Summary Aneuploidy is common in paediatric B‐cell precursor acute lymphoblastic leukaemia (ALL). Specific subgroups, such as high hyperdiploidy (>50 chromosomes or DNA Index ≥1·16) and hypodiploidy (<45 chromosomes), predict outcome of patients after primary treatment. Whether aneuploidy has a prognostic value for relapsed disease is yet to be determined. Using DNA index and centromere screening by multiplex ligation‐dependent probe amplification, we investigated aneuploidy in 413 children treated for first relapse of B‐cell precursor ALL according to the ALL‐REZ BFM 2002 protocol. Ten‐year event‐free survival of patients with high hyperdiploid relapses approached 70%, whereas it was only 40% in low hyperdiploid relapses. Three patients with apparent hyperdiploid relapse had TP53 mutations. In these cases, array‐based allelotyping revealed a hypodiploid origin with absence of the hypodiploid founder clone (masked hypodiploidy). Collectively, patients with evident or masked hypodiploid relapses showed an extremely low event‐free survival rate of 9%. Importantly, the current relapse risk stratification did not identify cases with masked hypodiploidy as high‐risk patients, due to their favourable clinical presentation. In multivariate analysis, hypodiploidy proved to be an independent prognostic factor. This finding supports stratification of relapses with hypodiploid origin into high‐risk arms in future trials or allocation of patients to alternative treatment approaches.

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Abstract. Acute lymphoblastic leukemia (ALL) accounts for 30% of all pediatric cancers. Currently available treatments exhibit toxicity and certain patients may develop resistance. Thus, less toxic and chemoresistance-reversal agents are required. In the present study, the potential effect of curcumin, a component of Curcuma longa, as a pharmacological co-adjuvant of several chemotherapeutic agents against ALL, including prednisone, 6-mercaptopurine, dexamethasone, cyclophosphamide, l-asparaginase, vincristine, daunorubicin, doxorubicin, methotrexate and cytarabine, was investigated in the REH ALL cell line cultures treated in combination with chemotherapeutic agents and curcumin. The results of cell viability, gene expression and activation of NF-κB and caspase 3 indicated that curcumin potentiates the anticancer effects of the aforementioned chemotherapeutic agents in the REH ALL cell line. Following treatment with the above chemotherapeutic agents, curcumin enhanced caspase-3 activation and downregulated nuclear factor-kappa B (NF-κB) activation. Curcumin also downregulated the oxidative stress induced by certain chemotherapies. Notably, curcumin did not affect the gene expression of cell survival proteins such as B-cell lymphoma (Bcl)-2, Bcl-extra large, survivin, c-Myc and cyclin D1, which are regulated by the NF-κB transcription factor. In conclusion, curcumin has the potential to improve the effect of chemotherapeutic agents against ALL.

Only half of patients with relapsed B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) currently survive with standard treatment protocols. Predicting individual patient responses to defined drugs prior to application would help therapy stratification and could improve survival. With the purpose to aid personalized targeted treatment approaches, we developed a human–zebrafish xenograft (ALL-ZeFiX) assay to predict drug response in a patient in 5 days. Leukemia blast cells were pericardially engrafted into transiently immunosuppressed Danio rerio embryos, and engrafted embryos treated for the test case, venetoclax, before single-cell dissolution for quantitative whole blast cell analysis. Bone marrow blasts from patients with newly diagnosed or relapsed BCP-ALL were successfully expanded in 60% of transplants in immunosuppressed zebrafish embryos. The response of BCP-ALL cell lines to venetoclax in ALL-ZeFiX assays mirrored responses in 2D cultures. Venetoclax produced varied responses in patient-derived BCP-ALL grafts, including two results mirroring treatment responses in two refractory BCP-ALL patients treated with venetoclax. Here we demonstrate proof-of-concept for our 5-day ALL-ZeFiX assay with primary patient blasts and the test case, venetoclax, which after expanded testing for further targeted drugs could support personalized treatment decisions within the clinical time window for decision-making.