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BACKGROUND: The prognosis for high-risk childhood acute leukaemias remains dismal and established treatment protocols often cause long-term side effects in survivors. This study aims to identify more effective and safer therapeutics for these patients. METHODS: A high-throughput phenotypic screen of a library of 3707 approved drugs and pharmacologically active compounds was performed to identify compounds with selective cytotoxicity against leukaemia cells followed by further preclinical evaluation in patient-derived xenograft models. RESULTS: Auranofin, an FDA-approved agent for the treatment of rheumatoid arthritis, was identified as exerting selective anti-cancer activity against leukaemia cells, including patient-derived xenograft cells from children with high-risk ALL, versus solid tumour and non-cancerous cells. It induced apoptosis in leukaemia cells by increasing reactive oxygen species (ROS) and potentiated the activity of the chemotherapeutic cytarabine against highly aggressive models of infant MLL-rearranged ALL by enhancing DNA damage accumulation. The enhanced sensitivity of leukaemia cells towards auranofin was associated with lower basal levels of the antioxidant glutathione and higher baseline ROS levels compared to solid tumour cells. CONCLUSIONS: Our study highlights auranofin as a well-tolerated drug candidate for high-risk paediatric leukaemias that warrants further preclinical investigation for application in high-risk paediatric and adult acute leukaemias.

Despite remarkable improvements being made in the treatment of childhood acute lymphoblastic leukaemia (ALL), prognosis remains dismal for a certain subgroups of high-risk patients including infants with leukaemia harbouring rearrangement of the Mixed Lineage Leukaemia (MLL) gene, thus warranting development of more effective therapeutics. The approach of drug repurposing, whereby an approved drug may be applied to target a disease other than that for which it was originally intended, is one that is gaining popularity due to the potential to avoid the rising cost and lengthy process of the traditional drug discovery pathway. To identify novel candidates for high-risk leukaemia, a library of approved drugs and pharmacologically active compounds was screened against ALL cell lines with or without MLL gene rearrangement, using a cell-based viability assay. The screen identified two MLL-selective bioactive compounds. The purinergic P2Y receptor agonist and guanylate cyclase inhibitor, 2-chloroadenosine triphosphate, showed in vitro efficacy against MLL-r ALL patient-derived xenografts (PDX) whereby sensitivity was associated with decreased expression of several P2Y receptors including P2RY14, which was additionally found to be differentially expressed in MLL-r vs MLL-wt paediatric ALL patients. The second MLL-selective candidate, SID7969543 which targets Steroidogenic Factor-1 (SF-1), showed activity against a subset of MLL-r and CALM-AF10 leukaemia cell lines and synergized with etoposide and cytarabine in vitro. A subsequent secondary screen aimed at selecting more potent compounds identified two FDA-approved drugs, auranofin and disulfiram, which revealed a common ROS-mediated mechanism in potently inhibiting the viability of high-risk leukaemia cell lines and PDX in vitro. Preclinical testing of drug combinations revealed the potential of combined treatment with auranofin and cytarabine in delaying leukaemia growth in an aggressive MLL-r ALL PDX mouse model. Auranof

Amplification of MYCN is one of the strongest prognostic factors for poor outcome in neuroblastoma, the most common extra-cranial solid tumour in children. With less than 50% of such patients surviving their disease, better therapies are needed. MYC transcription factors up-regulate protein synthesis to drive cancer progression. Since inhibiting protein synthesis is detrimental to the progression of c-MYC driven cancers, targeting this process may offer therapeutic benefit for MYCN-driven neuroblastoma. ABCE1 is a MYC target gene and encodes an ATP-binding cassette protein that powers the dissociation of ribosomes into small and large subunits. This process allows translation re-initiation and continued protein synthesis to provide essential building blocks for cancer growth and metastasis. High tumour ABCE1 expression is correlated with reduced survival of neuroblastoma patients. ABCE1 is thus a putative therapeutic target in MYCN-driven neuroblastoma. Therefore, experiments were conducted to test whether targeting ABCE1-mediated translation can block neuroblastoma progression.ABCE1 suppression by short interfering RNAs impaired the proliferation and migration of MYCN-amplified neuroblastoma cell lines. In contrast, ABCE1 knockdown did not affect these malignant characteristics in neuroblastoma or fibroblast cell lines lacking MYCN amplification. ABCE1 suppression also sensitised neuroblastoma cells to the chemotherapeutics topotecan, mafosfamide and etoposide, further supporting ABCE1 as a potential target in neuroblastoma.Polysome profiling showed that ABCE1 knockdown in MYCN-amplified SK-N-BE(2) neuroblastoma cells reduced translation efficiency. Similar decreases in translation were observed in all other MYCN-amplified cell lines tested, but not in cell lines lacking MYCN amplification. Induction of MYCN expression in the SH-EP Tet21N neuroblastoma cell line substantially increased translation; however, ABCE1 knockdown returned translation to basal levels. Ther

Limited information is available on the identity of antigens targeted by antibodies present in cerebrospinal fluid (CSF) of patients with clinically isolated syndrome (CIS). The aim of this study was to identify novel antigens for CIS and investigate their prognostic potential to predict conversion to multiple sclerosis (MS). We applied serological antigen selection (SAS) to identify antigens interacting with antibodies present in the pooled CSF from four CIS patients, who developed MS. Antibody reactivity towards CIS antigens identified by SAS was tested in CSF and serum from patients with CIS (n = 123/n = 108), MS (n = 65/n = 44), and other (inflammatory) neurological diseases (n = 75/n = 38) as well as in healthy control sera (n = 44). Using SAS, a panel of six novel CIS candidate antigens was identified. CSF antibody reactivity was detected in both CIS and relapsing-remitting (RR) MS. Serum reactivity was significantly increased in CIS and RR-MS as compared with controls (p = 0.03). For two antigens, the frequency of antibody-positive patients was higher in CIS patients who converted to MS as compared with CIS patients without conversion. We identified novel CIS antigens to which antibody reactivity was primarily detected in CIS and RR-MS as compared to controls. Possible prognostic potential could be demonstrated for two antigens.