ABSTRACT
Recent preclinical evidence has suggested that Ewing Sarcoma (ES) bearing EWSR1-ETS fusions could be particularly sensitive to PARP inhibitors (PARPinh) in combination with DNA damage repair (DDR) agents. Trabectedin is an antitumoral agent that modulates EWSR1-FLI1 transcriptional functions, causing DNA damage. Interestingly, PARP1 is also a transcriptional regulator of EWSR1-FLI1, and PARPinh disrupts the DDR machinery. Thus, given the impact and apparent specificity of both agents with regard to the DNA damage/DDR system and EWSR1-FLI1 activity in ES, we decided to explore the activity of combining PARPinh and Trabectedin in in vitro and in vivo experiments. The combination of Olaparib and Trabectedin was found to be highly synergistic, inhibiting cell proliferation, inducing apoptosis, and the accumulation of G2/M. The drug combination also enhanced γH2AX intranuclear accumulation as a result of DNA damage induction, DNA fragmentation and global DDR deregulation, while EWSR1-FLI1 target expression remained unaffected. The effect of the drug combination was corroborated in a mouse xenograft model of ES and, more importantly, in two ES patient-derived xenograft (PDX) models in which the tumors showed complete regression. In conclusion, the combination of the two agents leads to a biologically significant deregulation of the DDR machinery that elicits relevant antitumor activity in preclinical models and might represent a promising therapeutic tool that should be further explored for translation to the clinical setting.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Dioxoles/pharmacology , Phthalazines/pharmacology , Piperazines/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Sarcoma, Ewing/drug therapy , Tetrahydroisoquinolines/pharmacology , Animals , Cell Line, Tumor , Child , DNA Damage , Dioxoles/administration & dosage , Drug Synergism , Humans , Male , Mice , Mice, Inbred NOD , Mice, SCID , Phthalazines/administration & dosage , Piperazines/administration & dosage , Poly(ADP-ribose) Polymerase Inhibitors/administration & dosage , Random Allocation , Sarcoma, Ewing/genetics , Sarcoma, Ewing/pathology , Tetrahydroisoquinolines/administration & dosage , Trabectedin , Xenograft Model Antitumor AssaysABSTRACT
Carcinoma in situ (CIS) is a non-papillary high-grade, potentially aggressive, and unpredictable manifestation of bladder urothelial carcinoma. The aim of this study was to assess patterns of Cyclin D3 gene amplification in Bacillus Calmette-Guerin (BCG)-treated CIS and correlate gene status with recurrence-free and progression-free survival. A sequential cohort series of 28 primary (isolated) or secondary (concomitant) bladder CIS samples in which there was enough tissue material to assess Cyclin D3 gene status by fluorescent in situ hybridization was the study group. Cyclin D3 gene amplification was present in 29% of secondary CIS; none of primary CIS samples had Cyclin D3 gene amplification. Cyclin D3 amplification was related to recurrence- (p = 0.046) and progression-free survival (p = 0.002). Type of bladder CIS (primary vs. secondary) was unrelated to recurrence- or progression-free survival in the current series. Cox's regression analysis selected Cyclin D3 as an independent predictor of progression-free survival (p = 0.041, relative risk = 61.503, 95% confidence interval = 1.1-274.710). None of primary CIS cases recurred on follow-up; nine secondary CIS recurred and four of them progressed to invasive bladder carcinoma HG T1 (n = 1), T2b N0M0 (n = 1), T3b N1M0 (n = 1) and T4aN1M1 (n = 1). Mean recurrence ± SD (months) occurred at 19.5 ± 2.06 (95% (confidence interval (CI)), 15.5-23.6); mean progression (months) occurred at 23.8 ± 1.46 (95% (CI), 20.9-26.7). Our study suggests that Cyclin D3 gene amplification might be a predictor of aggressiveness in BCG-treated CIS.
