Tumor mutational burden assessment and standardized bioinformatics approach using custom NGS panels in clinical routine.

BACKGROUND: High tumor mutational burden (TMB) was reported to predict the efficacy of immune checkpoint inhibitors (ICIs). Pembrolizumab, an anti-PD-1, received FDA-approval for the treatment of unresectable/metastatic tumors with high TMB as determined by the FoundationOne®CDx test. It remains to be determined how TMB can also be calculated using other tests. RESULTS: FFPE/frozen tumor samples from various origins were sequenced in the frame of the Institut Curie (IC) Molecular Tumor Board using an in-house next-generation sequencing (NGS) panel. A TMB calculation method was developed at IC (IC algorithm) and compared to the FoundationOne® (FO) algorithm. Using IC algorithm, an optimal 10% variant allele frequency (VAF) cut-off was established for TMB evaluation on FFPE samples, compared to 5% on frozen samples. The median TMB score for MSS/POLE WT tumors was 8.8 mut/Mb versus 45 mut/Mb for MSI/POLE-mutated tumors. When focusing on MSS/POLE WT tumor samples, the highest median TMB scores were observed in lymphoma, lung, endometrial, and cervical cancers. After biological manual curation of these cases, 21% of them could be reclassified as MSI/POLE tumors and considered as "true TMB high." Higher TMB values were obtained using FO algorithm on FFPE samples compared to IC algorithm (40 mut/Mb [10-3927] versus 8.2 mut/Mb [2.5-897], p < 0.001). CONCLUSIONS: We herein propose a TMB calculation method and a bioinformatics tool that is customizable to different NGS panels and sample types. We were not able to retrieve TMB values from FO algorithm using our own algorithm and NGS panel.

Systematic assessment of tumor necrosis at baseline in cervical cancer - An independent factor associated with poor outcome.

Cervical cancer (CC) is a leading challenge in oncology worldwide, with high prevalence and mortality rates in young adults, most prominent in low to middle-income countries with marginal screening facilities. From the prospectively collected BioRAIDS (NCT02428842) cohort of primary squamous CC conducted in 7 European countries, a central pathology review was carried out on 294 patients' tumors. The focus was on identification of tumor-stromal characteristics such as CD8+, CD45+, CD68+ staining cells, PD-L1 expression, tumor infiltrating lymphocytes (TILs) together with the degree of tumor necrosis. Both (FIGO-2018) stage (I-II/III-IV) as well as tumor necrosis were highly significantly associated with Progression-free Survival (PFS); with tumor necrosis scoring as most potent independent factor in a multivariable analysis (p < 0.001). Tumor necrosis can be assessed in the very first diagnostic biopsyand our data suggest that this rapid, simple and cost-effective biomarker, should be routinely assessed prior to treatment decisions.

Intratumoral microbiome is driven by metastatic site and associated with immune histopathological parameters: An ancillary study of the SHIVA clinical trial.

BACKGROUND: Data on the role of the microbiota in cancer have accumulated in recent years, with particular interest in intratumoral bacteria. Previous results have shown that the composition of intratumoral microbiome is different depending on the type of primary tumour and that bacteria from the primary tumour could migrate to metastatic sites. METHODS: Seventy-nine patients with breast, lung, or colorectal cancer and available biopsy samples from lymph node, lung, or liver site, treated in the SHIVA01 trial were analysed. We performed bacterial 16S rRNA gene sequencing on these samples to characterise the intratumoral microbiome. We assessed the association between microbiome composition, clinicopathological characteristics, and outcomes. RESULTS: Microbial richness (Chao1 index), evenness (Shannon index) and beta-diversity (Bray Curtis distance) were associated with biopsy site (p = 0.0001, p = 0.03 and p < 0.0001, respectively) but not with primary tumour type (p = 0.52, p = 0.54 and p = 0.82, respectively). Furthermore, microbial richness was inversely associated with tumour-infiltrating lymphocytes (TILs, p = 0.02), and PD-L1 expression on immune cells (p = 0.03), or assessed by Tumor Proportion Score (TPS, p = 0.02) or Combined Positive Score (CPS, p = 0.04). Beta-diversity was also associated with these parameters (p < 0.05). Patients with lower intratumoral microbiome richness had shorter overall survival (p = 0.03) and progression-free survival (p = 0.02) in multivariate analysis. CONCLUSION: Biopsy site, rather than primary tumour type, was strongly associated with microbiome diversity. Immune histopathological parameters such as PD-L1 expression and TILs were significantly associated with alpha and beta-diversity supporting the cancer-microbiome-immune axis hypothesis.

RIOK2 phosphorylation by RSK promotes synthesis of the human small ribosomal subunit.

Ribosome biogenesis lies at the nexus of various signaling pathways coordinating protein synthesis with cell growth and proliferation. This process is regulated by well-described transcriptional mechanisms, but a growing body of evidence indicates that other levels of regulation exist. Here we show that the Ras/mitogen-activated protein kinase (MAPK) pathway stimulates post-transcriptional stages of human ribosome synthesis. We identify RIOK2, a pre-40S particle assembly factor, as a new target of the MAPK-activated kinase RSK. RIOK2 phosphorylation by RSK stimulates cytoplasmic maturation of late pre-40S particles, which is required for optimal protein synthesis and cell proliferation. RIOK2 phosphorylation facilitates its release from pre-40S particles and its nuclear re-import, prior to completion of small ribosomal subunits. Our results bring a detailed mechanistic link between the Ras/MAPK pathway and the maturation of human pre-40S particles, which opens a hitherto poorly explored area of ribosome biogenesis.

Use of a Lariat Capping Ribozyme to Study Cap Function In Vivo.

A lariat cap is a naturally occurring substitute of a conventional mRNA cap and is found in a particular genomic setting in a few eukaryotic microorganisms. It is installed by the lariat capping ribozyme acting in cis. In principle, any RNA molecule in any organism can be equipped with a lariat cap in vivo when expressed downstream of a lariat capping ribozyme. Lariat capping is thus a versatile tool for studying the importance of the 5' end structure of RNA molecules. In this chapter, we present protocols to validate the presence of the lariat cap and measure the efficiency of in vivo cleavage by the lariat capping ribozyme.

Functional link between DEAH/RHA helicase Prp43 activation and ATP base binding.

The DEAH box helicase Prp43 is a bifunctional enzyme from the DEAH/RHA helicase family required both for the maturation of ribosomes and for lariat intron release during splicing. It interacts with G-patch domain containing proteins which activate the enzymatic activity of Prp43 in vitro by an unknown mechanism. In this work, we show that the activation by G-patch domains is linked to the unique nucleotide binding mode of this helicase family. The base of the ATP molecule is stacked between two residues, R159 of the RecA1 domain (R-motif) and F357 of the RecA2 domain (F-motif). Using Prp43 F357A mutants or pyrimidine nucleotides, we show that the lack of stacking of the nucleotide base to the F-motif decouples the NTPase and helicase activities of Prp43. In contrast the R159A mutant (R-motif) showed reduced ATPase and helicase activities. We show that the Prp43 R-motif mutant induces the same phenotype as the absence of the G-patch protein Gno1, strongly suggesting that the processing defects observed in the absence of Gno1 result from a failure to activate the Prp43 helicase. Overall we propose that the stacking between the R- and F-motifs and the nucleotide base is important for the activity and regulation of this helicase family.