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Abstract PD-1/PD-L1 blockade has so far shown limited survival benefit for high-grade ovarian carcinomas. By using paired samples from the NeoPembrOv randomized phase II trial (NCT03275506), for which primary outcomes are published, and by combining RNA-seq and multiplexed immunofluorescence staining, we explore the impact of NeoAdjuvant ChemoTherapy (NACT) ± Pembrolizumab (P) on the tumor environment, and identify parameters that correlated with response to immunotherapy as a pre-planned exploratory analysis. Indeed, i) combination therapy results in a significant increase in intraepithelial CD8+PD-1+ T cells, ii) combining endothelial and monocyte gene signatures with the CD8B/FOXP3 expression ratio is predictive of response to NACT + P with an area under the curve of 0.93 (95% CI 0.85-1.00) and iii) high CD8B/FOXP3 and high CD8B/ENTPD1 ratios are significantly associated with positive response to NACT + P, while KDR and VEGFR2 expression are associated with resistance. These results indicate that targeting regulatory T cells and endothelial cells, especially VEGFR2+ endothelial cells, could overcome immune resistance of ovarian cancers.

Summary: Background: We apply endoscopic ultrasound-guided fine needle aspiration biopsy to cytopathologically diagnose and sample nucleic acids from primary tumours regardless of the disease stage. Methods: 397 patients with proven pancreatic adenocarcinoma were included and followed up in a multicentre prospective study. DNA and mRNA were extracted from materials of primary tumours obtained by endoscopic ultrasound-guided fine needle aspiration biopsy and analysed using targeted deep sequencing and RNAseq respectively. Findings: The variant allele frequency of the KRAS mutation was used to evaluate the tumour cellularity, ranging from 15 to 20% in all cells, regardless of the tumour stage. The molecular profile of metastatic primary tumours significantly differed from other types of tumours, more frequently having TP53 mutations (p = 0.0002), less frequently having RNF43 mutations, and possessing more basal-like mRNA component (p = 0.001). Molecular markers associated with improved overall survival were: mutations in homologous recombination deficiency genes in patients who received first-line platinum-based chemotherapy (p = 0.025) and wild-type TP53 gene in patients with locally advanced tumours who received radio-chemotherapy (p = 0.01). The GemPred transcriptomic profile was associated with a significantly better overall survival in patients with locally advanced or metastatic pancreatic cancer who received a gemcitabine-based first-line treatment (p = 0.019). Interpretation: The combination of genomic and transcriptomic analyses of primary pancreatic tumours enables us to distinguish metastatic tumours from other tumour types. Our molecular strategy may assist in predicting overall survival outcomes for platinum or gemcitabine-based chemotherapies, as well as radio-chemotherapy. Funding: Institut National Du Cancer (BCB INCa_7294), CHU of Toulouse, Inserm and Ligue Nationale Contre le Cancer (CIT program).

Malignant pleural mesothelioma (MPM) is an aggressive cancer with limited therapeutic options. We evaluated the impact of CDK4/6 inhibition by palbociclib in 28 MPM cell lines including 19 patient‐derived ones, using various approaches including RNA‐sequencing. Palbociclib strongly and durably inhibited the proliferation of 23 cell lines, indicating a unique sensitivity of MPM to CDK4/6 inhibition. When observed, insensitivity to palbociclib was mostly explained by the lack of active T172‐phosphorylated CDK4. This was associated with high p16INK4A (CDKN2A) levels that accompany RB1 defects or inactivation, or (unexpectedly) CCNE1 overexpression in the presence of wild‐type RB1. Prolonged palbociclib treatment irreversibly inhibited proliferation despite re‐induction of cell cycle genes upon drug washout. A senescence‐associated secretory phenotype including various potentially immunogenic components was irreversibly induced. Phosphorylated CDK4 was detected in 80% of 47 MPMs indicating their sensitivity to CDK4/6 inhibitors. Its absence in some highly proliferative MPMs was linked to very high p16 (CDKN2A) expression, which was also observed in public datasets in tumours from short‐survival patients. Our study supports the evaluation of CDK4/6 inhibitors for MPM treatment, in monotherapy or combination therapy.

Abstract Introduction The objective was to determine the added value of comprehensive molecular profile by whole‐exome and RNA sequencing (WES/RNA‐Seq) in advanced and refractory cancer patients who had no molecular‐based treatment recommendation (MBTR) based on a more limited targeted gene panel (TGP) plus array‐based comparative genomic hybridization (aCGH). Materials and Methods In this retrospective analysis, we selected 50 patients previously included in the PROFILER trial (NCT01774409) for which no MBT could be recommended based on a targeted 90‐gene panel and aCGH. For each patient, the frozen tumor sample mirroring the FFPE sample used for TGP/aCGH analysis were processed for WES and RNA‐Seq. Data from TGP/aCGH were reanalyzed, and together with WES/RNA‐Seq, findings were simultaneously discussed at a new molecular tumor board (MTB). Results After exclusion of variants of unknown significance, a total of 167 somatic molecular alterations were identified in 50 patients (median: 3 [1–10]). Out of these 167 relevant molecular alterations, 51 (31%) were common to both TGP/aCGH and WES/RNA‐Seq, 19 (11%) were identified by the TGP/aCGH only and 97 (58%) were identified by WES/RNA‐Seq only, including two fusion transcripts in two patients. A MBTR was provided in 4/50 (8%) patients using the information from TGP/aCGH versus 9/50 (18%) patients using WES/RNA‐Seq findings. Three patients had similar recommendations based on TGP/aCGH and WES/RNA‐Seq. Conclusions In advanced and refractory cancer patients in whom no MBTR was recommended from TGP/aCGH, WES/RNA‐Seq allowed to identify more alterations which may in turn, in a limited fraction of patients, lead to new MBTR.

Abstract Pediatric patients with recurrent and refractory cancers are in most need for new treatments. This study developed patient-derived-xenograft (PDX) models within the European MAPPYACTS cancer precision medicine trial (NCT02613962). To date, 131 PDX models were established following heterotopical and/or orthotopical implantation in immunocompromised mice: 76 sarcomas, 25 other solid tumors, 12 central nervous system tumors, 15 acute leukemias, and 3 lymphomas. PDX establishment rate was 43%. Histology, whole exome and RNA sequencing revealed a high concordance with the primary patient’s tumor profile, human leukocyte-antigen characteristics and specific metabolic pathway signatures. A detailed patient molecular characterization, including specific mutations prioritized in the clinical molecular tumor boards are provided. Ninety models were shared with the IMI2 ITCC Pediatric Preclinical Proof-of-concept Platform (IMI2 ITCC-P4) for further exploitation. This PDX biobank of unique recurrent childhood cancers provides an essential support for basic and translational research and treatments development in advanced pediatric malignancies.

Resistance of advanced hormone‐dependent endometrial carcinoma to endocrine therapy remains a worldwide clinical issue. We recently reported that the combination of Vistusertib (V, mTOR inhibitor) and Anastrozole (A, aromatase inhibitor) improves the progression‐free rate compared to Anastrozole alone. However, a better patient selection based on biomarkers would improve patient outcome. We evaluate for the first time the usage of ribosome biogenesis (RiBi) factors as a source of innovative markers. Using 47 FFPE tumours (A n = 18; V + A n = 29), 32 blood samples (A n = 13; V + A n = 19) and 30 samples of total RNAs (A n = 12; V + A n = 18) from the VICTORIA clinical trial, we observed an association between RiBi‐associated markers and drug activity or prediction of treatment response. NOP10 and NHP2 mRNA levels were significantly higher in non‐responders compared to responders in the Vistusertib + Anastrozole arm (P = 0.0194 and P = 0.0002 respectively; i.e. 8 weeks progression‐free survival as endpoint). This study provides RiBi‐based markers relevant for a better selection of patients with advanced endometrial carcinoma by predicting the response of endocrine therapy combined with mTOR inhibitor.

OBJECTIVE: Most gain of function mutations of tyrosine kinase receptors in human tumours are hemizygous. Gastrointestinal stromal tumours (GIST) with homozygous mutations have a worse prognosis. We aimed to identify genes differentially regulated by hemizygous and heterozygous KIT mutations. MATERIALS AND METHODS: Expression of 94 genes and 384 miRNA was analysed with low density arrays in five NIH3T3 cell lines expressing the full-length human KIT cDNA wild-type (WT), hemizygous KIT mutation with del557-558 (D6) or del564-581 (D54) and heterozygous WT/D6 or WT/D54. Expression of 5 of these genes and 384 miRNA was then analysed in GISTs samples. RESULTS: Unsupervised and supervised hierarchical clustering of the mRNA and miRNA profiles showed that heterozygous mutants clustered with KIT WT expressing cells while hemizygous mutants were distinct. Among hemizygous cells, D6 and D54 expressing cells clustered separately. Most deregulated genes have been reported as potentially implicated in cancer and severals, as ANXA8 and FBN1, are highlighted by both, mRNA and miRNA analyses. MiRNA and mRNA analyses in GISTs samples confirmed that their expressions varied according to the mutation of the alleles. Interestingly, RGS16, a membrane protein of the regulator of G protein family, correlate with the subcellular localization of KIT mutants and might be responsible for regulation of the PI3K/AKT signalling pathway. CONCLUSION: Patterns of mRNA and miRNA expression in cells and tumours depend on heterozygous/hemizygous status of KIT mutations, and deletion/presence of TYR568 & TYR570 residues. Thus each mutation of KIT may drive specific oncogenic pathways.