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Fulltext Tumour-Associated Macrophages (TAMs) in Colon Cancer and How to Reeducate Them

Yahaya MAF, Lila MAM, Ismail S, Zainol M, Afizan NARNM

J Immunol Res, 2019;2019:2368249.
PMID: 30931335 DOI: 10.1155/2019/2368249

Tumour-associated macrophage (TAM) serves as the site in which most inflammatory cells coreside. It plays an important role in determining the progression and metastasis of a tumour. The characteristic of TAM is largely dependent on the stimuli present in its tumour microenvironment (TME). Under this environment, however, M2 macrophages are found to be in abundance compared to M1 macrophages which later promote tumour progression. Numerous studies have elucidated the relationship between TAM and the progression of tumour; hence, TAM has now been the subject of interest among researchers for anticancer therapy. This review discusses the role of TAM in colorectal cancer (CRC) and some of the potential candidates that could reeducate TAM to fight against CRC. It is with hope that this review will serve as the foundation in understanding TAM in CRC and helping other researchers to select the most suitable candidate to reeducate TAM that could assist in enhancing the tumouricidal activity of M1 macrophage and eventually repress the development of CRC.

Matched MeSH terms: Tumor Microenvironment/immunology*
In human invasive breast ductal carcinoma, tumor stromal macrophages and tumor nest macrophages have distinct relationships with clinicopathological parameters and tumor angiogenesis

Ch'ng ES, Tuan Sharif SE, Jaafar H

Virchows Arch., 2013 Mar;462(3):257-67.
PMID: 23283409 DOI: 10.1007/s00428-012-1362-4

Tumor-associated macrophages play a crucial role in breast cancer progression and tumor angiogenesis. However, evaluation of tumor-associated macrophages incorporating their histological locations is lacking. The aim of this study was to clarify whether macrophages in tumor stroma and macrophages in tumor cell nests have distinctive properties in relation to pertinent breast cancer clinicopathological parameters and tumor angiogenesis. In 94 human invasive breast ductal carcinomas, tumor-associated macrophages were immunostained with anti-CD68 antibody and counted or graded according to these histological locations. Microvessels were immunostained with anti-CD34 antibody and counted for microvessel density. We found that the presence of tumor stromal and tumor nest macrophages was closely correlated (p = 0.001). Both tumor stromal and tumor nest macrophages were associated with mitotic count (p = 0.001 and p = 0.037, respectively). However, only higher tumor stromal macrophage grades were associated with higher tumor grades (p = 0.004) and negative estrogen receptor status (p = 0.007). Multivariate analysis showed that tumors with a high mitotic count score (score 3 vs. scores 1 and 2) had a higher tumor stromal macrophage density (Grades III and IV) when adjusted for tumor size, tubule formation, and estrogen receptor status (odds ratio 3.41, p = 0.010). The tumor nest macrophage count significantly correlated with the microvessel density (p tumor stromal macrophages and tumor nest macrophages residing in different tumor microenvironments have distinctive roles.

Matched MeSH terms: Tumor Microenvironment/immunology
Fulltext The molecular landscape of Asian breast cancers reveals clinically relevant population-specific differences

Pan JW, Zabidi MMA, Ng PS, Meng MY, Hasan SN, Sandey B, et al.

Nat Commun, 2020 Dec 22;11(1):6433.
PMID: 33353943 DOI: 10.1038/s41467-020-20173-5

Molecular profiling of breast cancer has enabled the development of more robust molecular prognostic signatures and therapeutic options for breast cancer patients. However, non-Caucasian populations remain understudied. Here, we present the mutational, transcriptional, and copy number profiles of 560 Malaysian breast tumours and a comparative analysis of breast cancers arising in Asian and Caucasian women. Compared to breast tumours in Caucasian women, we show an increased prevalence of HER2-enriched molecular subtypes and higher prevalence of TP53 somatic mutations in ER+ Asian breast tumours. We also observe elevated immune scores in Asian breast tumours, suggesting potential clinical response to immune checkpoint inhibitors. Whilst HER2-subtype and enriched immune score are associated with improved survival, presence of TP53 somatic mutations is associated with poorer survival in ER+ tumours. Taken together, these population differences unveil opportunities to improve the understanding of this disease and lay the foundation for precision medicine in different populations.

Matched MeSH terms: Tumor Microenvironment/immunology
Fulltext Association of BRCA1- and BRCA2-deficiency with mutation burden, expression of PD-L1/PD-1, immune infiltrates, and T cell-inflamed signature in breast cancer

Wen WX, Leong CO

PLoS One, 2019;14(4):e0215381.
PMID: 31022191 DOI: 10.1371/journal.pone.0215381

Immune checkpoint inhibitors have demonstrated effective anti-tumour response in cancer types with high mutation burden (e.g. melanoma) and in subset of cancers with features of genomic instability (e.g. mismatch-repair deficiency). One possible explanation for this effect is the increased expression of immune checkpoint molecules and pre-existing adaptive immune response in these cancers. Given that BRCA1 and BRCA2 are integral in maintaining genomic integrity, we hypothesise that the inactivation of these genes may give rise to breast cancers with such immunogenic phenotype. Therefore, using two large series of publicly available breast cancer datasets, namely that from The Cancer Genome Atlas and Wellcome Trust Institute, we sought to investigate the association between BRCA1- and BRCA2-deficiency with features of genomic instability, expression of PD-L1 and PD-1, landscape of inferred tumour-infiltrating immune cells, and T-cell inflamed signature in breast cancers. Here, we report that BRCA1 and BRCA2-deficient breast cancers were associated with features of genomic instability including increased mutation burden. Interestingly, BRCA1-, but not BRCA2-, deficient breast cancers were associated with increased expression of PD-L1 and PD-1, higher abundance of tumour-infiltrating immune cells, and enrichment of T cell-inflamed signature. The differences in immunophenotype between BRCA1- and BRCA2-deficient breast cancers can be attributed, in part, to PTEN gene mutation. Therefore, features of genomic instability such as that mediated by BRCA1- and BRCA2- deficiency in breast cancer were necessary, but not always sufficient, for yielding T cell-inflamed tumour microenvironment, and by extension, predicting clinical benefit from immunotherapy.

Matched MeSH terms: Tumor Microenvironment/immunology
Fulltext Therapeutic challenges and current immunomodulatory strategies in targeting the immunosuppressive pancreatic tumor microenvironment

Looi CK, Chung FF, Leong CO, Wong SF, Rosli R, Mai CW

J Exp Clin Cancer Res, 2019 Apr 15;38(1):162.
PMID: 30987642 DOI: 10.1186/s13046-019-1153-8

BACKGROUND: Pancreatic cancer is one of the most lethal type of cancers, with an overall five-year survival rate of less than 5%. It is usually diagnosed at an advanced stage with limited therapeutic options. To date, no effective treatment options have demonstrated long-term benefits in advanced pancreatic cancer patients. Compared with other cancers, pancreatic cancer exhibits remarkable resistance to conventional therapy and possesses a highly immunosuppressive tumor microenvironment (TME).
MAIN BODY: In this review, we summarized the evidence and unique properties of TME in pancreatic cancer that may contribute to its resistance towards immunotherapies as well as strategies to overcome those barriers. We reviewed the current strategies and future perspectives of combination therapies that (1) promote T cell priming through tumor associated antigen presentation; (2) inhibit tumor immunosuppressive environment; and (3) break-down the desmoplastic barrier which improves tumor infiltrating lymphocytes entry into the TME.
CONCLUSIONS: It is imperative for clinicians and scientists to understand tumor immunology, identify novel biomarkers, and optimize the position of immunotherapy in therapeutic sequence, in order to improve pancreatic cancer clinical trial outcomes. Our collaborative efforts in targeting pancreatic TME will be the mainstay of achieving better clinical prognosis among pancreatic cancer patients. Ultimately, pancreatic cancer will be a treatable medical condition instead of a death sentence for a patient.

Matched MeSH terms: Tumor Microenvironment/immunology*