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Maintenance treatment is standard of care for front-line (FL) and platinum-sensitive recurrent ovarian cancer (PSROC) following response to chemotherapy. Adverse events (AEs) on maintenance therapies are common and usually attributable to investigational treatments but could also be unrelated. Randomised controlled trial (RCT) with blinded placebo design is the gold standard for determining the relative differences in efficacy and AEs between treatment arms. We performed a meta-analysis to quantify AE rates in placebo arms of RCTs to determine AEs not due to investigational agents.We performed an electronic search to identify eligible RCTs in FL and PSROC settings. Data from placebo arms were extracted and pooled using the inverse variance method to determine the risk of any AE, overall and specific grade 3 or higher (G ≥ 3) AEs, and AE-related treatment delay, reduction and discontinuation.We identified 13 eligible RCTs (FL, N = 8; PSROC, N = 5) with 2224 patients who received placebo (FL, N = 1541; PSROC, N = 683). The majority experienced an AE of any grade (FL, 93.0%; PSROC, 95.2%). Substantial proportions experienced G ≥ 3 AEs (FL, 14.6%; PSROC, 18.2%). In the FL setting, AEs led to treatment delay in 14.4%, dose reduction in 4.1% and discontinuation in 2.6%. Findings were similar for PSROC: 8.4%, 5.5% and 2.1%, respectively.AEs not due to investigational agents are common in ovarian cancer patients in maintenance therapy RCTs. Potential explanations include the nocebo effect, residual toxicities from previous treatment or underlying disease. Further research is required to identify better approaches to assessing AEs in this population.

DIPG is an aggressive and incurable childhood brain tumour for which new treatments are needed. A high throughput drug screen of 3500 pharmaceutical compounds identified anti-malarials, including quinacrine as having potent activity against DIPG neurospheres. CBL0137, a compound modelled on quinacrine, is a novel anti-cancer compound which targets Facilitates Chromatin Transcription (FACT), a chromatin remodelling complex involved in transcription, replication, and DNA repair. CBL0137 effectively crosses the blood-brain barrier and has recently completed Phase I testing in adult patients. CBL0137 induced apoptosis in DIPG neurospheres and had profound cytotoxic activity against a panel of DIPG cultures. In a DIPG orthotopic model, treatment with CBL0137 significantly improved survival. We found that treatment with CBL0137 up-regulated TP53 and increased histone H3.3 acetylation and tri-methylation in DIPG cells. We therefore examined the interaction between CBL0137 and the histone deacetylase (HDAC) inhibitor panobinostat. In vitro experiments showed that the two agents had profound synergistic activity against DIPG neurospheres in clonogenic assays and enhanced caspase activation and apoptosis. The FACT subunit SSRP1 was found to directly interact with H3.3K27M and treatment with CBL0137 targeted this epigenetic defect, restoring histone H3.3 trimethylation and leading to tumor cell death. Transcriptomic analysis and immunoblotting indicated that combination treatment activated signalling pathways controlled by Retinoblastoma (RB)/E2F1 and subsequently increased phosphorylation and enzymatic activity of enhancer of zeste homolog 2 (EZH2). Consistent with the in vitro results, the combination of CBL0137 and panobinostat significantly prolonged survival in two independent orthotopic models of DIPG, while histological analysis showed restoration of H3K27me3 and decreased Ki67 positive cells. In addition to panobinostat, CBL0137 has been found to combine synergistically in vitro and in vivo with PARP and BET inhibitors. Given these promising results, a paediatric trial of CBL0137 will open through the Children’s Oncology Group with an expansion cohort for DIPG patients.

Diffuse intrinsic pontine glioma (DIPG) is an aggressive and incurable childhood brain tumor for which new treatments are needed. A high throughput drug screen of 3600 pharmaceutical compounds found that anti-malarials, including quinacrine had potent activity against DIPG neurospheres. CBL0137 is a novel anti-cancer compound developed from quinacrine, which targets Facilitates Chromatin Transcription (FACT), a chromatin remodelling complex involved in transcription, replication, and DNA repair. We have found that CBL0137 displays profound cytotoxic activity against a panel of patient derived DIPG cultures, inhibiting cell proliferation and clonogenic potential, restoring tumor suppressor TP53 and Rb activity and inducing cell death through induction of apoptosis. Moreover, in an orthotopic model of DIPG, treatment with CBL0137 significantly extended animal survival. Histone mutations leading to the loss of histone trimethylation result in epigenetic dysregulation driving DIPG tumorigenesis. Treatment with CBL0137 targets this epigenetic defect, restoring both histone H3.3 acetylation and trimethylation and leading to tumor cell death. Combined epigenetic treatment with the histone deacetylase (HDAC) inhibitor panobinostat led to inhibition of the Rb/E2F1 pathway, and increased the enzymatic activity of enhancer of zeste homolog 2 (EZH2), leading to the restoration of H3K27 trimethylation. This combination therapy had synergistic activity against DIPG neurospheres with induction of apoptosis. Consistent with the in vitro results, the combination of CBL0137 and panobinostat significantly prolonged the survival of mice bearing DIPG orthografts suggesting a potential treatment strategy for DIPG.

Diffuse intrinsic pontine glioma (DIPG) is an aggressive and incurable childhood brain tumour for which new treatments are needed. A high throughput drug screen of 3500 pharmaceutical compounds identified anti-malarials, including quinacrine as having potent activity against DIPG neurospheres. CBL0137, a compound modelled on quinacrine, is an anti-cancer compound which targets Facilitates Chromatin Transcription (FACT), a chromatin remodelling complex involved in transcription, replication, and DNA repair. CBL0137 effectively crosses the blood-brain barrier and is currently in Phase I trials in adult cancer. CBL0137 induced apoptosis in DIPG neurospheres in vitro and had profound cytotoxic activity against a panel of DIPG cultures. In a DIPG orthotopic model, treatment with CBL0137 significantly improved survival. We found that treatment with CBL0137 up-regulated TP53 and increased histone H3.3 acetylation and tri-methylation in DIPG cells. We therefore examined the interaction between CBL0137 and the HDAC inhibitor, panobinostat. In vitro experiments showed that the two agents had profound synergistic activity against DIPG neurospheres in clonogenic assays and enhanced apoptosis. Transcriptomic analysis and immunoblotting indicated that combination treatment activated signalling pathways controlled by Retinoblastoma (RB)/E2F1 and subsequently increased phosphorylation and enzymatic activity of enhancer of zeste homolog 2 (EZH2). Consistent with the in vitro results, the combination of CBL0137 and panobinostat significantly prolonged the survival of two orthotopic models of DIPG, while histological analysis showed increased H3K27me3 and decreased Ki67 positive cells. Given these promising results, a paediatric trial of CBL0137 is planned to open through the Children’s Oncology Group with an expansion cohort for DIPG patients.

Background: Despite the success of chemotherapy in improving the overall survival rate of childhood cancer, a number of types of children's cancers still have dismal outcomes. Included here are high risk neuroblastomas, Diffuse Intrinsic Pontine Gliomas (DIPG), and infant leukemias with MLL translocations. New treatments for these aggressive childhood cancers are urgently needed. Evidence is emerging of the importance of alterations in chromatin modifier genes in pediatric cancers. In this regard, CBL0137 is a carbazole-based anti-cancer agent with a unique mechanism of action. It is an indirect inhibitor of the chromatin remodeling complex FACT (Facilitates Chromatin Transcription). Inhibition of FACT by CBL0137 modulates the activity of several transcription factors involved in cancer: NF-kB and HSF1 are suppressed, while p53 is activated (Science Transl Med, 2011). We have examined FACT expression in neuroblastoma, DIPG and MLL leukemia, as well as the efficacy of CBL0137 in preclinical models of these diseases. Methods: Expression of the FACT subunits, SSRP1 and SPT16, was examined in neuroblastoma, DIPG and MLL leukemia cells using RT-PCR and Western analysis. The clinical significance of SSRP1 and SPT16 was also analysed using expression array data on 650 primary untreated neuroblastomas. Colony-forming assays were used to study the effect of CBL0137, either alone or combined with chemotherapeutic drugs. Cohorts of neuroblastoma, DIPG and MLL leukemia xenografted mice, as well as neuroblastoma-prone TH-MYCN mice, were treated with CBL0137, alone or combined with chemotherapeutic drugs. Results: High levels of SSRP1 and SPT16 expression were observed in all three types of child cancer. In addition, in neuroblastoma, the two FACT subunits were associated with MYCN amplification, and were strongly predictive of poor outcome (p Conclusions: Targeting FACT offers a highly promising novel therapeutic approach for aggressive childhood cancers. The results for CBL0137 are as good or better than any chemotherapy regimens we have tested in our preclinical models, and a Phase I COG trial of this nongenotoxic agent in refractory pediatric cancer patients is currently being planned. Citation Format: Michelle Haber, Jayne Murray, Laura Gamble, Ashleigh Carnegie-Clark, Hannah Webber, Michelle Ruhle, Michelle J. Henderson, Shiloh Middlemass, Daniel Carter, Maria Tsoli, Anahid Ehteda, Sandy Simon, Andre Oberthuer, Matthias Fischer, Katerina Gurova, Catherine Burkhart, Andrei Purmal, Richard B. Lock, David Ziegler, Glenn M. Marshall, Andrei V. Gudkov, Murray D. Norris. The FACT histone chaperone complex is highly expressed in aggressive drug refractory childhood cancers and the anti-FACT compound CBL0137 represents a highly promising therapeutic approach in this setting. [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 1611. doi:10.1158/1538-7445.AM2015-1611