Citations

e15616 Background: Cholangiocarcinoma (CCA) is a progressively fatal disease with an annual incidence of 1-2 cases per 100,000 people in the USA. Complete surgical resection is the only curative option for CCA. However, the majority of patients (pts) have advanced disease at diagnosis, and those undergoing resection often develop local or distant recurrence. Gemcitabine and Cisplatin remains the only standard chemotherapeutic regimen for advanced CCA. Alternative and improved therapies are critically needed. Gemcitabine/nab-Paclitaxel (GA) is a regimen that has become standard therapy in advanced pancreatic cancer (PDAC). Given the morphologic and histologic similarities between PDAC and CCA, this regimen has been used in advanced CCA, but no data exists regarding its efficacy in this disease. The goal of our study is to evaluate the Mayo Clinic experience with GA for the treatment of metastatic CCA. Methods: We retrospectively analyzed records from adult pts at Mayo Clinic with metastatic cholangiocarcinoma who received at least 2 cycles of GA. Our aims were to assess the progression-free survival (PFS), overall survival (OS) and disease response. Results: We analyzed 9 pts, 3 male and 6 female. The median age at diagnosis was 50 years (range 41-64). Six pts had metastatic disease at diagnosis while 3 underwent surgery with subsequent distant disease recurrence. Pts received a median of 2 lines (range 0-5) of systemic therapy prior to receiving GA, and a median of 2 cycles (range 2-15) of GA. At the time of our analysis, 4 of the 9 pts (44%) had died. The median OS from initiation of GA was 7.3 months (95% CI 1.7- 12.9) and median PFS from initiation of GA was 4.7 months (95% CI 0.48-8.9). The best overall responses using RECIST criteria were: partial response in 1 (11%), stable disease in 5 (55%) and disease progression in 3 (33%) pts. One pt remained on therapy 14.9 months after initiating GA. Conclusions: In our study, the combination of gemcitabine and nab-paclitaxel has demonstrated similar OS and PFS as other systemic therapies. To the best of our knowledge, this is the first report of this regimen in CCA. Ongoing, prospective trials are currently evaluating this regimen in advanced CCA.

Abstract The liver is the most common site of metastasis in pancreatic ductal adenocarcinoma (PDAC). This metastatic tropism is dependent, at least in part, on the formation of a “pro-metastatic” niche that supports tumor cell seeding and colonization in the liver. However, mechanisms that direct the formation of this niche remain poorly understood. We show using the LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre (KPC) model of PDAC that pancreatic tumor development enhances the susceptibility of the liver to metastatic seeding by inducing recruitment of F4/80+ and Ly6G+ myeloid cells and fibrosis within the liver. 3' mRNA sequencing (QuantSeq) on RNA isolated from the liver of KPC mice versus control PC mice revealed that the liver produces a specific set of myeloid chemoattractants, particularly serum amyloid A1 and A2 (SAA1/2), early during PDAC development. In addition, gene set enrichment analysis (GSEA) on genes upregulated in the liver of KPC mice demonstrated a significant enrichment of the interleukin 6 (IL-6)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway. Consistent with this finding, phosphorylation of STAT3 was detected in 20-30% of F4/80+ myeloid cells and 80-90% of hepatocytes. A requirement for IL-6/STAT3 signaling in the formation of a pro-metastatic niche was determined by comparing the metastatic potential of wild type mice, Il-6 knockout (Il-6-/-) mice, and mice treated with anti-IL-6 receptor (IL-6R) antibody after orthotopic implantation of KPC-derived PDAC cells. Compared to wild type mice, the liver of Il-6-/- mice and mice treated with anti-IL-6R antibody was less susceptible to metastatic seeding and showed significantly less accumulation of myeloid cells, fibrosis, and production of SAA1/2 in the liver. We obtained similar results with mice that lack Stat3 specifically in hepatocytes (Stat3flox/flox Alb-Cre), demonstrating that IL-6/STAT3 signaling in hepatocytes is necessary for the formation of a pro-metastatic niche in the liver. Further, using Saa1/2 double knockout (Saa-/-) mice, we found that SAA1/2 production by hepatocytes was required for formation of the pro-metastatic niche in the liver and increased susceptibility to metastatic seeding. Patients with a history of liver metastasis also showed higher levels of SAA1/2 in the plasma compared to normal donors, and SAA overexpression was detected in hepatocytes in liver biopsy samples collected from PDAC patients. Collectively, our study reveals a novel role for hepatocytes in directing the formation of a pro-metastatic niche in the liver during PDAC development and identifies IL-6/STAT3/SAA1/2 signaling as a promising therapeutic target for prevention of metastasis in PDAC. Citation Format: Jae W. Lee, Stacy K. Thomas, Chad A. Komar, Whitney L. Gladney, Xia Hua, Dong Xin, Abraham Shaked, Mitesh J. Borad, Ramesh K. Ramanathan, Ailing Ji, Nancy R. Webb, Maria C. de Beer, Frederick C. de Beer, Paige M. Porrett, Gregory L. Beatty. IL-6/STAT3 activation in hepatocytes drives pro-metastatic niche formation in the liver [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1102.

About 15% of intrahepatic cholangiocarcinomas (ICCs) express constitutively active fibroblast growth factor receptor 2 (FGFR2) fusion proteins (FFs) generated by chromosomal translocations. FFs have been nominated as oncogenic drivers because administration of FGFR tyrosine kinase inhibitors (F‐TKIs) can elicit meaningful objective clinical responses in patients carrying FF‐positive ICC. Thus, optimization of FF targeting is a pressing clinical need. Herein, we report that three different FFs, previously isolated from ICC samples, are heat shock protein 90 (HSP90) clients and undergo rapid degradation upon HSP90 pharmacological blockade by the clinically advanced HSP90 inhibitor ganetespib. Combining catalytic suppression by the F‐TKI BGJ398 with HSP90 blockade by ganetespib suppressed FGFR2‐TACC3 (transforming acidic coiled‐coil containing protein 3) signaling in cultured cells more effectively than either BGJ398 or ganetespib in isolation. The BGJ398 + ganetespib combo was also superior to single agents when tested in mice carrying subcutaneous tumors generated by transplantation of FGFR2‐TACC3 NIH3T3 transformants. Of note, FF mutants known to enforce clinical resistance to BGJ398 in ICC patients retained full sensitivity to ganetespib in cultured cells. Conclusion: Our data provide a proof of principle that upfront treatment with the BGJ398 + ganetespib combo improves therapeutic targeting of FGFR2 fusions in an experimental setting, which may be relevant to precision medicine approaches to FF‐driven ICC.