whether our recently developed organotypic three-dimensional (3D) co-culture would be suitable for that purpose. This co-culture system utilizes the discontinuous ECM to separately culture mammary epithelia and fibroblasts in the discrete matrices to model the complexity of the mammary gland. We observed that pharmaceutical deprivation of nitric oxide (NO) in 3D co-cultures induced myofibroblast differentiation of the stroma as well as the occurrence of epithelial–mesenchymal transition (EMT) of the parenchyma. Such in vitro response to NO deprivation was unique to co-cultures and closely mimicked the phenotype of NO-depleted mammary glands exhibiting stromal desmoplasia and precancerous lesions undergoing EMT. These results suggest that this novel 3D co-culture system could be utilized in the deep mechanistic studies of the linkage between fibrosis and cancer.

Tumor DDR1 deficiency reduces liver metastasis by colon carcinoma and impairs stromal reaction

Tumor DDR1 acts as a key factor during the desmoplastic response surrounding hepatic colorectal metastasis. Hepatic sinusoidal cell-derived soluble factors stimulate tumor DDR1 activation. DDR1 modulates matrix remodeling to promote metastasis in the liver through the interaction with hepatic stromal cells, specifically liver sinusoidal endothelial cells and hepatic stellate cells.

The Dynamic Interaction between Extracellular Matrix Remodeling and Breast Tumor Progression

Desmoplastic tumors correspond to a unique tissue structure characterized by the abnormal deposition of extracellular matrix. Breast tumors are a typical example of this type of lesion, a property that allows its palpation and early detection. Fibrillar type I collagen is a major component of tumor desmoplasia and its accumulation is causally linked to tumor cell survival and metastasis. For many years, the desmoplastic phenomenon was considered to be a reaction and response of the host tissue against tumor cells and, accordingly, designated as "desmoplastic reaction". This notion has been challenged in the last decades when desmoplastic tissue was detected in breast tissue in the absence of tumor. This finding suggests that desmoplasia is a preexisting condition that stimulates the development of a malignant phenotype. With this perspective, in the present review, we analyze the role of extracellular matrix remodeling in the development of the desmoplastic response. Importantly, during the discussion, we also analyze the impact of obesity and cell metabolism as critical drivers of tissue remodeling during the development of desmoplasia. New knowledge derived from the dynamic remodeling of the extracellular matrix may lead to novel targets of interest for early diagnosis or therapy in the context of breast tumors.

Tissue-Engineering the Fibrous Pancreatic Tumour Stroma Capsule in 3D Tumouroids to Demonstrate Paclitaxel Response

Pancreatic cancer is a unique cancer in that up to 90% of its tumour mass is composed of a hypovascular and fibrotic stroma. This makes it extremely difficult for chemotherapies to be delivered into the core of the cancer mass. We tissue-engineered a biomimetic 3D pancreatic cancer ("tumouroid") model comprised of a central artificial cancer mass (ACM), containing MIA Paca-2 cells, surrounded by a fibrotic stromal compartment. This stromal compartment had a higher concentration of collagen type I, fibronectin, laminin, and hyaluronic acid (HA) than the ACM. The incorporation of HA was validated with alcian blue staining. Response to paclitaxel was determined in 2D MIA Paca-2 cell cultures, the ACMs alone, and in simple and complex tumouroids, in order to demonstrate drug sensitivity within pancreatic tumouroids of increasing complexity. The results showed that MIA Paca-2 cells grew into the complex stroma and invaded as cell clusters with a maximum distance of 363.7 µm by day 21. In terms of drug response, the IC50 for paclitaxel for MIA Paca-2 cells increased from 0.819 nM in 2D to 3.02 nM in ACMs and to 5.87 nM and 3.803 nM in simple and complex tumouroids respectively, indicating that drug penetration may be significantly reduced in the latter. The results demonstrate the need for biomimetic models during initial drug testing and evaluation.

Enriched cancer stem cells, dense stroma, and cold immunity: Interrelated events in pancreatic cancer

Cold tumors generally show low mutational burden and low infiltration of effector T cells. The pancreas, prostate, ovary, breast, and colon are placed into the category of cold tumors. In such tumors, effector T cells are either excluded from the tumor area or taken away from being in contact with tumor cells. The stromal reaction in the form of desmoplasia is important for the pathogenesis of tumors like the pancreas. Besides acting as a barrier for the penetration of drugs into the tumor area, the dense stroma presumably creates an immunosuppressive tumor microenvironment (TME), which accounts for low responses from tumor to immunotherapy. Cancer stem cells (CSCs) are an important part of the immunosuppressive complex within the TME. The presence of CSCs within the TME is related negatively to the activity of the antitumor immune system. Here, the question is how desmoplastic aggregates can influence the functionality of CSCs for promoting a cold pancreatic tumor immunity? This review is aimed at responding to this question, the disruption of which can be an effective strategy for improving responses from cold tumors to immunotherapy.

Calpain-Associated Proteolytic Regulation of the Stromal Microenvironment in Cancer

BACKGROUND

Normalization of the stromal microenvironment is a promising strategy for cancer control. Cancer-associated fibroblasts, tumor-associated macrophages, and mesenchymal stromal cells have a central role in stromal functions. Accordingly, understanding these stromal cells is indispensable for the development of next-generation cancer therapies. Growing evidence suggests that calpain-induced intracellular proteolysis is responsible for cancer growth and stromal regulation. Calpain is a family of stress-responsive intracellular proteases and is inducible in cancer and stromal cells during carcinogenesis.

OBJECTIVE

Here, we shed light on the recent advances that have been made in understanding how calpain contributes to stromal regulation in cancer.

CONCLUSIONS

Calpains are activated in stromal cells, including pancreatic stellate cells and mesenchymal cells, thereby inducing fibrogenic responses in cancer stroma. Moreover, these molecules contribute to epithelial-mesenchymal transition and endothelial-mesenchymal transition to provide mesenchymal stromal cells in the microenvironment, and concomitantly participate in cancer angiogenesis. In addition to the conventional calpains, the unconventional calpain-9 is associated with epithelial-mesenchymal transition. Animal experiments showed that targeting calpain systems antagonizes cancer development; thus, this approach is promising for cancer control.

The Tumor Microenvironment in Liver Metastases from Colorectal Carcinoma in the Context of the Histologic Growth Patterns

Colorectal carcinoma (CRC) is the third most common cancer. Likewise, it is a disease that has a long survival if it is prematurely detected. However, more than 50% of patients will develop metastases, mainly in the liver (LM-CRC), throughout the evolution of their disease, which accounts for most CRC-related deaths. Treatment it is certainly a controversial issue, since it has not been shown to increase overall survival in the adjuvant setting, although it does improve disease free survival (DFS). Moreover, current chemotherapy combinations are administered based on data extrapolated from primary tumors (PT), not considering that LM-CRC present a very particular tumor microenvironment that can radically condition the effectiveness of treatments designed for a PT. The liver has a particular histology and microenvironment that can determine tumor growth and response to treatments: double blood supply, vascularization through fenestrated sinusoids and the presence of different mesenchymal cell types, among other particularities. Likewise, the liver presents a peculiar immune response against tumor cells, a fact that correlates with the poor response to immunotherapy. All these aspects will be addressed in this review, putting them in the context of the histological growth patterns of LM-CRC, a particular pathologic feature with both prognostic and predictive repercussions.

Desmoplastic mesenteric lesions do not respond radiographically to peptide receptor radionuclide therapy

¹⁷⁷ Lu-Dotatate treatment is indicated for progressive, well-differentiated, small bowel neuroendocrine tumours) NETs. These tumours often metastasise to mesenteric lymph nodes and produce a desmoplastic reaction, consisting of tumour cells interspersed with fibrotic tissue. We hypothesised that, in patients treated with ¹⁷⁷ Lu-Dotatate, mesenteric tumours would remain stable even as liver tumour size changes were observed. We retrospectively reviewed the records of all patients treated with ¹⁷⁷ Lu-Dotatate between April 2018 and December 2019. Among patients with desmoplastic mesenteric tumours and liver metastases, we evaluated changes in tumour size of mesenteric and liver lesions based on pre- and post-treatment anatomic scans. As a result of the infrequency of objective radiographic response, any reported changes in tumour size were considered significant. Twenty-one patients met the inclusion criteria: nine had evidence of shrinkage of liver lesion(s), one had mild progression of liver lesions, seven had stable hepatic disease and four had a mixed hepatic response. Two of the patients with hepatic tumour shrinkage met the criteria for a partial response via RECIST 1.1 (https://recist.eortc.org). Desmoplastic mesenteric lesions remained unchanged in size, regardless of the changes detected in liver lesions. In conclusion, ¹⁷⁷ Lu-Dotatate does not impact desmoplastic mesenteric tumours which are typically associated with midgut NETs. Patients whose disease is predominantly confined to desmoplastic mesenteric lesions are unlikely to respond radiographically to peptide receptor radionuclide therapy. Moreover, the inclusion of desmoplastic mesenteric lesions as target lesions in RECIST measurements tends to increase rates of disease stability vs response or progression.

Emerging Kinase Therapeutic Targets in Pancreatic Ductal Adenocarcinoma and Pancreatic Cancer Desmoplasia

Kinase drug discovery represents an active area of therapeutic research, with previous pharmaceutical success improving patient outcomes across a wide variety of human diseases. In pancreatic ductal adenocarcinoma (PDAC), innovative pharmaceutical strategies such as kinase targeting have been unable to appreciably increase patient survival. This may be due, in part, to unchecked desmoplastic reactions to pancreatic tumors. Desmoplastic stroma enhances tumor development and progression while simultaneously restricting drug delivery to the tumor cells it protects. Emerging evidence indicates that many of the pathologic fibrotic processes directly or indirectly supporting desmoplasia may be driven by targetable protein tyrosine kinases such as Fyn-related kinase (FRK); B lymphoid kinase (BLK); hemopoietic cell kinase (HCK); ABL proto-oncogene 2 kinase (ABL2); discoidin domain receptor 1 kinase (DDR1); Lck/Yes-related novel kinase (LYN); ephrin receptor A8 kinase (EPHA8); FYN proto-oncogene kinase (FYN); lymphocyte cell-specific kinase (LCK); tec protein kinase (TEC). Herein, we review literature related to these kinases and posit signaling networks, mechanisms, and biochemical relationships by which this group may contribute to PDAC tumor growth and desmoplasia.

Tumour-stroma ratio has poor prognostic value in non-pedunculated T1 colorectal cancer: A multi-centre case-cohort study

BACKGROUND

Current risk stratification models for early invasive (T1) colorectal cancer are not able to discriminate accurately between prognostic favourable and unfavourable tumours, resulting in over-treatment of a large (>80%) proportion of T1 colorectal cancer patients. The tumour-stroma ratio (TSR), which is a measure for the relative amount of desmoplastic tumour stroma, is reported to be a strong independent prognostic factor in advanced-stage colorectal cancer, with a high stromal content being associated with worse prognosis and survival. We aimed to investigate whether the TSR predicts clinical outcome in patients with non-pedunculated T1 colorectal cancer.

METHODS

Hematoxylin and eosin (H&E)-stained tumour tissue slides from a retrospective multi-centre case cohort of patients with non-pedunculated surgically treated T1 colorectal cancer were assessed for TSR by two independent observers who were blinded for clinical outcomes. The primary end point was adverse outcome, which was defined as the presence of lymph node metastasis in the resection specimen or colorectal cancer recurrence during follow-up.

RESULTS

All 261 patients in the case cohort had H&E slides available for TSR scoring. Of these, 183 were scored as stroma-low, and 78 were scored as stroma-high. There was moderate inter-observer agreement (κ = 0.42). In total, 41 patients had lymph node metastasis, 17 patients had recurrent cancer and five had both. Stroma-high tumours were not associated with an increased risk for an adverse outcome (adjusted hazard ratio = 0.66, 95% confidence interval 0.37-1.18; p = 0.163).

CONCLUSIONS

Our study emphasises that existing prognosticators may not be simply extrapolated to T1 colorectal cancers, even though their prognostic value has been widely validated in more advanced-stage tumours.

Kinome Array Profiling of Patient-Derived Pancreatic Ductal Adenocarcinoma Identifies Differentially Active Protein Tyrosine Kinases

Pancreatic cancer remains one of the most difficult malignancies to treat. Minimal improvements in patient outcomes and persistently abysmal patient survival rates underscore the great need for new treatment strategies. Currently, there is intense interest in therapeutic strategies that target tyrosine protein kinases. Here, we employed kinome arrays and bioinformatic pipelines capable of identifying differentially active protein tyrosine kinases in different patient-derived pancreatic ductal adenocarcinoma (PDAC) cell lines and wild-type pancreatic tissue to investigate the unique kinomic networks of PDAC samples and posit novel target kinases for pancreatic cancer therapy. Consistent with previously described reports, the resultant peptide-based kinome array profiles identified increased protein tyrosine kinase activity in pancreatic cancer for the following kinases: epidermal growth factor receptor (EGFR), fms related receptor tyrosine kinase 4/vascular endothelial growth factor receptor 3 (FLT4/VEGFR-3), insulin receptor (INSR), ephrin receptor A2 (EPHA2), platelet derived growth factor receptor alpha (PDGFRA), SRC proto-oncogene kinase (SRC), and tyrosine kinase non receptor 2 (TNK2). Furthermore, this study identified increased activity for protein tyrosine kinases with limited prior evidence of differential activity in pancreatic cancer. These protein tyrosine kinases include B lymphoid kinase (BLK), Fyn-related kinase (FRK), Lck/Yes-related novel kinase (LYN), FYN proto-oncogene kinase (FYN), lymphocyte cell-specific kinase (LCK), tec protein kinase (TEC), hemopoietic cell kinase (HCK), ABL proto-oncogene 2 kinase (ABL2), discoidin domain receptor 1 kinase (DDR1), and ephrin receptor A8 kinase (EPHA8). Together, these results support the utility of peptide array kinomic analyses in the generation of potential candidate kinases for future pancreatic cancer therapeutic development.

Protective Desmoplasia in Pancreatic Adenocarcinoma: High Vitamin D Receptor Expression and Collagen Content

BACKGROUND/AIM

Vitamin D receptor (VDR) has been shown to suppress desmoplasia in pancreatic ductal adenocarcinoma (PDAC). Our aim was to assess the clinical effects of VDR expression and its correlation with collagen content in the desmoplasia of PDAC patients.

PATIENTS AND METHODS

This is a retrospective analysis of 127 patients with peritumoral desmoplasia resected for PDAC. VDR expression and collagen content were assessed by immunohistochemistry and correlated with clinical outcome.

RESULTS

Patients were classified into those with high and those with low VDR expression. High VDR expression was associated with improved overall survival (OS) in localized disease (N0) (median= 33; 95%CI=26.4-39.6 vs. 18; 15.5-20.5 months, p=0.01). Patients with high vs. low collagen content had improved OS [34, (range=22.3-45.6 months) vs. 17, (range=14.4-19.6 months), p<0.001]. The number of VDR+ cells was the same for patients with either high or low collagen content.

CONCLUSION

Protective desmoplasia is associated with increased VDR expression and collagen content.

Besieging the Tumoral Sites: Could It Be an Alternative Therapeutic Strategy in Ductal Pancreatic Adenocarcinoma?

Pancreatic ductal adenocarcinoma is characterized by its high morbidity, and curative drugs are still lacking. In addition to immunotherapy, other molecular targeted therapeutics, such as stroma depleting agents, have been evaluated, given the abundant desmoplastic stroma that is considered a protective shield for tumor cells. However, the unexpected poor outcome has raised the debate on whether desmoplasia promotes or restrains tumor cell spread. After reviewing these key points in this paper, an approach taking advantage of desmoplasia and immune cells to besiege the tumoral sites will be proposed. Based on the available literature, the feasibility and potential limitations of this strategy will be discussed.

Knowing the unknown in oral squamous cell carcinoma: An observational study

Introduction

Conventional oral squamous cell carcinoma (OSCC) is relatively easy to diagnose on histopathology, as it comprises dysplastic epithelial cells with variable degrees of squamous differentiation. Different grading systems have been employed in grading OSCC based on its dysplastic features and host response. Some unusual features such as clear cell change, epithelial-mesenchymal transition (EMT), stromal hyalinization, stromal desmoplasia, perineural invasion, vascular invasion, tissue eosinophilia, giant cells, and tertiary lymphoid follicle formation are evident in OSCC histologically but have not yet been accounted in any grading systems of OSCC except perineural and vascular invasion.

Aim

The aim of the present study was to identify these uncommon features and to correlate them with different grades of OSCC.Materials and Methods:This study was conducted on 100 histopathologically confirmed OSCC cases retrieved from the archives of our department. They were graded on the basis of Broder's grading system and were reviewed for the features mentioned above. Data collected were subjected to statistical analysis.

Results

Clear cell change, EMT, foreign body giant cells, and tumor giant cells were observed in 13%, 20%, 1%, and 3% of cases, respectively. We found stromal desmoplasia in 15% and stromal hyalinization in 9% of cases. Tissue eosinophilia, tertiary lymphoid follicle formation, and perineural invasion were observed in 12%, 3%, and 2% of cases, respectively. Vascular invasion was not evident in any of the cases examined.

Conclusion

The incidence of the unusual features was 7.8% in our study.

Angiotensin Inhibition, TGF-β and EMT in Cancer

Angiotensin inhibitors are standard drugs in cardiovascular and renal diseases that have antihypertensive and antifibrotic properties. These drugs also exert their antifibrotic effects in cancer by reducing collagen and hyaluronan deposition in the tumor stroma, thus enhancing drug delivery. Angiotensin II signaling interferes with the secretion of the cytokine TGF-β-a known driver of malignancy. TGF-β stimulates matrix production in cancer-associated fibroblasts, and thus drives desmoplasia. The effect of TGF-β on cancer cells itself is stage-dependent and changes during malignant progression from inhibitory to stimulatory. The intracellular signaling for the TGF-β family can be divided into an SMAD-dependent canonical pathway and an SMAD-independent noncanonical pathway. These capabilities have made TGF-β an interesting target for numerous drug developments. TGF-β is also an inducer of epithelial-mesenchymal transition (EMT). EMT is a highly complex spatiotemporal-limited process controlled by a plethora of factors. EMT is a hallmark of metastatic cancer, and with its reversal, an important step in the metastatic cascade is characterized by a loss of epithelial characteristics and/or the gain of mesenchymal traits.

Targeting desmoplasia in pancreatic cancer as an essential first step to effective therapy

Pancreatic cancer is considered one of the most lethal cancers in the US. It contributes to an estimated 47,000 deaths annually and is predicted to surpass prostate, breast and colorectal cancers as the leading cause of cancer-related death. Although major advancements in cancer treatment have improved outcomes for many cancer types, survival rate for pancreatic cancer has not improved in nearly four decades despite tremendous effort. One attribute of pancreatic cancer that is considered a major barrier to effective treatment is the formation of fibrotic tissue around tumor cells known as desmoplasia. A number of promising approaches have been developed to deplete fibrotic components in pancreatic tumors to enhance drug delivery, some of which have been tested in clinical trials of advanced, unresectable pancreatic cancer. Here, we discuss previous efforts, shortcomings and new considerations for developing more effective agents to eliminate desmoplasia.

Cancer-associated fibroblasts downregulate type I interferon receptor to stimulate intratumoral stromagenesis

Activation of cancer-associated fibroblasts (CAFs) and ensuing desmoplasia play an important role in the growth and progression of solid tumors. Here we demonstrate that, within colon and pancreatic ductal adenocarcinoma tumors, efficient stromagenesis relies on downregulation of the IFNAR1 chain of the type I interferon (IFN1) receptor. Expression of the fibroblast activation protein (FAP) and accumulation of the extracellular matrix (ECM) was notably impaired in tumors grown in the Ifnar1S526A (SA) knock-in mice, which are deficient in IFNAR1 downregulation. Primary fibroblasts from these mice exhibited elevated levels of Smad7, a negative regulator of the transforming growth factor-β (TGFβ) pathway. Knockdown of Smad7 alleviated deficient ECM production in SA fibroblasts in response to TGFβ. Analysis of human colorectal cancers revealed an inverse correlation between IFNAR1 and FAP levels. Whereas growth of tumors in SA mice was stimulated by co-injection of wild type but not SA fibroblasts, genetic ablation of IFNAR1 in fibroblasts also accelerated tumor growth. We discuss how inactivation of IFNAR1 in CAFs acts to stimulate stromagenesis and tumor growth.

Are Epithelial Ovarian Cancers of the Mesenchymal Subtype Actually Intraperitoneal Metastases to the Ovary?

Primary ovarian high-grade serous carcinoma (HGSC) has been classified into 4 molecular subtypes: Immunoreactive, Proliferative, Differentiated, and Mesenchymal (Mes), of which the Mes subtype (Mes-HGSC) is associated with the worst clinical outcomes. We propose that Mes-HGSC comprise clusters of cancer and associated stromal cells that detached from tumors in the upper abdomen/omentum and disseminated in the peritoneal cavity, including to the ovary. Using comparative analyses of multiple transcriptomic data sets, we provide the following evidence that the phenotype of Mes-HGSC matches the phenotype of tumors in the upper abdomen/omentum: (1) irrespective of the primary ovarian HGSC molecular subtype, matched upper abdominal/omental metastases were typically of the Mes subtype, (2) the Mes subtype was present at the ovarian site only in patients with concurrent upper abdominal/omental metastases and not in those with HGSC confined to the ovary, and (3) ovarian Mes-HGSC had an expression profile characteristic of stromal cells in the upper abdominal/omental metastases. We suggest that ovarian Mes-HGSC signifies advanced intraperitoneal tumor dissemination to the ovary rather than a subtype of primary ovarian HGSC. This is consistent with the presence of upper abdominal/omental disease, suboptimal debulking, and worst survival previously reported in patients with ovarian Mes-HGSC compared to other molecular subtypes.

CXCR2 signaling promotes secretory cancer-associated fibroblasts in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most challenging malignancies. Desmoplasia and tumor-supporting inflammation are hallmarks of PDAC. The tumor microenvironment contributes significantly to tumor progression and spread. Cancer-associated fibroblasts (CAFs) facilitate therapy resistance and metastasis. Recent reports emphasized the concurrence of multiple subtypes of CAFs with diverse roles, fibrogenic, and secretory. C-X-C motif chemokine receptor 2 (CXCR2) is a chemokine receptor known for its role during inflammation and its adverse role in PDAC. Oncogenic Kras upregulates CXCR2 and its ligands and, thus, contribute to tumor proliferation and immunosuppression. CXCR2 deletion in a PDAC syngeneic mouse model produced increased fibrosis revealing a potential undescribed role of CXCR2 in CAFs. In this study, we demonstrate that the oncogenic Kras-CXCR2 axis regulates the CAFs function in PDAC and contributes to CAFs heterogeneity. We observed that oncogenic Kras and CXCR2 signaling alter CAFs, producing a secretory CAF phenotype with low fibrogenic features; and increased secretion of pro-tumor cytokines and CXCR2 ligands, utilizing the NF-κB activity. Finally, using syngeneic mouse models, we demonstrate that oncogenic Kras is associated with secretory CAFs and that CXCR2 inhibition promotes activation of fibrotic cells (myofibroblasts) and impact tumors in a mutation-dependent manner.

Understanding the immune landscape and tumor microenvironment of pancreatic cancer to improve immunotherapy

Immunotherapy has revolutionized cancer treatment for several hematologic and solid organ malignancies; however, pancreatic cancer remains unresponsive to conventional immunotherapies. Several characteristics of pancreatic cancer present challenges to successful treatment with immunotherapy, including its aggressive biology, poor immunogenicity, and abundant desmoplastic stroma which can impede effector T cell infiltration and promote an immunosuppressive microenvironment. In this review, we evaluate the current understanding of the immune and stromal landscapes of pancreatic cancer, discuss the successes and failures of stroma-targeted therapies, and highlight how stroma-directed therapies may be synergistic with immunotherapy.

Desmoplastic stromal changes in cutaneous neural granular cell tumors: An under-recognized histopathologic feature of diagnostic and prognostic importance

BACKGROUND

Granular cell tumors (GCTs) are uncommon mucocutaneous and soft tissue neoplasms with distinctive histopathologic appearance but controversial histogenesis. Herein, we report a variant of cutaneous GCT featuring extensive desmoplastic stroma which may result in diagnostic difficulties with mesenchymal proliferations, particularly a dermatofibroma.

METHODS

Following a recent case of GCT with prominent stromal desmoplasia, we reviewed all cases diagnosed as GCT during the past 10 years accessioned at the dermatopathology unit in a tertiary university hospital.

RESULTS

Three additional cases with a similar excessive connective tissue were identified out of a total of 49 GCTs. Cytoplasmic granularity was often subtle and focal, S100 expression was weak, and nuclei had a tendency to show spindling in tumor cells entrapped within the desmoplastic areas. Of note, nuclear spindling is one of the criteria used to diagnose an atypical/malignant GCT.

CONCLUSION

We propose the term "desmoplastic GCT" for these tumors, which not only appropriately addresses the stromal changes but also raises an awareness of GCT being one of the cutaneous tumors which may show stromal desmoplasia. Differential diagnostic difficulties apart, awareness of this phenomenon is important so that desmoplasia and resultant spindling are not linked with potential aggressive behavior.

Development of a Tumor-Responsive Nanopolyplex Targeting Pancreatic Cancer Cells and Stroma

Desmoplasia plays a pivotal role in promoting pancreatic cancer progression and is associated with poor clinical outcome. Targeting the desmoplastic tumor microenvironment in combination with chemotherapy is therefore a promising strategy for pancreatic cancer therapy. Here, we report a novel biodegradable copolymer to codeliver LY2109761 (a TGF-β receptor I/II inhibitor) and CPI-613 (a novel chemotherapy agent) to desmoplastic stroma and tumor cells, respectively, in the tumor microenvironment. Hydrophobic CPI-613 is conjugated to the hydrophilic copolymer via a newly designed MMP-2-responsive linker to form a trigger-responsive nanopolyplex. LY2109761 is hydrophobic and encapsulated into the hydrophobic core of the nanopolyplex. The resulting nanopolyplex is modified with a plectin-1-targeting peptide to enhance the accumulation of the nanopolyplex in pancreatic tumors. The nanopolyplex aims to normalize the stroma by blocking the interaction between tumor cells and pancreatic stellate cells to inhibit the activation of pancreatic stellate cells and subsequently reduce the dense extracellular matrix. Normalized stroma increases the penetration of the nanopolyplex into the tumor. The nanopolyplex shows enhanced accumulation in xenograft pancreatic tumors in a biodistribution study. Moreover, the targeted nanopolyplex markedly inhibits tumor growth in an orthotopic pancreatic cancer mouse model by dual-targeting tumor cells and stroma. Overall, the multifunctional nanopolyplex is a promising platform for pancreatic cancer therapy.

CAF Subpopulations: A New Reservoir of Stromal Targets in Pancreatic Cancer

Cancer-associated fibroblasts (CAFs) are one of the most significant components in the tumour microenvironment (TME), where they can perform several protumourigenic functions. Several studies have recently reported that CAFs are more heterogenous and plastic than was previously thought. As such, there has been a shift in the field to study CAF subpopulations and the emergent functions of these subsets in tumourigenesis. In this review, we explore how different aspects of CAF heterogeneity are defined and how these manifest in multiple cancers, with a focus on pancreatic ductal adenocarcinoma (PDAC). We also discuss therapeutic approaches to selectively target protumourigenic CAF functions, while avoiding normal fibroblasts, providing insight into the future of stromal targeting for the treatment of PDAC and other solid tumours.