A dualistic model of primary anal canal adenocarcinoma with distinct cellular origins, etiologies, inflammatory microenvironments and mutational signatures: implications for personalised medicine.

Primary adenocarcinoma of the anal canal is a rare and aggressive gastrointestinal disease with unclear pathogenesis. Because of its rarity, no clear clinical practice guideline has been defined and a targeted therapeutic armamentarium has yet to be developed. The present article aimed at addressing this information gap by in-depth characterising the anal glandular neoplasms at the histologic, immunologic, genomic and epidemiologic levels. In this multi-institutional study, we first examined the histological features displayed by each collected tumour (n = 74) and analysed their etiological relationship with human papillomavirus (HPV) infection. The intratumoural immune cell subsets (CD4, CD8, Foxp3), the expression of immune checkpoints (PD-1, PD-L1), the defect in mismatch repair proteins and the mutation analysis of multiple clinically relevant genes in the gastrointestinal cancer setting were also determined. Finally, the prognostic significance of each clinicopathological variable was assessed. Phenotypic analysis revealed two region-specific subtypes of anal canal adenocarcinoma. The significant differences in the HPV status, density of tumour-infiltrating lymphocytes, expression of immune checkpoints and mutational profile of several targetable genes further supported the separation of these latter neoplasms into two distinct entities. Importantly, anal gland/transitional-type cancers, which poorly respond to standard treatments, displayed less mutations in downstream effectors of the EGFR signalling pathway (i.e., KRAS and NRAS) and demonstrated a significantly higher expression of the immune inhibitory ligand-receptor pair PD-1/PD-L1 compared to their counterparts arising from the colorectal mucosa. Taken together, the findings reported in the present article reveal, for the first time, that glandular neoplasms of the anal canal arise by HPV-dependent or independent pathways. These etiological differences leads to both individual immune profiles and mutational landscapes that can be targeted for therapeutic benefits

A multiplex SNaPshot assay as a rapid method for detecting KRAS and BRAF mutations in advanced colorectal cancers.

International audienceThe analysis of KRAS mutations has become a prerequisite for anti-epidermal growth factor receptor therapy in patients with metastatic colorectal cancers. KRAS mutations are associated with resistance to treatment by monoclonal antibodies such as cetuximab and panitumumab and thus are correlated with a shorter progression-free survival. BRAF mutations also may play a role in treatment decisions. The widespread use of these targeted therapies has generated the need to develop cost-effective methods for routine KRAS and BRAF analysis. The aim of this study was to compare a multiplex SNaPshot assay with DNA sequencing and high-resolution melting analysis for identifying KRAS codons 12 and 13 and BRAF codon 600 mutations. Thus 110 routinely formalin-fixed and paraffin-embedded tissue blocks were tested by each method. The SNaPshot analysis detected KRAS and BRAF codon 600 mutations in, respectively, 34.5% (n = 38) and 10% (n = 11) of these tissue blocks. These results were confirmed by direct DNA sequencing and by high-resolution melting analysis. The costs and time constraints of each detection method were compared at the same time. In conclusion, our newly designed multiplex SNaPshot assay is a fast, inexpensive, sensitive, and robust technique for molecular diagnostic practices and patient selection