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  • 1
    In: Biomedicines, MDPI AG, Vol. 10, No. 3 ( 2022-03-10), p. 638-
    Abstract: KMT2A-rearranged acute lymphoblastic leukemia (ALL) in infants ( 〈 1 year of age) represents an aggressive type of childhood leukemia characterized by a poor clinical outcome with a survival chance of 〈 50%. Implementing novel therapeutic approaches for these patients is a slow-paced and costly process. Here, we utilized a drug-repurposing strategy to identify potent drugs that could expeditiously be translated into clinical applications. We performed high-throughput screens of various drug libraries, comprising 4191 different (mostly FDA-approved) compounds in primary KMT2A-rearranged infant ALL patient samples (n = 2). The most effective drugs were then tested on non-leukemic whole bone marrow samples (n = 2) to select drugs with a favorable therapeutic index for bone marrow toxicity. The identified agents frequently belonged to several recurrent drug classes, including BCL-2, histone deacetylase, topoisomerase, microtubule, and MDM2/p53 inhibitors, as well as cardiac glycosides and corticosteroids. The in vitro efficacy of these drug classes was successfully validated in additional primary KMT2A-rearranged infant ALL samples (n = 7) and KMT2A-rearranged ALL cell line models (n = 5). Based on literature studies, most of the identified drugs remarkably appeared to lead to activation of p53 signaling. In line with this notion, subsequent experiments showed that forced expression of wild-type p53 in KMT2A-rearranged ALL cells rapidly led to apoptosis induction. We conclude that KMT2A-rearranged infant ALL cells are vulnerable to p53 activation, and that drug-induced p53 activation may represent an essential condition for successful treatment results. Moreover, the present study provides an attractive collection of approved drugs that are highly effective against KMT2A-rearranged infant ALL cells while showing far less toxicity towards non-leukemic bone marrow, urging further (pre)clinical testing.
    Type of Medium: Online Resource
    ISSN: 2227-9059
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
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  • 2
    In: eJHaem, Wiley, Vol. 1, No. 2 ( 2020-11), p. 527-536
    Abstract: MLL ‐rearranged acute lymphoblastic leukemia (ALL) represents a highly aggressive ALL subtype, characterized by aberrant DNA methylation patterns. DNA methyltransferase inhibitors, such as decitabine have previously been demonstrated to be effective in eradicating MLL ‐rearranged ALL cells in vitro. Here, we assessed the in vivo anti‐leukemic potential of low‐dose DNA methyltransferase inhibitor decitabine using a xenograft mouse model of human MLL ‐rearranged ALL. Furthermore, we explored whether prolonged exposure to low‐dose decitabine could chemo‐sensitize MLL ‐rearranged ALL cells toward conventional chemotherapy as well as other known epigenetic‐based and anti‐neoplastic compounds. Our data reveal that decitabine prolonged survival in xenograft mice of MLL ‐rearranged ALL by 8.5 days ( P  = .0181), but eventually was insufficient to prevent leukemia out‐growth, based on the examination of the MLLAF4 cell line SEM. Furthermore, we observe that prolonged pretreatment of low‐dose decitabine mildly sensitized toward the conventional drugs prednisolone, vincristine, daunorubicin, asparaginase, and cytarabine in a panel of MLL ‐rearranged cell lines. Additionally, we assessed synergistic effects of decitabine with other epigenetic‐based or anticancer drugs using high‐throughput drug library screens. Validation of the top hits, including histone deacetylase inhibitor panobinostat, BCL2 inhibitor Venetoclax, MEK inhibitor pimasertib, and receptor tyrosine kinase foretinib, revealed additive and moderate synergistic effects for the combination of each drug together with decitabine in a cell line‐dependent manner.
    Type of Medium: Online Resource
    ISSN: 2688-6146 , 2688-6146
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
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  • 3
    In: Leukemia, Springer Science and Business Media LLC, Vol. 34, No. 11 ( 2020-11), p. 2898-2902
    Type of Medium: Online Resource
    ISSN: 0887-6924 , 1476-5551
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    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
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  • 4
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 78, No. 13_Supplement ( 2018-07-01), p. 1925-1925
    Abstract: BACKGROUND: Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) represent the most common types of cancer among children. Although the survival rates of pediatric ALL and AML have improved substantially over the last decades, the prognosis for some subgroups of pediatric leukemia remain poor. MLL-rearranged infant ALL, MLL-rearranged AML, and NUP98-rearranged AML, for instance, still have 5-year event-free survival rates of only ~40%. Evidently, these high-risk subtypes of childhood leukemia urgently require new treatment strategies in order to improve clinical outcome. AIM: Identification of effective therapeutic drugs for high-risk leukemia subtypes harboring a translocation in the MLL or NUP98 gene, by using a drug repurposing strategy involving high-throughput screening of & gt; 4000 compounds. METHODS: Primary leukemic cells derived from six patients with either MLL-rearranged infant ALL, pediatric MLL-rearranged AML, or pediatric NUP98-rearranged AML at diagnosis, were screened using commercially available drug libraries comprising a total of 4165 compounds. Drug sensitivity was assessed after 4 days treatment with 10 nM, 100 nM and 1000 nM of the library compounds using MTT assays. Potential hits were subsequently validated using cytotoxicity assays with a more extensive range of drug concentrations. RESULTS: The results of our drug screens showed that the most effective drugs, by far, were found for MLL-rearranged infant ALL. For MLL-rearranged AML the number of identified potent drugs was considerably less; notably, all of these compounds identified overlapped with the effective agents also found for MLL-rearranged infant ALL. Remarkably, for NUP98-translocated AML, only a few potential drug hits were identified, suggesting that this type of leukemia might be extremely chemo-resistant. In addition to novel candidate compounds, we also found several agents either recently described to have strong anti-leukemic effects against MLL-rearranged leukemia, such as the BCL2 inhibitors Venetoclax (ABT199) and Navitoclax (ABT263), or the MDM2 inhibitor Idasanutlin (RG7388), as well as finding drugs currently being used in the treatment of MLL-rearranged acute leukemias. Taken together, these observations indicate that high-throughput drug screening on primary patient samples is indeed able to identify effective compounds, validating our experimental approach. Interestingly, while validating newly identified drug hits, we observed a remarkable pattern for compounds effective against MLL-rearranged acute leukemia: the top hits seem to either directly or indirectly associate with p53 activity, albeit from various angles. CONCLUSION: Our data suggests a potential role for p53 in MLL-rearranged acute leukemia, and indicates that targeting p53 may well become an important therapeutic strategy for these types of childhood leukemia. Citation Format: Priscilla Wander, Sandra S. Pinhanços, Bianca Koopmans, M. Emmy M. Dolman, Pauline Schneider, Patricia Garrido Castro, Luke Jones, Susan T.C.J.M. Arentsen-Peters, Mark Kerstjens, Jan Molenaar, Huib N. Caron, Rob Pieters, Michel C. Zwaan, Ronald W. Stam. High-throughput drug library screening identifies potent drugs and novel drug targets for high-risk acute leukemia in children [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1925.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2018
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    detail.hit.zdb_id: 410466-3
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  • 5
    In: Blood, American Society of Hematology, Vol. 138, No. Supplement 1 ( 2021-11-05), p. 2206-2206
    Abstract: MLL-rearranged acute lymphoblastic leukemia (ALL) is characterized by deregulation of the epigenome and shows susceptibility towards epigenetic perturbators such as histone deacetylase (HDAC) inhibitors. Hence, HDACs represent attractive drug targets and a variety of small molecule HDAC inhibitors have been developed and evaluated for the treatment of hematological malignancies. However, most broad-spectrum inhibitors, which simultaneously target the majority of human HDAC isoforms, often induce toxicity, especially in combination with other therapeutic agents. Therefore, selective inhibition of only one or two HDAC isoforms may represent a better alternative, provided that disease-specific dependency on specific HDACs has been identified. We examined the effects of shRNA-mediated knock-down of the class II HDACs (i.e. HDAC4, HDAC5, HDAC6, HDAC7 and HDAC9) in the MLL-rearranged ALL cell lines SEM and ALL-PO. Except for HDAC9, loss of expression (both on the mRNA and protein level) of all HDACs led to strong reductions in viable cells (0.70 to 0.19-fold; p=0.02-0.0016) in both models due to apoptosis, cell cycle arrest, or a combination thereof. Next, we evaluated the in vitro efficacy of a variety of class II HDAC-specific inhibitors on a panel of MLL-rearranged ALL (n=5) using 4-day viability MTT assays. This revealed that the selective HDAC4/5 inhibitor LMK-235 was able to recapitulate the loss-of-function phenotype of HDAC4 and HDAC5. Dose response curves showed complete growth inhibition in MLL-rearranged ALL cell lines (n=5), as well as in primary MLL-rearranged infant ALL patient samples (n=4), with IC 50 values of ~100 nM and 40-100 nM, respectively. Importantly, at these concentrations, LMK-235 hardly affected whole bone marrow samples derived from healthy individuals (n=2), for which IC 50 values were ~1 µM. To further explore the potential of class II HDAC inhibitor-based therapeutic strategies, we performed a combinatorial drug screen to identify compounds that synergize with LMK-235. For this, a compound library (comprising & gt;200 unique agents) was screened in the absence and presence of varying concentrations of LMK235 in the MLL-rearranged cell line models SEM and ALL-PO. This, and subsequent validation experiments in additional cell line models, revealed that Venetoclax (BCL2 inhibitor), Trametinib (MEK/ERK inhibitor), Ponatinib (multi-tyrosine kinase inhibitor) and Omipalisib (a PI3K/mTOR inhibitor) strongly synergized with LMK-235. Average ZIP synergy scores ranged from 10-30, with peak ZIP scores up to 40. Importantly, synergistic effects were consistent over all concentration combinations tested. The addition of 50-100 nM LMK-235 strongly reduced IC 50 values for Omipalisib, Ponatinib and Venetoclax (0.27-fold p=0.003, 0.11-fold p=0.0005, 0.75-fold p=0.0004, respectively) in both models. In preparation to assess the in vivo efficacy of LMK-235 in patient-derived xenograft (PDX) mouse models of MLL-rearranged infant ALL, pharmacokinetic/pharmacodynamic (PK/PD) analysis was performed in immunodeficient NSG mice (n=5). For this, mice were treated with 20 mg/kg of LMK-235, daily administered via intraperitoneal injections for a total of 29 days. While none of the mice showed signs of toxicity or weight loss, LMK-235 plasma levels were stably maintained at concentrations that are highly effective against MLL-rearranged ALL cells in vitro. Taken together, these data demonstrate that various class II HDAC isoforms are targetable vulnerabilities in MLL-rearranged ALL and that pharmaceutical inhibition of HDAC4/5 by LMK-235 represents an attractive therapeutic option. Moreover, high levels of synergy observed between this HDAC inhibitor and various agents belonging to drug classes already reported to be effective against MLL-rearranged ALL, warrants pre-clinical evaluation in vivo. Currently, the assessment of the in vivo efficacy of LMK-235 monotherapy in MLL-rearranged infant ALL PDX models is in progress, after which promising synergistic HDAC inhibitor-based drug combinations will be evaluated. To determine the additional therapeutic value, the efficacy of LMK-235 and promising synergistic combinations will be evaluated in the background of conventional combination chemotherapy, where PDX models will receive a mouse-adapted version of induction therapy currently applied for treatment of MLL-rearranged infant ALL patients. Disclosures No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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