Purpose: KRAS mutation (MT) is a major oncogenic driver in PDAC. A small subset of PDACs harbor KRAS-wild-type (WT). We aim to characterize the molecular profiles of KRAS-WT PDAC to uncover new pathogenic drivers and offer targeted treatments. Experimental Design: Tumor tissue obtained from surgical or biopsy material was subjected to next-generation DNA/RNA sequencing, microsatellite-instability (MSI) and mismatch-repair (MMR) status determination. Results: Of the 2,483 patients (male 53.7%, median-age 66 years) studied, 266 tumors (10.7%) were KRAS-WT. The most frequently mutated gene in KRAS-WT-PDAC was TP53 (44.5%), followed by BRAF (13.0%) . Multiple mutations within the DNA-damage-repair (BRCA2, ATM, BAP1, RAD50, FANCE, PALB2), chromatin-remodeling (ARID1A, PBRM1, ARID2, KMT2D, KMT2C, SMARCA4, SETD2), and cell-cycle-control pathways (CDKN2A, CCND1, CCNE1) were detected frequently. There was no statistically-significant difference in PDL1-expression between KRAS-WT (15.8%) and MT (17%) tumors. However, KRAS-WT-PDAC were more likely to be MSI-high (4.7% vs 0.7%; p<0.05), TMB-high (4.5% vs 1%; p<0.05), and exhibit increased infiltration of CD8+ T-cells, NK-cells and myeloid dendritic cells. KRAS-WT-PDACs exhibited gene fusions of BRAF (6.6%), FGFR2 (5.2%), ALK (2.6%), RET (1.3%) and NRG1 (1.3%), as well as amplification of FGF3 (3%), ERBB2 (2.2%), FGFR3 (1.8%), NTRK (1.8%) and MET (1.3%). Real-world evidence reveals a survival advantage of KRAS-WT patients in overall cohorts as well as in patients treated with gemcitabine/nab-paclitaxel or 5FU/oxaliplatin. Conclusions: KRAS-WT PDAC represents 10.7% of PDAC and is enriched with targetable alterations, including immuno-oncologic markers. Identification of KRAS-WT patients in clinical practice may expand therapeutic options in a clinically meaningful manner.

The RASopathies are a group of genetic disorders that result from germline pathogenic variants affecting RAS‐mitogen activated protein kinase (MAPK) pathway genes. RASopathies share RAS/MAPK pathway dysregulation and share phenotypic manifestations affecting numerous organ systems, causing lifelong and at times life‐limiting medical complications. RASopathies may benefit from precision medicine approaches. For this reason, the Sixth International RASopathies Symposium focused on exploring precision medicine. This meeting brought together basic science researchers, clinicians, clinician scientists, patient advocates, and representatives from pharmaceutical companies and the National Institutes of Health. Novel RASopathy genes, variants, and animal models were discussed in the context of medication trials and drug development. Attempts to define and measure meaningful endpoints for treatment trials were discussed, as was drug availability to patients after trial completion.

Purpose: Gene fusions involving R-spondin (RSPOfp) and RNF43 mutations have been shown to drive Wnt-dependent tumor initiation in colorectal cancer (CRC). Herein, we aimed to characterize the molecular features of RSPOfp/RNF43 mutated (mut) compared to wildtype CRCs to gain insights into potential rationales for therapeutic strategies. Experimental Design: A discovery cohort was classified for RSPOfp/RNF43 status using DNA/RNA sequencing and immunohistochemistry. An independent cohort was used to validate our findings. Results: The discovery cohort consisted of 7,245 CRC samples. RSPOfp and RNF43 mutations were detected in 1.3% (n=94) and 6.1% (n=443) of cases. We found 5 RSPO fusion events that had not previously been reported (e.g. IFNGR1-RSPO3). RNF43-mut tumors were associated with right-sided primary tumors. No RSPOfp tumors had RNF43 mutations. In comparison to wildtype CRCs, RSPOfp tumors were characterized by a higher frequency of BRAF, BMPR1A and SMAD4 mutations. APC mutations were observed in only a minority of RSPOfp-positive compared to wildtype cases (4.4 vs. 81.4%). Regarding RNF43 mutations, a higher rate of KMT2D and BRAF mutations were detectable compared to wildtype samples. While RNF43 mutations were associated with a microsatellite instability (MSI-H)/mismatch repair deficiency (dMMR) phenotype (64.3%), and a TMB {greater than or equal to}10 mt/Mb (65.8%), RSPOfp was not associated with MSI-H/dMMR. The validation cohort replicated our genetic findings. Conclusions: This is the largest series of RSPOfp/RNF43-mut CRCs reported to date. Comprehensive molecular analyses asserted the unique molecular landscape associated with RSPO/RNF43 and suggested potential alternative strategies to overcome the low clinical impact of Wnt-targeted agents and immunotherapy.

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a malignant biphasic neoplasm of the thyroid or neck with propensity for late metastasis. Unlike synovial sarcoma, its main morphologic mimic, SETTLE lacks synovial sarcomaassociated translocations. A single case of SETTLE has shown a KRAS mutation but to date no comprehensive next generation sequencing studies of this rare neoplasm have been undertaken. Herein, we subjected 5 well defined cases of SETTLE to direct sequence analysis of 592 genes and fusion gene analysis of 52 genes frequently rearranged in human cancers. We identified one case with two pathogenic variants in the KMT2D gene, one being in an intron splice site (c.674-1A>G) and the other being a frameshift variant (p.M2829fs). This same case also had a pathogenic nonsense variant in the KMT2C gene (p.R1237*). A second case of SETTLE carried a pathogenic NRAS missense variant, Q61R. No other molecular alterations, microsatellite instability, gene fusions or amplifications were identified.