Cholangiocarcinoma remains the second most prevalent hepatic neoplasm in the United States with a 5-year survival rate of less than 10%. Currently, no systemic therapy has demonstrated efficacy. Therefore, an urgent need for the identification of molecularly targeted compound(s) remains. The Notch signaling pathway has been shown to be dysregulated in cholangiocarcinoma, exhibiting hyperactivity while also possibly mediating chemotherapeutic resistance. We analyzed the effects of xanthohumol, a prenylated chalcone, on cholangiocarcinoma proliferation utilizing human cholangiocarcinoma cell lines CCLP1, SG-231 and CC-SW-1 while gaining insight into the associated mechanism. Xanthohumol potently reduced cellular proliferation, colony formation, and cell confluency in all three cell lines. Xanthohumol induced cell cycle arrest as well as apoptosis through the reduction of cell cycle regulatory proteins as well as an increase in pro-apoptotic markers (cleaved poly ADP ribose polymerase, cleaved caspase-3) and a decrease in anti-apoptotic markers (X-linked inhibitor of apoptosis and survivin). At the molecular level, xanthohumol reduced Notch1 and AKT expression in a step-wise and time-dependent fashion, with Notch1 reductions preceding AKT. Additionally, xanthohumol reduced cholangiocarcinoma growth in both CCLP-1 and SG-231 derived mice xenografts. In summary, we show that xanthohumol significantly reduced cholangiocarcinoma growth through the Notch1/AKT signaling axis. Furthermore, known pharmacokinetics and bioavailability of XN supports continued development of treatment for cholangiocarcinoma.

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.

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BackgroundFluoropyrimidine with platinum-based chemotherapy has become the standard of care for advanced gastric and gastroesophageal (GEJ) cancer. Trials in colon cancer show that induction chemotherapy followed by maintenance chemotherapy is an efficacious strategy to maximize clinical response while minimizing toxicity. The current retrospective study aims to evaluate the efficacy and tolerability of maintenance versus continuous treatment in advanced GEJ malignancy.MethodsA retrospective analysis of patients with metastatic gastric/GEJ adenocarcinoma treated with fluoropyrimidine and platinum chemotherapy between 2007-2017 was performed. Patients who achieved at least stable disease after initial induction treatment were included. After 16 weeks of induction chemotherapy, patients were categorized into the continuous group if induction chemotherapy was continued and the maintenance group if chemotherapy was switched to maintenance fluoropyrimidine monotherapy or observed off treatment. Endpoints were progression-free survival (PFS), overall survival (OS), and toxicities.ResultsIn total, 90 patients met the criteria, 48 received continuous therapy, and 42 received maintenance. Baseline characteristics were comparable. No difference in PFS (9.9 vs 8.4 months p = .28) or in OS (16.1 vs 21.3 months p = .75) was observed, including after controlling for the best response on induction therapy and other variables. In patients on continuous induction therapy, there was a higher prevalence of grade three neuropathy (42.6% vs 9.8% p = .001) and neutropenic fever (13% vs 0% p =.03).ConclusionsMaintenance therapy following induction fluoropyrimidine and platinum-based therapy is associated with an improved toxicity profile and appears to have comparable efficacy to continuous treatment in metastatic gastric/GEJ cancer.

225 Background: HR deficient (HRD) CRC has improved outcomes following exposure to DNA damaging agent (DDA) (irinotecan, IR; oxaliplatin, OX) compared to HRP CRC. Low expression of wild type (WT) BRCA1 mRNA is associated with prolonged OS in ovarian cancer; however, this finding has not been investigated in CRC or outside of BRCA. Here, we examine the effect of low expression of HR genes in HRP CRC on post-DDA survival. Methods: 12,860 CRC samples were analyzed by NGS (592, NextSeq; WES, NovaSeq) and WTS (NovaSeq) at Caris Life Sciences (Phoenix, AZ). Samples were classified by RNA expression percentiles. Real world OS was extracted from insurance claims and calculated using Kaplan-Meier estimates for molecularly defined cohorts from first of OX or IR to last contact. Results: Post-IR survival was prolonged with low expression of ATM, CHEK2 and PALB2 in WT ATM, PALB2, and CHEK2 WT CRC, respectively (bottom vs. top 10%, bottom vs. top 25%; p<0.05). Notably, low PALB2 expression (bottom 10%) showed a 14.5-month post-IR benefit compared to high PALB2 expression (top 10%) in WT PALB2 CRC (p=0.003). Post-OX survival was not significantly prolonged with low expression of CHEK2 in WT CHEK2 CRC (bottom 10% vs top 10%, bottom 25% vs top 25%) but was with low expression of ATM (+9.7 months, p=0.02) and PALB2 (+5.6 months, p=0.03) in WT ATM and PALB2 CRC, respectively (all bottom 25% vs top 25%). Conclusions: Here we report the first findings to suggest a novel subclass of CRC defined as the low expression of mRNA of non-mutated HRD genes that exhibit sensitivity to DDA. Low expression of WT ATM, CHEK2, and PALB2 correlates with prolonged OS following IR, post-OX survival was prolonged with low expression of ATM and PALB2. Further characterization defining sensitivity of low expressing HRP genes to DDA may help guide treatment considerations in HRP CRC. [Table: see text]