Abstract 5515
Background
Werner syndrome gene (WRN) encodes a DNA helicase with an exonuclease activity that contributes to DNA repair. In cancer, WRN mutations lead to genomic instability. It is known that WRN is necessary to sustain in-vivo growth of cancers cells with microsatellite instability (MSI), including CRC. WRN is a very promising new target especially in cancers with MSI. There is still a lack of knowledge about the frequency of WRN alterations and their association with immunological and molecular phenotypes.
Methods
Tumour samples from 6854 CRC patients were analyzed using NGS (NextSEQ on 592 genes), in-situ hybridization and immunohistochemistry (Caris Life Sciences, Phoenix, AZ, USA). Tumour mutational burden (TMB) was calculated based on somatic non-synonymous missense mutations, and MSI was evaluated by NGS of known MSI loci.
Results
WRN mutations (WRN-mut) were observed in 80 of 6854 samples (1.2%). A higher prevalence of WRN-mut was detected in right- compared to left-sided CRC (2.4% vs 0.7%, p<.0001). In WRN-mut (MT) CRC, TMB (43 vs. 8.6 mutations/megabase [mut/MB], p<.0001) and PD-L1 expression (13% vs 4%, p<.0001) were higher compared to WRN wild-type (WT). A higher frequency of MSI-H was seen in cancers harboring WRN-mut (56% vs 7%, p<.0001). Also, WRN-mut was associated with a higher TMB in both MSI-H subgroup of tumors (54 vs 40 mut/MB, p=.03) and MSS subgroup (43 vs 8.6 mut/MB, p<.0001). Several differences between WRN-mut and WRN-WT CRC was observed, including TP53 (47% vs 73%), KRAS (34% vs 49%), APC (56% vs 73%), BRAF (26% vs 9%), ASXL1 (25% vs 4%), ERBB2 (9% vs 2%), BRCA1 (8% vs 1%), BRCA2 (15% vs 2%), CDK12 (10% vs 1%), (p<.01 for all). Copy number alterations (CNA) of CDX2 were seen only in WRN-WT tumours (6.4% vs 1%, p=.026) and CNAs seen more frequently in WRN-mut tumours included CD274, CALR, CRTC1, ELL, JAK3, KEAP1, LYL1, MEF2B (p<.01).
Conclusions
This is the largest profiling study to investigate the molecular and immunological landscape of WRN-mut CRCs. We show the high prevalence of MSI in WRN-mut tumours and their association with higher TMB and PD-L1 expression. Furthermore, it revealed that WRN-mut CRC is characterized by a distinct genetic profile. Our data might serve to tailor treatment in WRN-mut CRC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5063 - Does Nutritional Status Affect Treatment Tolarability, Response and Survival in Metastatic Gastric Cancer Patients? Results of Prospective Multicenter Study
Presenter: Senem Karabulut
Session: Poster Display session 2
Resources:
Abstract
2717 - Ramucirumab use in patients with Advanced Gastric Cancer (AGC) or gastro-oesophageal junction (GEJ) adenocarcinoma in Spain: RAMIS observational study
Presenter: Federico Longo Munoz
Session: Poster Display session 2
Resources:
Abstract
3187 - Gastrectomy plus chemotherapy versus chemotherapy alone for advanced gastric cancer with a single non-curable factor: Exploratory analysis in the patients who were enrolled in JCOG0705/KGCA01 phase III trial (REGATTA) and could continue chemotherapy
Presenter: Takaki Yoshikawa
Session: Poster Display session 2
Resources:
Abstract
4765 - A prospective observational study on the optimal maintenance strategy in HER2-positive advanced gastric cancer treated with trastuzumab based therapy
Presenter: Qian Li
Session: Poster Display session 2
Resources:
Abstract
3500 - Randomised phase 2 trial of first-line docetaxel, carboplatin, capecitabine (CTX) and epirubicin, oxaliplatin, capecitabine (EOX) in advanced esophagogastric adenocarcinoma (SEED)
Presenter: Peter Petersen
Session: Poster Display session 2
Resources:
Abstract
5197 - Ramucirumab in the treatment of refractory metastatic gastric cancer: results from the RamSelGa trial.
Presenter: Alexey Tryakin
Session: Poster Display session 2
Resources:
Abstract
2011 - Regorafenib in combination with Paclitaxel for beyond first-line treatment of advanced esophagogastric cancer (REPEAT): a phase Ib trial with expansion cohort
Presenter: Mohammed Khurshed
Session: Poster Display session 2
Resources:
Abstract
2117 - The relationship between the survival and fixed dosing of S-1 in advanced gastric cancer patients by pooled analysis using individual data from four Japanese randomized phase III trials
Presenter: Wataru Ichikawa
Session: Poster Display session 2
Resources:
Abstract
2669 - A Phase 1b Study of Oraxol in Combination with Ramucirumab in Patients with Gastric or Esophageal Cancers who failed previous chemotherapy
Presenter: Ming Huang Chen
Session: Poster Display session 2
Resources:
Abstract
3240 - Efficacy and safety of trifluridine/tipiracil (FTD/TPI) in European patients with heavily pretreated metastatic gastric cancer (mGC): an analysis of the TAGS study
Presenter: Maria Alsina
Session: Poster Display session 2
Resources:
Abstract