Droplet digital polymerase chain reaction (ddPCR) is a highly sensitive and accurate method for quantification of nucleic acid sequences. We used absolute quantification of mutated v-Ki-ras2 Kirsten rat sarcoma viral oncogene homology gene (KRAS) by ddPCR to investigate the prognostic role of mutated KRAS in patients with KRASmutated lung adenocarcinomas. Pre-treatment plasma samples from 60 patients with stages I-IV KRAS-mutated lung adenocarcinomas were analysed for KRAS mutations. The associations between survival, detectable KRAS mutations in plasma, and the plasma concentration of mutated KRAS were assessed. Overall, 23 of 60 (38%) patients had detectable KRAS mutation in plasma. The percentage of patients with detectable mutation was 8% in stage I, 30% in stage II, 71% in stage III, and 73% in stage IV. Estimated overall median progression-free survival (PFS) and overall survival (OS) were 26.2 months [95% confidence interval (CI) 12.5-39.9] and 50.8 months (95% CI 0-107.3), respectively. Patients with detectable mutations in plasma had significantly worse median PFS compared to patients with undetectable mutation (13.1 versus 70.1 months) and shorter median OS (20.7 versus not reached). High circulating tumour DNA (ctDNA) concentrations of mutated KRAS were significantly associated with shorter PFS [hazard ratio (HR) 1.008, 95% CI 1.004-1.012] and OS (HR 1.007, 95% CI 1.003-1.011). All associations remained statistically significant in multivariable analyses. In conclusion, ddPCR is an accurate and easily feasible technique for quantification of KRAS mutations in ctDNA. The presence of detectable KRAS mutation in plasma at baseline was associated with worse PFS and OS. High concentration of mutated KRAS in ctDNA was an independent negative prognostic factor for both PFS and OS.

Background: due to emerging therapeutics targeting KRAS G12C and previous reports with conflicting results regarding the prognostic impact of KRAS and KRAS G12C in non-small cell lung cancer (NSCLC), we aimed to investigate the frequency of KRAS mutations and their associations with clinical characteristics and outcome. Since mutation subtypes have different preferences for downstream pathways, we also aimed to investigate whether there were differences in outcome according to mutation preference for the Raf, PI3K/Akt, or RalGDS/Ral pathways. Methods: retrospectively, clinicopathological data from 1233 stage I–IV non-squamous NSCLC patients with known KRAS status were reviewed. KRAS’ associations with clinical characteristics were analysed. Progression free survival (PFS) and overall survival (OS) were assessed for the following groups: KRAS wild type (wt) versus mutated, KRAS wt versus KRAS G12C versus KRAS non-G12C, among KRAS mutation subtypes and among mutation subtypes grouped according to preference for downstream pathways. Results: a total of 1117 patients were included; 38% had KRAS mutated tumours, 17% had G12C. Among KRAS mutated, G12C was the most frequent mutation in former/current smokers (45%) and G12D in never smokers (46%). There were no significant differences in survival according to KRAS status, G12C status, among KRAS mutation subtypes or mutation preference for downstream pathways. Conclusion: KRAS status or KRAS mutation subtype did not have any significant influence on PFS or OS.

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(1) Background: Analysis of tumor DNA by next-generation sequencing (NGS) plays various roles in the classification and management of cancer. This study aimed to assess the performance of two similar and large, comprehensive gene panels with a focus on clinically relevant variant detection and tumor mutation burden (TMB) assessment; (2) Methods: DNA from 19 diagnostic small cell lung cancer biopsies and an AcroMetrix™ assessment sample with >500 mutations were sequenced using Oncomine™ Comprehensive Assay Plus (OCAP) on the Ion Torrent platform and TruSight Oncology 500 Assay (TSO500) on the Illumina platform; (3) Results: OCAP and TSO500 achieved comparable NGS quality, such as mean read coverage and mean coverage uniformity. A total of 100% of the variants in the diagnostic samples and 80% of the variants in the AcroMetrix™ assessment sample were detected by both panels, and the panels reported highly similar variant allele frequency. A proportion of 14/19 (74%) samples were classified in the same TMB category; (4) Conclusions: Comparable results were obtained using OCAP and TSO500, suggesting that both panels could be applied to screen patients for enrolment in personalized cancer treatment trials.

Background The low level of circulating tumor DNA (ctDNA) in the blood is a well-known challenge for the application of liquid biopsies in early-stage non-small cell lung cancer (NSCLC) management. Studies of metastatic NSCLC indicate that ctDNA levels are associated with tumor metabolic activity as measured by 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT). This study investigated this association in NSCLC patients considered for potentially curative treatment and explored whether the two methods provide independent prognostic information. Method Patients with stage I-III NSCLC who had routinely undergone an 18F-FDG PET/CT scan and exploratory ctDNA analyses were included. Tumor glucose uptake was measured by maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) from the 18F-FDG PET/CT scans. ctDNA detectability and quantity, using variant allele frequency, were estimated by tumor-informed ctDNA analyses. Results In total, 63 patients (median age 70 years, 60% women, and 90% adenocarcinoma) were included. The tumor glucose uptake (SUVmax, MTV, and TLG) was significantly higher in patients with detectable ctDNA (n = 19, p < 0.001). The ctDNA quantity correlated with MTV (Spearman’s ρ = 0.53, p = 0.021) and TLG (Spearman’s ρ = 0.56, p = 0.013) but not with SUVmax (Spearman’s ρ = 0.034, p = 0.15). ctDNA detection was associated with shorter OS independent of MTV (HR: 2.70, 95% CI: 1.07–6.82, p = 0.035) and TLG (HR: 2.63, 95% CI: 1.06–6.51, p = 0.036). Patients with high tumor glucose uptake and detectable ctDNA had shorter overall survival and progression-free survival than those without detectable ctDNA, though these associations were not statistically significant (p > 0.05). Conclusion There was a positive correlation between plasma ctDNA quantity and MTV and TLG in early-stage NSCLC patients. Despite the correlation, the results indicated that ctDNA detection was a negative prognostic factor independent of MTV and TLG.

Conclusion: Our findings suggest that the unexpected survival of STS and LTS ADK-patients is determined by a concert of clinical and pathological features. Biological characterization of these kind of patients will likely improve the understanding of their unusual course.

Purpose Circulating tumor DNA (ctDNA) can potentially be used to monitor cancer treatment response. In this study, we developed and used a sensitive and selective ultra-deep next-generation sequencing (NGS) approach for detection of ctDNA in lung cancer patients. Method Most studies use fixed gene panels for detection of ctDNA by NGS. Deep sequencing of large target regions is expensive and generates a myriad of variants, which are difficult to interpret. For the purpose of using ctDNA for monitoring, we try to overcome these challenges by sequencing only selected regions where mutations were previously found in the tumor. This method is more sensitive and cost-efficient. In this study, we included about 80 lung cancer patients. Tumor DNA was sequenced with a large gene panel and somatic mutations were identified in each tumor. We then defined the target region according to the tumor mutations and selected primers for constructing NGS libraries. Since the coverage region is small it enables ultra-deep sequencing of several samples simultaneously. We evaluated the lower limit of detection for this method by sequencing a series of artificially constructed samples with known mutant allele frequencies (MAFs). DNA from peripheral blood leucocytes was sequenced in parallel with plasma DNA to exclude variants from clonal hematopoiesis. Preliminary results Using 40 ng as input DNA, which contains approximately 12,000 haploid genomes, we detected mutations down to 0.02% MAF. This corresponds to about 6 mutated copies per mL plasma. Currently, we are applying this method on patient plasma DNA samples. Conclusion We have developed a sensitive method for ctDNA detection, and we will present the results of the lung cancer patient samples. Citation Format: Anine Larsen Ottestad, Elisabeth F. Emdal, Sissel G. Wahl, Bjørn Henning Grønberg, Hong Yan Dai. Ultra-deep next-generation sequencing of selected single genes for detecting circulating tumor DNA in lung cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3099.