Utility of Circulating Tumor DNA in the Management of Patients With GI Stromal Tumor: Analysis of 243 Patients.

PURPOSE: GI stromal tumor (GIST) is the most common sarcoma of the GI tract. Management of patients with GIST is determined by KIT, PDGFRA, or other genomic alterations. Tissue-based next-generation sequencing (NGS) analysis is the standard approach for diagnosis, prognosis, and treatment selection. However, circulating tumor DNA (ctDNA)-based NGS is a novel and noninvasive alternative. METHODS: ctDNA sequencing results were evaluated in blood samples from 243 de-identified patients within the Guardant360 database. Under an approved institutional review board protocol, a retrospective analysis was performed on 45 single-institution patients. RESULTS: Of 243 patients, 114 (47%) were women, and the median age was 59 years (range, 17-90 years). Patients with no alterations and variations of uncertain significance were excluded. Of the 162 patients with known pathogenic mutations, KIT was the most common (56%), followed by NF (7%), PDGFRA (6%), PI3KCA (6%), KRAS (5%), and others (6%). Most tumors harbored an actionable KIT or PDGFRA mutation. Our institutional cohort (n = 45) had 16 (35%) KIT exon 11 mutations, 3 (6%) KIT exon 9 mutations, and 1 (2%) PDGFRA mutation detected on ctDNA. Resistance mutations were observed in KIT exon 17 (8 patients), exon 13 (3 patients), and in both (3 patients). Our comparison of ctDNA with tissue NGS revealed a positive predictive value (PPV) of 100%. Failure of concordance was observed in patients with localized or low disease burden. From the time of ctDNA testing, the median overall survival was not reached, whereas the median progression-free survival was 7 months. CONCLUSION: ctDNA provides a rapid, noninvasive analysis of current mutations with a high PPV for patients with metastatic GIST. ctDNA-based testing may help to define the optimal choice of therapy on the basis of resistance mutations and should be studied prospectively.

Blood-Based Next-Generation Sequencing Analysis of Appendiceal Cancers.

BACKGROUND: Appendiceal cancers (ACs) are rare. The genomic landscape of ACs has not been well studied. The aim of this study was to confirm the feasibility of next-generation sequencing (NGS) using circulating tumor DNA (ctDNA) in ACs and characterize common genomic alterations. MATERIALS AND METHODS: Molecular alterations in 372 plasma samples from 303 patients with AC using clinical-grade NGS of ctDNA (Guardant360) across multiple institutions were evaluated. Test detects single nucleotide variants in 54-73 genes, copy number amplifications, fusions, and indels in selected genes. RESULTS: A total of 303 patients with AC were evaluated, of which 169 (56%) were female. Median age was 56.8 (25-83) years. ctDNA NGS testing was performed on 372 plasma samples; 48 patients had testing performed twice, 9 patients had testing performed three times, and 1 patient had testing performed four times. Genomic alterations were defined in 207 (n = 207/372, 55.6%) samples, and 288 alterations were identified excluding variants of uncertain significance and synonymous mutations. Alterations were identified in at least one sample from 184 patients; TP53-associated genes (n = 71, 38.6%), KRAS (n = 33, 17.9%), APC (n = 14, 7.6%), EGFR (n = 12, 6.5%), BRAF (n = 11, 5.9%), NF1 (n = 10, 5.4%), MYC (n = 9, 4.9%), GNAS (n = 8, 4.3%), MET (n = 6, 3.3%), PIK3CA (n = 5, 2.7%), and ATM (n = 5, 2.7%). Other low-frequency but clinically relevant genomic alterations were as follows: AR (n = 4, 2.2%), TERT (n = 4, 2.2%), ERBB2 (n = 4, 2.2%), SMAD4 (n = 3, 1.6%), CDK4 (n = 2, 1.1%), NRAS (n = 2, 1.1%), FGFR1 (n = 2, 1.1%), FGFR2 (n = 2, 1.1%), PTEN (n = 2, 1.1%), RB1 (n = 2, 1.1%), and CDK6, CDKN2A, BRCA1, BRCA2, JAK2, IDH2, MAPK, NTRK1, CDH1, ARID1A, and PDGFRA (n = 1, 0.5%). CONCLUSION: Evaluation of ctDNA is feasible among patients with AC. The frequency of genomic alterations is similar to that previously reported in tissue NGS. Liquid biopsies are not invasive and can provide personalized options for targeted therapies in patients with AC. IMPLICATIONS FOR PRACTICE: The complexity of appendiceal cancer and its unique genomic characteristics suggest that customized combination therapy may be required for many patients. Theoretically, as more oncogenic pathways are discovered and more targeted therapies are approved, customized treatment based on the patient's unique molecular profile will lead to personalized care and improve patient outcomes. Liquid biopsies are noninvasive, cost-effective, and promising methods that provide patients with access to personalized treatment.

Feasibility of circulating tumor DNA testing in hepatocellular carcinoma.

BACKGROUND: Advancement of technologies enabling clinical assessment of circulating tumor DNA (ctDNA) are allowing for assessment of tumor specific genetic alterations in patients. This holds incredible promise for early detection of disease, serial monitoring of tumor heterogeneity, elucidation of therapeutic targets, and evaluation of treatment response and mechanisms of resistance. Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and is often diagnosed late, recurs commonly, and is often diagnosed based upon imaging features alone. A comprehensive evaluation of real-time evaluation of ctDNA in patients with HCC has thus far not been undertaken. METHODS: From January 2015 to February 2018, 35 patients with biliary tract cancer (BTC) at the Mayo Clinic Comprehensive Cancer Center underwent ctDNA testing using a clinically available assay. The majority of samples were tested utilizing the 73-gene panel which includes somatic genomic targets, including complete or critical exon coverage in 30 and 40 genes, respectively; and in some, amplifications, fusions, and indels. RESULTS: A total of 44 samples were collected on these 35 patients, with >70% having stage 3 or 4 disease. Among all samples the median number of alterations per sample, excluding variants of undetermined significance (VUS), was 3.5, with a median allele frequency of 0.65%. A total of 122 unique genetic alterations, excluding VUS or synonymous alterations, were seen. The overall landscape of alterations is described. The top 10 genes altered in this cohort of patients, excluding VUS or synonymous alterations, were TP53 (18%), TERT (14%), CTNNB1 (13%), ARID1A (9%), MYC (5%), BRAF (4%), CCND1 (4%), CDK6 (4%), and MET (4%), and EGFR (3%). CONCLUSIONS: Herein, we describe feasibility of ctDNA testing and results from such testing in HCC patients undergoing ctDNA testing in a real-time clinical context. Patients with these cancers stand to benefit immensely from the use of ctDNA technologies, and concerted efforts at further investigation of such are critically needed.

Feasibility and clinical value of circulating tumor DNA testing in patients with gastric adenocarcinomas.

Gastric cancer is one of the leading causes of cancer worldwide, and this trend appears to be rising. Most patients are diagnosed at an advanced stage and thus prognosis is poor. Liquid biopsy, or circulating tumor DNA (ctDNA) testing, is emerging as a promising prognostic and/or predictive biomarker for patients with various types of malignancies. Its value and utility for patients with gastrointestinal malignancies, particularly gastric cancer is still being explored. There is ongoing research in other tumor types to suggest that ctDNA testing can be potentially used to identify tumor specific genomic alterations, predict tumor mutation burden, as well as help assess clinical response. We report on the feasibility and clinical value of ctDNA testing in patients with gastric cancers in a real time clinical context by reporting data on cohort of patients with gastric cancers (including those with gastroesophageal junction adenocarcinomas) treated at our institution.

Circulating Tumor DNA Profiling of Advanced Biliary Tract Cancers.

PURPOSE: Recent advances in molecular diagnostic technologies have allowed for the evaluation of solid tumor malignancies via noninvasive blood sampling, including circulating tumor DNA (ctDNA) profiling. We sought to characterize the ctDNA genomic alteration landscape in patients with biliary tract cancers (BTCs). PATIENTS AND METHODS: From January 2015 to February 2018, 124 patients with BTC at the Mayo Clinic Comprehensive Cancer Center underwent ctDNA testing using a clinically available assay. The majority of samples (n = 122) were tested using the 73-gene panel that includes somatic genomic targets, including complete or critical exon coverage in 30 and 40 genes, respectively, and in some, amplifications, fusions, and indels. RESULTS: A total of 138 samples were included, with approximately 70% of patients having intrahepatic BTC. All patients had locally advanced or metastatic BTC. Samples with one or more alterations, when variants of unknown significance were excluded, numbered 105 (76%). Each sample contained, on average, three alterations with a median allelic fraction of 0.52%. The overall landscape of alterations is summarized in Figures 1 and 2. After excluding variants of unknown significance, therapeutically relevant alterations were observed in 76 patients (55%), including BRAF mutations, ERBB2 amplifications, FGFR2 fusions, FGFR2 mutations, and IDH1 mutations seen in 21% of patients. A different spectrum of alterations was observed in patients with early-onset BTC (younger than age 50 years) compared with older patients (older than age 50 years). CONCLUSION: Data on ctDNA in BTC is currently limited. Our study, the largest cohort reported to date to our knowledge, demonstrates the feasibility of ctDNA testing in this disease. We provide a foundation upon which the field can continue to grow.

Identifying Levorphanol Ingestion Using Urine Biomarkers in Health Care Patients.

BACKGROUND: Levorphanol is a long-acting opioid analgesic that is an optical isomer of dextrorphan, a metabolite of the over-the-counter cough suppressant dextromethorphan. Providers prescribing levorphanol for pain management may need to assess compliance through urine drug testing, as this agent is subject to abuse. Therefore, it is important to differentiate between dextromethorphan and levorphanol ingestion. OBJECTIVES: This article is the first to report urine concentrations of levorphanol/dextrorphan and 3-hydroxymorphinan in human urine and assesses the need for an enantiomeric analysis to distinguish between dextromethorphan and levorphanol ingestion. STUDY DESIGN: Retrospective data review. METHODS: Medication compliance test results were reviewed for 521 urine samples submitted to Aegis Sciences Corporation between July 2014 and July 2016. Samples were included in this analysis if dextromethorphan or levorphanol testing was requested by the ordering provider. Urine samples were hydrolyzed with beta-glucuronidase and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). An enantiomeric analysis to distinguish levorphanol from dextrorphan and (-)-3-hydroxymorphinan (norlevorphanol) from (+)-3-hydroxymorphinan was not performed. RESULTS: Nineteen urine samples with levorphanol listed as prescribed had median levorphanol/dextrorphan and 3-hydroxymorphinan concentrations of 1,881 ng/mL and 141 ng/mL, respectively. One-quarter of the urine samples with dextromethorphan listed as prescribed did not have any detectable dextromethorphan or 3-methoxymorphinan. LIMITATIONS: An enantiomeric analysis was not utilized with the LC-MS/MS testing method; therefore, levorphanol could not be differentiated from dextrorphan, and (-)-3-hydroxymorphinan could not be differentiated from (+)-3-hydroxymorphinan. The hepatic and renal function for these patients was unknown; however, both could impact the metabolism, distribution, and excretion of levorphanol biomarkers in urine. The dextromethorphan and/or levorphanol dose and timing of last ingestion was also not assessed. CONCLUSIONS: It may be impossible to distinguish between levorphanol and dextromethorphan ingestion based on urine biomarkers, unless dextromethorphan or 3-methoxymorphinan is present or an enantiomeric analysis is performed. Therefore, the potential exists for patients prescribed levorphanol to ingest dextromethorphan and appear compliant with levorphanol therapy. This should prompt clinicians to consider the parameters of their laboratory's testing method when interpreting levorphanol drug test results. KEY WORDS: Levorphanol, dextrorphan, dextromethorphan, 3-hydroxymorphinan, urine testing, urine concentration, drug testing, medication compliance testing.

Urine drug testing results and paired oral fluid comparison from patients enrolled in long-term medication-assisted treatment in Tennessee.

Urine drug testing is recommended for individuals receiving medication-assisted treatment. It provides objective information for practitioners to consider and may serve as a protective factor against drug-related mortality. The primary objective of our study was to describe urine drug testing results for patients undergoing long-term medication-assisted treatment (≥6months). The secondary objective was to provide further evidence to establish oral fluid as a reliable alternative to urine. All subjects (n=639) included in the study were enrolled in one of five treatment centers in the state of Tennessee, and all urine specimens were positive for either methadone or buprenorphine. Nicotine (87%), caffeine (70%), marijuana (15%), alcohol (14%) and gabapentin (10%) were the most prevalent substances identified through urine drug testing. The presence of non-maintenance opioids (prescription and/or heroin) may represent relapse; these drugs were present in 10% of specimens tested. Evidence of illicit drug use (cocaine, heroin, marijuana and/or methamphetamine) was detected in 19% specimens. For 126 of the 639 subjects included in the study, paired oral fluid and urine test results were compared for agreement. Of the total paired urine and oral fluid tests, approximately 7% were positive for a drug in both specimen types and 91% were negative in both, resulting in an overall agreement of 98%. The study demonstrates continued use of illicit and commercially available medications in a medication-assisted treatment population undergoing long-term treatment. The results affirm the reliability of oral fluid as an alternative specimen type for compliance testing in this population.