The local immunological microenvironment in colorectal cancer as a prognostic factor for treatment decisions in the clinic: The way ahead

Sequential metastases of colorectal cancer: Immunophenotypes and spatial distributions of infiltrating immune cells in relation to time and treatments

The role of the immune system in the course of colorectal cancer has been elucidated in the last decade. While quantification of immune cell infiltrates within the resected specimen at diagnosis has a clear power to estimate the prognosis of the patient, the role of infiltrating immune cells within the metastatic situation and especially within the metastatic lesion itself requires further detailed analyses. Recent analyses of infiltrates in colorectal cancer liver metastases revealed a role for the infiltrate density not only for prognosis but also in the prediction of treatment response. This not only broadens the view on these infiltrates and indicates a systematic role of the local immunological microenvironment, but also raises the question how these infiltrates change during repeated courses of treatment (i.e., resection, chemotherapy, etc.). To address this question, sequential lung or sequential liver metastases of colorectal cancer patients were analyzed using whole slide image quantification after immunohistochemical staining against CD3, CD8, FOXP3, CD68 and Granzyme B. The clinical data and interventions were associated with each individual patient and the metastatic lesions. The resulting cell densities reveal a heterogeneous profile: after successful treatment of a metastatic lesion, the recurrent lesion can still have the same immunophenotype with similar cell distributions. In a situation of a favorable immune cell profile, this profile can return and apparently convey a similar favorable course throughout the disease. But also the opposite was found: the recurrent metastatic lesion could have a different profile with alterations in specific immune cell subsets over time. Further analyses are required to elucidate the different patterns and their associations to the treatment, the tumor cell phenotype and other dynamic factors. However, it is clear from this data however, that there is an immune cell plasticity that needs to be analyzed for individual patients.

The Unmet Needs of the Diagnosis, Staging, and Treatment of Gastrointestinal Tumors

New scientific insights in cancer biology and immunobiology have changed the clinical practice of medical oncology in recent years. The molecular stratification of solid tumors has led to improved clinical outcomes and is a key part in the diagnostic workup. Beyond mutational spectra (like Rat sarcoma [RAS] mutations or tumor mutational burden), the investigation of the immunological microenvironment has attracted more efforts. Especially as immunotherapies have changed the standard treatment for some solid tumors dramatically and have become an important part of routine oncology, also for gastrointestinal tumors. Still only a subgroup of patients benefits from immunotherapy in gastrointestinal tumors with prominent examples from colorectal, pancreatic or gastric cancer. Not only microsatellite instability as a marker for response to immunotherapy has shown its utility, there plenty of other approaches currently being investigated to better stratify and understand the microenvironment. But these insights have not translated into clinical utility. Reasons for this are limited technical capabilities for stratification and for coping with heterogeneity of tumor cells and the microenvironment as such. So the situation for gastrointestinal tumors has shown mainly progress for a subgroup of immunotherapy-receptive tumors (eg, microsatellite instability), but advances for the remaining majority have been in the area of stratification and combinatorial therapies, including approaches without chemotherapy. Molecular stratification (eg, B-Rapidly Accelerated Fibrosarcoma [BRAF] V600E mutation in colorectal cancer or NRG1 fusions in Kirsten-rat sarcoma (KRAS) Wild-Type Pancreatic Cancer) has clearly improved the possibilities for directed therapies, but there is a plethora of clinical situations where further developments are needed to improve patient care. Finding these areas and identifying the technical approach to unravel the complexities is the next decisive step. Here the recent advances are summarized and an outlook on possible diagnostic and treatment options in areas of unmet need is given with the context of new molecular imaging possibilities and cutting edge advances in nuclear medicine.

Microfluidics-assisted multiplexed biomarker detection for in situ mapping of immune cells in tumor sections

Because of the close interaction between tumors and the immune system, immunotherapies are nowadays considered as the most promising treatment against cancer. In order to define the diagnosis and the subsequent therapy, crucial information about the immune cells at the tumor site is needed. Indeed, different types or activation status of cells may be indicative for specific and personalized treatments. Here, we present a quantitative method to identify ten different immuno-markers in the same tumor cut section, thereby saving precious samples and enabling correlative analysis on several cell families and their activation status in a tumor microenvironment context. We designed and fabricated a microfluidic chip with optimal thermomechanical and optical properties for fast delivery of reagents on tissue slides and for fully automatic imaging by integration with an optical microscope. The multiplexing capability of the system is enabled by an optimized cyclic immunofluorescence protocol, with which we demonstrated quantitative sequential immunostaining of up to ten biomarkers on the same tissue section. Furthermore, we developed high-quality image-processing algorithms to map each cell in the entire tissue. As proof-of-concept analyses, we identified coexpression and colocalization patterns of biomarkers to classify the immune cells and their activation status. Thanks to the quantitativeness and the automation of both the experimental and analytical methods, we believe that this multiplexing approach will meet the increasing clinical need of personalized diagnostics and therapy in cancer pathology.

Non-nuclear AR Signaling in Prostate Cancer

Despite the key role played by androgen receptor (AR) in tumor cell aggressiveness and prostate cancer (PCa) progression, its function in the tumor microenvironment (TME) is still controversial. Increasing studies highlight the crucial role played by TME modulation in treatment outcome and tumor cell spreading. In this context, targeting specific constituents of the TME could be considered an alternative approach to classic treatments directed against cancer cells. Currently, androgen deprivation therapy (ADT) is a routinely adopted strategy in the management of PCa, with initial success, and consecutive fail. A possible justification to this is the fact that ADT aims to target all the transcription/translation-related activities of AR, which are typical of tumor epithelial cells. Less is still known about side effects of ADT on TME. Cancer Associated Fibroblasts (CAFs), for example, express a classic AR, mostly confined in the extra-nuclear portion of the cell. In CAFs ADT exerts a plethora of non-transcriptional effects, depending by the protein partner linked to AR, leading to cell migration, proliferation, and differentiation. In recent years, substantial progress in the structure-function relationships of AR, identification of its binding partners and function of protein complexes including AR have improved our knowledge of its signaling axis. Important AR non-genomic effects and lots of its cytoplasmatic binding partners have been described, pointing out a fine control of AR non-genomic pathways. Accordingly, new AR inhibitors have been designed and are currently under investigation. Prompt development of new approaches to target AR or block recruitment of its signaling effectors, or co-activators, is urgently needed. The present review takes an in-depth look at current literature, furnishing an exhaustive state-of-the-art overview of the non-genomic role of AR in PCa, with particular emphasis on its involvement in TME biology.

Androgen receptor moonlighting in the prostate cancer microenvironment

Androgen receptor (AR) signaling is vital for the normal development of the prostate and is critically involved in prostate cancer (PCa). AR is not only found in epithelial prostate cells but is also expressed in various cells in the PCa-associated stroma, which constitute the tumor microenvironment (TME). In the TME, AR is expressed in fibroblasts, macrophages, lymphocytes and neutrophils. AR expression in the TME was shown to be decreased in higher-grade and metastatic PCa, suggesting that stromal AR plays a protective role against PCa progression. With that, the functionality of AR in stromal cells appears to deviate from the receptor's classical function as described in PCa cells. However, the biological action of AR in these cells and its effect on cancer progression remains to be fully understood. Here, we systematically review the pathological, genomic and biological literature on AR actions in various subsets of prostate stromal cells and aim to better understand the consequences of AR signaling in the TME in relation to PCa development and progression.