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Synergistic anti-myeloma activity of the proteasome inhibitor marizomib and the IMiD immunomodulatory drug pomalidomide.

ABSTRACT: The proteasome inhibitor bortezomib is an effective therapy for the treatment of relapsed and refractory multiple myeloma (RRMM); however, prolonged treatment can be associated with toxicity, peripheral neuropathy and drug resistance. Our earlier studies showed that the novel proteasome inhibitor marizomib is distinct from bortezomib in its chemical structure, mechanisms of action and effects on proteasomal activities, and that it can overcome bortezomib resistance. Pomalidomide, like lenalidomide, has potent immunomodulatory activity and has been approved by the US Food and Drug Administration for the treatment of RRMM. Here, we demonstrate that combining low concentrations of marizomib with pomalidomide induces synergistic anti-MM activity. Marizomib plus pomalidomide-induced apoptosis is associated with: (i) activation of caspase-8, caspase-9, caspase-3 and PARP cleavage, (ii) downregulation of cereblon (CRBN), IRF4, MYC and MCL1, and (iii) suppression of chymotrypsin-like, caspase-like, and trypsin-like proteasome activities. CRBN-siRNA attenuates marizomib plus pomalidomide-induced MM cells death. Furthermore, marizomib plus pomalidomide inhibits the migration of MM cells and tumour-associated angiogenesis, as well as overcomes cytoprotective effects of bone marrow microenvironment. In human MM xenograft model studies, the combination of marizomib and pomalidomide is well tolerated, inhibits tumour growth and prolongs survival. These preclinical studies provide the rationale for on-going clinical trials of combined marizomib and pomalidomide to improve outcome in patients with RRMM.

SUBMITTER: Das DS

PROVIDER: S-EPMC4715649 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Synergistic anti-myeloma activity of the proteasome inhibitor marizomib and the IMiD immunomodulatory drug pomalidomide.

Das Deepika S DS Ray Arghya A Song Yan Y Richardson Paul P Trikha Mohit M Chauhan Dharminder D Anderson Kenneth C KC

British journal of haematology 20151012 5

The proteasome inhibitor bortezomib is an effective therapy for the treatment of relapsed and refractory multiple myeloma (RRMM); however, prolonged treatment can be associated with toxicity, peripheral neuropathy and drug resistance. Our earlier studies showed that the novel proteasome inhibitor marizomib is distinct from bortezomib in its chemical structure, mechanisms of action and effects on proteasomal activities, and that it can overcome bortezomib resistance. Pomalidomide, like lenalidomi ...[more]

PMID: 26456076

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Project description:BackgroundThis retrospective study evaluated the treatment patterns in and overall survival (OS) of multiple myeloma (MM) patients who were refractory to a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD) or who had received three or more prior lines of therapy (LOTs) including a PI and an IMiD.MethodsElectronic health records in the IMS LifeLink and OPTUM databases were screened for indexing periods of 2000-2014 and 2007-2014, respectively. Patients who were refractory to both a PI and an IMiD (criterion 1) or who received three or more prior LOTs (including a PI and an IMiD) and showed disease progression within 60 days of their most recent regimen (criterion 2) comprised the eligible population. Median OS from time of last LOT was assessed for the full cohort, cohorts meeting criteria 1 and 2, and clinically important subgroups.ResultsOf 3,929 and 3,837 patients with MM diagnoses evaluated in the IMS LifeLink and OPTUM databases, 500 and 162 met the eligibility criteria, respectively. Similar median OS was observed for eligible patients in the IMS LifeLink and OPTUM databases (7.9 vs. 7.9 months; p = .5358). In subgroup analyses of the IMS LifeLink data set, median OS was longer in patients <65 years of age than it was for those ?65 years at eligibility (9.5 vs 6.7 months; p < .01) and in patients with good or unreported versus poor performance status at last claim (7.8 or 8.8 vs. 2.9 months; p < .0001).ConclusionThe findings of this survival analysis suggest that outcomes for these patients remain poor despite the availability of newer agents.Implications for practiceThis real-world retrospective study of electronic health records examines the survival outcomes of patients with multiple myeloma who are heavily pretreated or highly refractory to currently approved treatments, including recently approved proteasome inhibitors and immunomodulatory drugs. This survival analysis showed that outcomes for these patients remain poor despite the availability of newer agents, with median overall survival of approximately 8 months. These findings highlight a critical need to develop novel therapies for these patients and also serve as a reference point against which emerging agents for heavily pretreated or highly refractory disease may be evaluated.

Project description:Salinosporamide A (NPI-0052, marizomib) is a naturally occurring proteasome inhibitor derived from the marine actinobacterium Salinispora tropica, and represents a promising clinical agent in the treatment of hematologic malignancies. Recently, these actinobacteria were shown to harbor self-resistance properties to salinosporamide A by expressing redundant catalytically active mutants of the 20S proteasome ?-subunit, reminiscent of PSMB5 mutations identified in cancer cells with acquired resistance to the founding proteasome inhibitor bortezomib (BTZ). Here, we assessed the growth inhibitory potential of salinosporamide A in human acute lymphocytic leukemia CCRF-CEM cells, and its 10-fold (CEM/BTZ7) and 123-fold (CEM/BTZ200) bortezomib-resistant sublines harboring PSMB5 mutations. Parental cells displayed sensitivity to salinosporamide A (IC50 = 5.1 nM), whereas their bortezomib-resistant sublines were 9- and 17-fold cross-resistant to salinosporamide A, respectively. Notably, combination experiments of salinosporamide A and bortezomib showed synergistic activity in CEM/BTZ200 cells. CEM cells gradually exposed to 20 nM salinosporamide A (CEM/S20) displayed stable 5-fold acquired resistance to salinosporamide A and were 3-fold cross-resistant to bortezomib. Consistent with the acquisition of a PSMB5 point mutation (M45V) in CEM/S20 cells, salinosporamide A displayed a markedly impaired capacity to inhibit ?5-associated catalytic activity. Last, compared with parental CEM cells, CEM/S20 cells exhibited up to 2.5-fold upregulation of constitutive proteasome subunits, while retaining unaltered immunoproteasome subunit expression. In conclusion, salinosporamide A displayed potent antileukemic activity against bortezomib-resistant leukemia cells. ?-Subunit point mutations as a common feature of acquired resistance to salinosporamide A and bortezomib in hematologic cells and S. tropica suggest an evolutionarily conserved mechanism of resistance to proteasome inhibitors.

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Synergistic anti-myeloma activity of the proteasome inhibitor marizomib and the IMiD immunomodulatory drug pomalidomide.

Publications

Synergistic anti-myeloma activity of the proteasome inhibitor marizomib and the IMiD immunomodulatory drug pomalidomide.

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