Cancer Therapy : Preclinical The Novel Organic Arsenical Darinaparsin Induces MAPK-Mediated and SHP 1-Dependent Cell Death in T-cell Lymphoma and Hodgkin Lymphoma Cells and Human Xenograft Models

Purpose: Darinaparsin (Zio-101) is a novel organic arsenical compound with encouraging clinical activity in relapsed/refractory T-cell lymphoma (TCL) and Hodgkin lymphoma (HL); however, little is known about its mechanism of action. Experimental Design: TCL cell lines (Jurkat, Hut78, andHH) andHL cell lines (L428, L540, and L1236) were examined for in vitro cell death by MTT assay and Annexin V–based flow cytometry. Jurkat and L540derived xenografts in SCIDmice were examined for in vivo tumor inhibition and survival. Biologic effects of darinaparsin on the MAPK pathway were investigated using pharmacologic inhibitors, RNAi and transient transfection for overexpression for SHP1 and MEK. Results: Darinaparsin treatment resulted in timeand dose-dependent cytotoxicity and apoptosis in all TCL and HL cell lines. In addition, darinaparsin had more rapid, higher, and sustained intracellular arsenic levels comparedwith arsenic trioxide viamass spectrometry. In vivo experiments with Jurkat (TCL) and L540 (HL)-derived lymphoma xenografts showed significant inhibition of tumor growth and improved survival in darinaparsin-treated SCIDmice. Biologically, darinaparsin caused phosphorylation of ERK (and relevant downstream substrates) primarily by decreasing the inhibitory SHP1 phosphatase and coimmunoprecipitation showed significant ERK/SHP1 interaction. Furthermore, ERK shRNA knockdown or constitutive overexpression of SHP1 resulted in increased apoptosis, whereas cotreatment with pharmacologic MEK inhibitors resulted in synergistic cell death. Conversely, SHP1 blockade (via pharmacologic inhibition or RNAi) and MEK constitutive activation decreased darinaparsin-related cell death. Conclusions:Altogether, these data show that darinaparsin is highly active inHL and TCL and its activity is dependent primarily on MAPK mechanisms. Clin Cancer Res; 20(23); 6023–33. 2014 AACR. Introduction Although many patients with Hodgkin lymphoma (HL) are cured by conventional chemotherapy, there continues to be a subset of patients with refractory disease or relapse. Furthermore, there remains a need to continue to identify targeted, less toxic therapy for the treatment of HL. T-cell lymphomas (TCL) are uncommon and aggressive non-Hodgkin lymphoma that are difficult to treat. Long-term survival rates are <30% to 35% (1). New and targeted therapeutics are desired for the treatment of these lymphomas. Darinaparsin (S-dimethylarsino-glutathione) is a novel organic arsenical compound reported to have encouraging clinical activity, including several complete remission, in patients with relapsed or refractory TCL and HL (2). Darinaparsin was initially discovered as a cytotoxic product derived from arsenic metabolism (3). Subsequent in vitro and in vivo experiments with leukemia showed that darinaparsin was a potent antineoplastic agent (4, 5). In addition, early-phase clinical trials in patients with hematologic malignancies demonstrated that darinaparsin is safer and effective compared with inorganic arsenic trioxide (ATO; refs. 6–8). Moreover, it is known that Molecular Oncology Research Institute and Division of Hematology Oncology, Tufts Medical Center, Department of Medicine, Tufts University School of Medicine, Boston, Massachusetts. Northwestern University Feinberg School of Medicine, Chicago, Illinois. Marlene and Stewart Greenebaum Cancer Center, Department of Medicine, University of Maryland, Baltimore, Maryland. Brigham and Women's Hospital, Boston, Massachusetts. Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois. Robert H. Lurie Cancer Center, Northwestern University, Chicago, Illinois. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Corresponding Author:AndrewM. Evens, Division of Hematology/Oncology, Tufts Cancer Center, Tufts Medical Center, Tufts University School of Medicine, 800 Washington Avenue, Boston, MA 02111. Phone: 617-6368077; Fax: 617-636-7060; E-mail: AEvens@tuftsmedicalcenter.org doi: 10.1158/1078-0432.CCR-14-1532 2014 American Association for Cancer Research. Clinical Cancer Research www.aacrjournals. org 6023 on May 29, 2017. © 2014 American Association for Cancer Research. clincancerres.aacrjournals. org Downloaded from Published OnlineFirst October 14, 2014; DOI: 10.1158/1078-0432.CCR-14-1532