Inhibition of eIF2α Dephosphorylation Maximizes Bortezomib Efficiency and Eliminates Quiescent Multiple Myeloma Cells Surviving Proteasome Inhibitor Therapy

Abstract Recent studies underscore that multiple myeloma is an immunogenic disease and suggest that it can be effectively treated by T cell based immunotherapy via immunomodulation. This strategy might be synergistically complemented by therapeutic vaccination, which may help induce and guide specific anti-cancer T cell responses. We have recently conducted a study which directly characterized the antigenic landscape of myeloma by mass spectrometric analysis of naturally presented HLA ligands and identified a panel of T cell epitopes characterized by exquisite myeloma-association (Walz, Stickel et. al., Blood 2015). As standard of care in myeloma includes proteasome inhibitor therapy and the proteasome plays a central role in the generation of MHC-presented peptides, it is of great importance to thoroughly characterize and take into account the effects of this treatment on the antigenic landscape of myeloma cells and implement only robustly presented targets for peptide vaccine design. This is even more important Here we present a mass spectrometry-based study, which longitudinally and semi-quantitatively maps the effects of treatment with the 2nd generation proteasome inhibitor carfilzomib in an in vitro model of multiple myeloma. We observed considerable plasticity of the HLA class I ligandome of MM.1S cells after treatment with carfilzomib with 17.9±1.1.% (mean of 3 biological replicates ± SD) of HLA ligands showing significant modulation (fold change ≥ 4, P ≤ 0.01) at t24h compared to mock-treated controls (down-modulated: 11.5±1.1%, up-modulated: 6.3±0.6%). We were able to longitudinally tracke the abundance of 28 previously defined myeloma antigens, confirming robust (16/28, 57.1%) or even increased presentation (8/28, 28.6%) under treatment for the majority of these peptides. However, - importantly - we observed highly distortive effects of carfilzomib treatment on the HLA allotype distribution of target cells, which manifested as a marked reduction of HLA ligands restricted by HLA-A*23:01 and A*24:02 (-62.5±1.8% and -57.0±0.6%, respectively, at t=24h after treatment). These findings indicate strong allotype-specific effects of carfilzomib on the antigenic landscape of myeloma cells, which we interpret to be a direct reflection of the mechanism of action of this drug. As a significant proportion of the U.S. population are carriers of the affected alleles (A*23:01: 8.2%; A*24:02: 22.6%), these findings could have broad implications for the design or implementation of antigen-specific therapies in patients under proteasome inhibitor treatment. Furthermore, these findings might indicate the possibility of altered cancer immunosurveillance as a consequence of proteasome inhibitor therapy. Disclosures Weisel: Amgen: Consultancy, Honoraria, Other: Travel Support; Onyx: Consultancy, Honoraria; Novartis: Other: Travel Support; Janssen Pharmaceuticals: Consultancy, Honoraria, Other: Travel Support, Research Funding; Noxxon: Consultancy; Celgene: Consultancy, Honoraria, Other: Travel Support, Research Funding; BMS: Consultancy, Honoraria, Other: Travel Support.

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Synergistic activity of the proteasome inhibitor PS-341 with non-myeloablative 153-Sm-EDTMP skeletally targeted radiotherapy in an orthotopic model of multiple myeloma

Blood ◽

10.1182/blood-2005-09-3870 ◽

2006 ◽

Vol 107 (10) ◽

pp. 4063-4070 ◽

Cited By ~ 25

Author(s):

Apollina Goel ◽

Angela Dispenzieri ◽

Susan M. Geyer ◽

Suzanne Greiner ◽

Kah-Whye Peng ◽

...

Keyword(s):

Multiple Myeloma ◽

Proteasome Inhibitor ◽

In Vivo Model ◽

Synergistic Activity ◽

Mineral Density ◽

Orthotopic Model ◽

Targeted Radiotherapy ◽

Myeloma Cells ◽

Cell Counts

Multiple myeloma is a highly radiosensitive skeletal malignancy, but bone-seeking radionuclides have not yet found their place in disease management. We previously reported that the proteasome inhibitor PS-341 selectively sensitizes myeloma cells to the lethal effects of ionizing radiation. To extend these observations to an in vivo model, we combined PS-341 with the bone-seeking radionuclide 153-Sm-EDTMP. In vitro clonogenic assays demonstrated synergistic killing of myeloma cells exposed to both PS-341 and 153-Sm-EDTMP. Using the orthotopic, syngeneic 5TGM1 myeloma model, the median survivals of mice treated with saline, 2 doses of PS-341 (0.5 mg/kg), or a single nonmyeloablative dose of 153-Sm-EDTMP (22.5 MBq) were 21, 22, and 28 days, respectively. In contrast, mice treated with combination therapy comprising 2 doses of PS-341 (0.5 mg/kg), 1 day prior to and 1 day following 153-Sm-EDTMP (22.5 MBq) showed a significantly prolonged median survival of 49 days (P < .001). In addition to prolonged survival, this treatment combination yielded reduced clonogenicity of bone marrow–resident 5TGM1 cells, reduced serum myeloma–associated paraprotein levels, and better preservation of bone mineral density. Myelosuppression, determined by peripheral blood cell counts and clonogenicity assays of hematopoietic progenitors, did not differ between animals treated with 153-Sm-EDTMP alone versus those treated with the combination of PS-341 plus 153-Sm-EDTMP. PS-341 is a potent, selective in vivo radiosensitizer that may substantially affect the efficacy of skeletal-targeted radiotherapy in multiple myeloma.

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Spliced XBP1 Levels Determine Sensitivity of Multiple Myeloma Cells to Proteasome Inhibitor Bortezomib Independent of the Unfolded Protein Response Mediator GRP78

Frontiers in Oncology ◽

10.3389/fonc.2019.01530 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 2

Author(s):

Bojana Borjan ◽

Johann Kern ◽

Normann Steiner ◽

Eberhard Gunsilius ◽

Dominik Wolf ◽

...

Keyword(s):

Multiple Myeloma ◽

Unfolded Protein Response ◽

Proteasome Inhibitor ◽

Myeloma Cells ◽

Unfolded Protein ◽

The Unfolded Protein Response ◽

Protein Response

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Synergistic Induction of Oxidative Injury and Apoptosis in Human Multiple Myeloma Cells by the Proteasome Inhibitor Bortezomib and Histone Deacetylase Inhibitors

Clinical Cancer Research ◽

10.1158/1078-0432.ccr-03-0561 ◽

2004 ◽

Vol 10 (11) ◽

pp. 3839-3852 ◽

Cited By ~ 281

Author(s):

Xin-Yan Pei ◽

Yun Dai ◽

Steven Grant

Keyword(s):

Multiple Myeloma ◽

Histone Deacetylase ◽

Proteasome Inhibitor ◽

Histone Deacetylase Inhibitors ◽

Oxidative Injury ◽

Myeloma Cells ◽

Human Multiple Myeloma ◽

Synergistic Induction

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In Vitro and In Vivo Selective Antitumor Activity of a Novel Orally Bioavailable Proteasome Inhibitor MLN9708 against Multiple Myeloma Cells

Clinical Cancer Research ◽

10.1158/1078-0432.ccr-11-0476 ◽

2011 ◽

Vol 17 (16) ◽

pp. 5311-5321 ◽

Cited By ~ 206

Author(s):

Dharminder Chauhan ◽

Ze Tian ◽

Bin Zhou ◽

Deborah Kuhn ◽

Robert Orlowski ◽

...

Keyword(s):

Multiple Myeloma ◽

Antitumor Activity ◽

Proteasome Inhibitor ◽

Myeloma Cells ◽

Orally Bioavailable

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The Proteasome Inhibitor Bortezomib Stimulates Osteoblastic Differentiation of Human Osteoblast Precursor Cells Via Upregulation of Vitamin D Receptor Signaling

Blood ◽

10.1182/blood.v116.21.1899.1899 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1899-1899

Author(s):

Martin Kaiser ◽

Maren Mieth ◽

Orhan Sezer ◽

Ulrike Heider

Keyword(s):

Multiple Myeloma ◽

Vitamin D ◽

Proteasome Inhibitor ◽

Research Funding ◽

Fold Increase ◽

Osteoblastic Differentiation ◽

Luciferase Reporter ◽

Human Osteoblast ◽

Myeloma Cells ◽

Osteoblast Precursors

Abstract Abstract 1899 Introduction In multiple myeloma (MM), interactions of the malignant plasma cell clone with the bone marrow microenvironment lead to an enhanced osteoclast recruitment and impaired osteoblast activity. The proteasome inhibitor bortezomib has been shown to suppress osteoclast activity, and there is recent evidence that bortezomib enhances osteoblast differentiation. The aim of this study was to investigate the effects of bortezomib on human osteoblast precursors, focusing on vitamin D (VD) dependent osteoblastic differentiation. Since vitamin D receptor (VDR) is degraded by the proteasome, we hypothesized that bortezomib could influence its signaling and hence vitamin D induced osteoblastic differentiation. This might be of clinical importance, since an increased rate of vitamin D deficiency has recently been reported in patients with MM. Methods Primary human mesenchymal stem cells (hMSC) and primary human osteoblasts (hOB) were isolated from bone marrow aspirates or from bone fragments of healthy donors undergoing orthopedic surgery, respectively. Ascorbic acid and β-glycerolphosphate were used for osteoblastic stimulation (OS), either in combination with or without vitamin D. In order to analyze the effects of proteasome inhibition on osteoblastic differentiation and activity, hMSC and hOB were incubated with bortezomib at subapoptotic doses (1 - 5 nM). In addition, coculture experiments of hMSC, hOB and myeloma cells were performed. Expression of osteocalcin and osteopontin (OPN) were quantified by real-time PCR as markers of osteoblastic lineage differentiation. Expression of VDR was analyzed by western blot in subcellular fractions and VDR signaling was investigated using luciferase reporter assays. Results In coculture experiments, myeloma cells inhibited the vitamin D dependent differentiation and activity of osteoblast precursors, e.g. coculture of hMSC with the myeloma cell line LP-1 for 4 days decreased their osteocalcin expression by 58%. Treatment with bortezomib led to an increased osteoblastic differentiation of hMSC and hOB by OS, represented by an enhanced expression of osteoblast markers osteocalcin and OPN. Importantly, this effect could be further increased, when vitamin D was added. In hMSC stimulated with OS only, addition of 5 nM bortezomib led to an 18.3 fold increase in OPN mRNA expression. In comparison, hMSC stimulated with OS + vitamin D showed a 27.5 fold increase in OPN mRNA with the addition of bortezomib. Osteocalcin expression was increased 1.9 fold by bortezomib in the presence of OS and vitamin D, but not with OS alone. Similar results were obtained with osteoblasts: Incubation with bortezomib slightly increased osteocalcin and OPN mRNA expression in cells stimulated with OS only (1.3 fold and 2.4 fold, respectively). In comparison, in cells stimulated with OS and vitamin D, bortezomib elevated osteocalcin and OPN expression 2.9 fold and 5.5 fold, respectively. Bortezomib led to an increase in nuclear VDR levels in hMSC in western blot analyses. Primary hMSC transfected with a VDR luciferase reporter construct showed a 3.7 fold increase in VDR signaling with bortezomib. Conclusion Our data show that bortezomib stimulates osteoblastic differentiation of hMSCs and hOBs and acts, at least in part, through VDR signaling. Substitution of vitamin D in multiple myeloma patients treated with bortezomib may be beneficial for bone turnover and needs clinical evaluation. Disclosures: Kaiser: Johnson & Johnson: Research Funding. Mieth:Johnson & Johnson: Research Funding. Sezer:Johnson & Johnson: Research Funding. Heider:Johnson & Johnson: Research Funding.

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