Pathways to which the identified 24 genes downregulated by JQ1 treatment in CCA2 (Figure 5) contribute.

Time course of increase in tumor volume in mice treated with vehicle (VC) or JQ1.

Immunoblot analysis showing that JQ1 downregulates TEK, Chk1, MSH2 and LCK expression in CCA2 tumors, but not in CCA1 tumors.

Immunohistochemistry analysis and nuclear expression indices of BRD4 in first generation (F1) CCA3, CCA4 and CCA5.

Patient-derived xenograft (PDX) models of cholangiocarcinoma (CCA): tumor growth and histology.

EGFR and c-Myc proteins are overexpressed to similar levels in F0 and corresponding F1 tumors.

Gene products downregulated greater than or equal to 2.4-fold by JQ1 in CCA1 tumors.

Abstract Cholangiocarcinoma (CCA) is a fatal disease with a 5-year survival of <30%. For a majority of patients, chemotherapy is the only therapeutic option, and virtually all patients relapse. Gemcitabine is the first-line agent for treatment of CCA. Patients treated with gemcitabine monotherapy survive ∼8 months. Combining this agent with cisplatin increases survival by ∼3 months, but neither regimen produces durable remissions. The molecular etiology of this disease is poorly understood. To facilitate molecular characterization and development of effective therapies for CCA, we established a panel of patient-derived xenograft (PDX) models of CCA. We used two of these models to investigate the antitumor efficacy and mechanism of action of the bromodomain inhibitor JQ1, an agent that has not been evaluated for the treatment of CCA. The data show that JQ1 suppressed the growth of the CCA PDX model CCA2 and demonstrate that growth suppression was concomitant with inhibition of c-Myc protein expression. A second model (CCA1) was JQ1-insensitive, with tumor progression and c-Myc expression unaffected by exposure to this agent. Also selective to CCA2 tumors, JQ1 induced DNA damage and apoptosis and downregulated multiple c-Myc transcriptional targets that regulate cell-cycle progression and DNA repair. These findings suggest that c-Myc inhibition and several of its transcriptional targets may contribute to the mechanism of action of JQ1 in this tumor type. We conclude that BET inhibitors such as JQ1 warrant further investigation for the treatment of CCA. Mol Cancer Ther; 17(1); 107–18. ©2017 AACR.

Abstract Cholangiocarcinoma (CCA) is a lethal malignancy of the biliary epithelium that can arise in any part of the biliary tree. Surgery is the only curative treatment for CCA, but only ∼30% of patients present with resectable disease. The remaining 70% of patients present with advanced or metastatic disease and, if eligible, undergo systemic chemotherapy with the first-line combination of gemcitabine and cisplatin. This combination was shown in a phase II clinical trial to significantly increase median survival from 8.1 to 11.7 months, compared to gemcitabine alone. In order to improve on current treatment, pre-clinical evaluation of novel therapeutics is essential to improving outcome. Unfortunately, the paucity of data describing characteristics common to CCA make development of targeted therapy difficult. However, as is true for other types of solid tumors, c-Myc expression likely contributes to CCA phenotype: c-Myc expression has been observed in 95% of CCA tumors, and experimental down-regulation of c-Myc decreases the invasive potential of CCA cells in vitro. Recently it has become possible to inhibit expression of c-Myc using BET inhibitors. Therefore, we evaluated the efficacy of the bromodomain (BET) inhibitor JQ1 using in vivo models of CCA. The five patient-derived xenograft (PDX) models of CCA that we developed are the first such models to be reported. These models retain the heterogeneity, architecture and specific genetic characteristics of the primary tumors from which they were derived. We used three of these models to examine whether the BET inhibitor JQ1 inhibited CCA tumor growth and generated expression profiles of vehicle- and drug-treated tumors. We administered 50 mg/kg of JQ1 i.p. daily for 20 days and monitored tumor growth. This treatment regimen was well tolerated by tumor-bearing mice, without apparent toxicity. Our data demonstrate that JQ1 suppressed tumor growth in two of the three models, compared to vehicle control treated mice. The data also showed that JQ1-treated tumors had lower levels of c-Myc RNA (↓5-fold) and protein and of RNA encoding multiple transcriptional targets downstream of this oncogenic transcription factor. We conclude that BET inhibitors such as JQ1 warrant further investigation as potentially effective drugs for the treatment of CCA. Citation Format: Patrick L. Garcia, Aubrey L. Miller, Kelly Kreitzburg, Tracy L. Gamblin, Leona N. Council, John D. Christein, Pablo Arnoletti, Marty Heslin, Sushanth Reddy, Joseph H. Richardson, Eddy S. Yang, Jun Qi, James E. Bradner, Karina J. Yoon. Bromodomain inhibitor JQ1 inhibits cholangiocarcinoma tumor growth in patient-derived xenograft models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1779. doi:10.1158/1538-7445.AM2015-1779

Pancreatic cancer is the one of the deadliest of all malignancies. The five year survival rate for patients with this disease is 3-5%. Thus, there is a compelling need for novel therapeutic strategies to improve the clinical outcome for patients with pancreatic cancer. Several groups have demonstrated for other types of solid tumors that early passage human tumor xenograft models can be used to define some genetic and molecular characteristics of specific human tumors. Published studies also suggest that murine tumorgraft models (early passage xenografts derived from direct implantation of primary tumor specimens) may be useful in identifying compounds with efficacy against specific tumor types. Because pancreatic cancer is a fatal disease and few well-characterized model systems are available for translational research, we developed and characterized a panel of pancreatic tumorgraft models for biological evaluation and therapeutic drug testing. Of the 41 primary tumor specimens implanted subcutaneously into mice, 35 produced viable tumorgraft models. We document the fidelity of histological and morphological characteristics and of KRAS mutation status among primary (F0), F1, and F2 tumors for the twenty models that have progressed to the F3 generation. Importantly, our procedures produced a take rate of 85%, higher than any reported in the literature. Primary tumor specimens that failed to produce tumorgrafts were those that either contained <10% tumor cells or that were obtained from significantly smaller primary tumors. In view of the fidelity of characteristics of primary tumor specimens through at least the F2 generation in mice, we propose that these tumorgraft models represent a useful tool for identifying critical characteristics of pancreatic tumors and for evaluating potential therapies.

Liles, Joe Spencer MD; Frolov, Andrey MD, PhD; Tzeng, Ching-Wei D. MD; Frost, Andra R. MD; Kulesza, Piotr MD, PhD; Christein, John D. MD; Heslin, Marty J. MD; Arnoletti, Juan Pablo MD Author Information