Mody, Kabir

AbstractPurpose:To analytically and clinically validate microsatellite instability (MSI) detection using cell-free DNA (cfDNA) sequencing.Experimental Design:Pan-cancer MSI detection using Guardant360 was analytically validated according to established guidelines and clinically validated using 1,145 cfDNA samples for which tissue MSI status based on standard-of-care tissue testing was available. The landscape of cfDNA-based MSI across solid tumor types was investigated in a cohort of 28,459 clinical plasma samples. Clinical outcomes for 16 patients with cfDNA MSI-H gastric cancer treated with immunotherapy were evaluated.Results:cfDNA MSI evaluation was shown to have high specificity, precision, and sensitivity, with a limit of detection of 0.1% tumor content. In evaluable patients, cfDNA testing accurately detected 87% (71/82) of tissue MSI-H and 99.5% of tissue microsatellite stable (863/867) for an overall accuracy of 98.4% (934/949) and a positive predictive value of 95% (71/75). Concordance of cfDNA MSI with tissue PCR and next-generation sequencing was significantly higher than IHC. Prevalence of cfDNA MSI for major cancer types was consistent with those reported for tissue. Finally, robust clinical activity of immunotherapy treatment was seen in patients with advanced gastric cancer positive for MSI by cfDNA, with 63% (10/16) of patients achieving complete or partial remission with sustained clinical benefit.Conclusions:cfDNA-based MSI detection using Guardant360 is highly concordant with tissue-based testing, enabling highly accurate detection of MSI status concurrent with comprehensive genomic profiling and expanding access to immunotherapy for patients with advanced cancer for whom current testing practices are inadequate.See related commentary by Wang and Ajani, p. 6887

e19088 Background: Significant disparities in the stage at diagnosis and survival outcomes exist between various groups diagnosed with hepatocellular carcinoma (HCC) based on sex, race, insurance coverage, and marital status. Previously published data shows disparities more in patients who are African-American, Asian and low income. Little data has been published on factors that influence timeliness to treatment initiation in patients diagnosed with HCC. Methods: Retrospective analysis was performed on 96,586 patients diagnosed with HCC from 2004-2014 using data in the National Cancer Database (NCDB). Time to treatment was divided into two categories: ≤40 days (early, n = 66322) and > 40 days (late, n = 30264). We carried out univariate and multivariate analyses to compare demographic, clinical, treatment, and facility-related factors influencing the timeliness of treatment initiation in HCC. Results: Univariate analysis revealed a significant difference in time to treatment initiation based on age, race, income, insurance status, type of area, geographic region, type of facility, and cancer stage (P < 0.001). Multivariate analysis showed that household income < $30,000/year, Pacific region, urban area of residence, black race, age 70-79 years old or ≥80 years old, academic centers, stage II disease and medicaid insurance were all factors with longer time to treatment initiation. Discussion: HCC is the sixth most common cancer and the second leading cause of cancer mortality worldwide. The 5-year relative survival for localized, regional, and distant stages are 32.6%, 10.8% and 2.4% respectively. In our results we noted significant disparities in time to treatment with respect to various socioeconomic factors. These results are comparable to that reported in other cancer types. Further subgroup analysis of our data shows 2581 patients who received their first treatment after 200 days. In a similar study done in Taiwan, those treated more than 181 days and 61–180 days after diagnosis had a 1.68 and a 1.39 increased risk of death respectively, which were statistically significant. Many factors contribute to delayed treatment, some of which are difficult to circumvent, however where possible efforts should be made to overcome these. Conclusions: Various socioeconomic factors were found to affect the time to treatment initiation in HCC patients. The next step would be to strategically implement policies and practices to address these factors.

580 Background: Though studies indicate that the genomic profiles of ICC and ECC are distinct, the clinical features that differentiate them still remain to be well characterized. The purpose of this study was to further analyze these differences and patient treatment patterns in a multi-center cohort. Methods: A retrospective chart review was performed at 8 institutions on patients (pts) with ICC or ECC diagnosed after June 2009. Data on demographics, risk factors, treatments, pathology and overall survival (OS) were collected. Tumor genotyping results from CLIA-certified tissue assays were analyzed. Fisher’s exact, Wilcoxon rank sum and log-rank tests were used to compare sub-groups. Results: In a database of 737 pts with cholangiocarcinoma, 538(73%) had ICC and 199(27%) had ECC. Pts with ICC more often presented in later stages, had tumors > 5cm at resection (p < 0.0001) and had metastases to the liver, lymph nodes, lung and/or bone (p < 0.01). Pts with ICC more often received liver directed therapy, targeted therapy and multiple lines of systemic therapy and they more often enrolled in a clinical trial (all p < 0.01). Pts with ECC were more likely to be male, undergo surgery, receive adjuvant chemotherapy and/or chemoradiation (all p < 0.05). Mutation profiling performed in 381 (52%) pts (ICC/ECC = 301/80) showed that pts with ICC were more likely to have IDH1 mutations and FGFR2 fusions, whereas pts with ECC were more likely to have KRAS, APC, SMAD4, WNT, TGFb and TP53 mutations (all < 0.05). Factors that did not differ significantly between pts with ICC and ECC include race, rates of primary sclerosing cholangitis, median diagnosis CA19-9 levels and R1 resection rate. Median OS from diagnosis was 18.9 months in ICC and 17.3 months in ECC (p = 0.8471). Conclusions: While pts with ICC and ECC have some similarities in their clinical features, differences in metastases patterns and molecular profiling significantly impact their management such that pts with ICC receive more liver-directed therapy, targeted therapy and more lines of systemic therapy. Further prospective studies are needed as referral patterns to tertiary care centers may have impacted these results.

AbstractAblation is now recommended by international guidelines for the definitive treatment of hepatocellular carcinoma (HCC). Extensive clinical studies have demonstrated outcomes comparable to surgical resection with shorter hospital stays, decreased costs, and improved quality of life. Successful ablation requires complete treatment of both tumor and margin while preserving critical adjacent structures. HCC exhibits highly variable presentations in both anatomic involvement and biology which have significant implications on choice of ablative therapy. There are now abundant ablation modalities and adjunctive techniques which can be used to individualize ablation and maximize curative results. This article provides a patient-centered summary of approaches to HCC ablation in the context of patient performance, hepatic reserve, tumor phenotype and biology, intra- and extrahepatic anatomy, and ablation technology.

Abstract Background Regorafenib at different dosing strategies and TAS-102 are treatment options for refractory metastatic colorectal cancer (mCRC). We aimed to evaluate the comparative effectiveness evidence supporting these different strategies. Materials and Methods We searched different databases for randomized controlled trials evaluating TAS-102 or regorafenib in patients with refractory mCRC who failed prior oxaliplatin, irinotecan, and fluoropyrimidine. Outcomes of interest included overall survival (OS) and progression-free survival (PFS). The overall effect was pooled using the DerSimonian random effects model. We conducted network meta-analysis based on White's multivariate meta-regression to pool evidence from direct and indirect comparisons. Results Six trials at low risk of bias (2,445 patients) were included. Direct comparisons showed that Rego 160 and TAS-102 as monotherapy were superior to best-supportive care (BSC) in terms of PFS (Rego 160: hazard ratio [HR], 0.4; 95% confidence ratio [CI], 0.26–0.63; TAS-102: HR, 0.46 CI, 0.40–0.52) and OS (Rego 160: HR, 0.67; CI, 0.48–0.93; TAS-102: HR, 0.67; CI, 0.57–0.80). Network analysis showed no statistically difference in PFS or OS between Rego 160 and TAS-102. Rego 80+ was superior to BSC in terms of OS (HR, 0.44; CI, 0.23–0.84) and PFS (HR, 0.37; CI, 0.21–0.66). Rego 80+ was associated with statistically nonsignificant improvement in OS and PFS compared with TAS-102 and Rego 160. Conclusion Regorafenib 160 and TAS-102 appear to have similar efficacy. Rego 80+ is shown to be superior to BSC. A trend for improved OS was observed with Rego 80+ versus Rego 160 or TAS 102. Implications for Practice Regorafenib at a dose of 160 mg and TAS-102 appear to have similar efficacy in patients with refractory metastatic colorectal cancer. Regorafenib with a dose escalation strategy is superior to best-supportive care. Given its tolerability and the observed trend in survival benefit compared with regorafenib 160, dose escalation strategy of regorafenib (80+) may be the preferred option in this setting.

e15698 Background: Neuroendocrine tumors (NETs) and carcinomas (NECs) are a diverse group of tumors with an equally diverse biology and clinical behavior. Data on tissue-based genomic profiling of NETs exists, however, there is limited data using circulating tumor DNA (ctDNA) technology. We sought out to characterize NETs via ctDNA to identify genomic alterations. Methods: 27 patients with metastatic NET/NEC with 32 total plasma samples were analyzed using Guardant360 ctDNA assay. Breakdown of NET/NEC by location: 14 pancreatic NET (pNET), 11 NEC, 1 small bowel NET, 1 lung NET. The ctDNA test detects single nucleotide variants in 54-73 genes, copy number amplifications, fusions, and indels in selected genes. Results: Of the 27 patients, 19 (70%) had a detectable genomic alteration. The detectable (non-synonymous) alterations are as follows: TP53 (n = 14, 70%), NF1 (n = 8, 40%), EGFR (n = 5, 25%), BRCA2 (n = 4, 20%), KRAS (n = 4, 20%), ARID1A (n = 3, 15%), CDK6 (n = 3, 15%), ALK (n = 3, 15%), MET (n = 2, 10%), PTEN (n = 2, 10%), BRAF (n = 2, 10%), MTOR (n = 2, 10%) AKT1 (n = 1), BRCA1 (n = 1), CCND2 (n = 1), CCNE1 (n = 1), CTNNB1 (n = 1), ESR1 (n = 1), FGFR2 (n = 1), HRAS (n = 1), IDH1 (n = 1), KIT (n = 1), MYC (n = 1), NOTCH1 (n = 1), NRAS (n = 1), PDGFRA (n = 1), RAF1 (n = 1), RB1 (n = 1), SMAD4 (n = 1), STK11 (n = 1), TSC1 (n = 1), ERBB2 (n = 1), PIK3CA (n = 1). Conclusions: This experience highlights the feasibility of ctDNA to help identify genomic alterations in this patient population. Further studies incorporating ctDNA testing in this patient population are warranted.