Papers by Johan van Meerloo
Blood Advances, Mar 4, 2022
Vaccination guidelines for patients treated for hematological diseases are typically conservative... more Vaccination guidelines for patients treated for hematological diseases are typically conservative. Given their high risk for severe coronavirus infectious disease 2019 (COVID-19) it is important to identify those patients that benefit from vaccination. We prospectively quantified serum IgG antibodies to spike subunit 1 (S1) antigens during and after 2-dose mRNA-1273 (Spikevax/Moderna) vaccination in hematology patients. Obtaining S1 IgG {greater than or equal to}300 binding antibody units (BAU)/ml was considered adequate as it represents the lower level of S1 IgG concentration obtained in healthy individuals and it correlates with potent virus neutralization. Selected patients (n=723) were severely immunocompromised due to their disease or treatment thereof. Nevertheless, more than 50% of patients obtained S1 IgG {greater than or equal to}300 BAU/ml after 2-dose mRNA-1273. All patients with sickle cell disease or chronic myeloid leukemia obtained adequate antibody concentrations. Around 70% of patients with chronic graft versus host disease (GvHD), multiple myeloma, or untreated chronic lymphocytic leukemia (CLL) obtained S1 IgG {greater than or equal to}300 BAU/ml. Ruxolitinib or hypomethylating therapy but not high-dose chemotherapy blunted responses in myeloid malignancies. Responses in lymphoma patients, CLL patients on ibrutinib, and chimeric antigen receptor T cell recipients were low. The minimal time-interval after autologous hematopoietic cell transplantation (HCT) to reach adequate concentrations was <2 months for multiple myeloma, 8 months for lymphoma, and 4-6 months after allogeneic HCT. Serum IgG4, absolute B and NK cell number and number of immunosuppressants predicted S1 IgG {greater than or equal to}300 BAU/ml. Hematology patients on chemotherapy, shortly after HCT, or with chronic GvHD should not be precluded from vaccination. Netherlands Trial Register NL9553.
Purpose: Daratumumab treatment results in a marked reduction of CD38 expression on multiple myelo... more Purpose: Daratumumab treatment results in a marked reduction of CD38 expression on multiple myeloma cells. The aim of this study was to investigate the clinical implications and the underlying mechanisms of daratumumab-mediated CD38 reduction.Experimental Design: We evaluated the effect of daratumumab alone or in combination with lenalidomide-dexamethasone, on CD38 levels of multiple myeloma cells and nontumor immune cells in the GEN501 study (daratumumab monotherapy) and the GEN503 study (daratumumab combined with lenalidomide-dexamethasone). In vitro assays were also performed.Results: In both trials, daratumumab reduced CD38 expression on multiple myeloma cells within hours after starting the first infusion, regardless of depth and duration of the response. In addition, CD38 expression on nontumor immune cells, including natural killer cells, T cells, B cells, and monocytes, was also reduced irrespective of alterations in their absolute numbers during therapy. In-depth analyses revealed that CD38 levels of multiple myeloma cells were only reduced in the presence of complement or effector cells, suggesting that the rapid elimination of CD38high multiple myeloma cells can contribute to CD38 reduction. In addition, we discovered that daratumumab–CD38 complexes and accompanying cell membrane were actively transferred from multiple myeloma cells to monocytes and granulocytes. This process of trogocytosis was also associated with reduced surface levels of some other membrane proteins, including CD49d, CD56, and CD138.Conclusions: Daratumumab rapidly reduced CD38 expression levels, at least in part, through trogocytosis. Importantly, all these effects also occurred in patients with deep and durable responses, thus excluding CD38 reduction alone as a mechanism of daratumumab resistance.The trials were registered at www.clinicaltrials.gov as NCT00574288 (GEN501) and NCT1615029 (GEN503). Clin Cancer Res; 23(24); 7498–511. ©2017 AACR.
EClinicalMedicine, Jul 1, 2023
Daratumumab-mediated CD38 reduction on NK cells is abrogated by depleting monocytes from PBMCs.
Supplemental Methods, Supplementary Tables, Supplementary Figure Legends
Transfer of surface membrane from UM9 cells to monocytes.
Loss of CD38 from the MM cell membrane is associated with reduced CDC and ADCC
Daratumumab-mediated CD38 reduction of MM cells in the presence of PBMCs as shown by Western blot... more Daratumumab-mediated CD38 reduction of MM cells in the presence of PBMCs as shown by Western blot analysis.
Daratumumab is transferred from UM9 cells to monocytes.
Monocytes take up AF488-labeled daratumumab-CD38 complexes from PKH-26-stained UM9 cells.
Methods in molecular biology, 2011
Declaración de obra original Yo declaro lo siguiente: He leído el Acuerdo 035 de 2003 del Consejo... more Declaración de obra original Yo declaro lo siguiente: He leído el Acuerdo 035 de 2003 del Consejo Académico de la Universidad Nacional. «Reglamento sobre propiedad intelectual» y la Normatividad Nacional relacionada al respeto de los derechos de autor. Esta disertación representa mi trabajo original, excepto donde he reconocido las ideas, las palabras, o materiales de otros autores. Cuando se han presentado ideas o palabras de otros autores en esta disertación, he realizado su respectivo reconocimiento aplicando correctamente los esquemas de citas y referencias bibliográficas en el estilo requerido. He obtenido el permiso del autor o editor para incluir cualquier material con derechos de autor (por ejemplo, tablas, figuras, instrumentos de encuesta o grandes porciones de texto). Por último, he sometido esta disertación a la herramienta de integridad académica, definida por la universidad.
Molecular & Cellular Proteomics, May 1, 2020
Acute myeloid leukemia (AML) is a clonal disorder arising from hematopoietic myeloid progenitors.... more Acute myeloid leukemia (AML) is a clonal disorder arising from hematopoietic myeloid progenitors. Aberrantly activated tyrosine kinases (TK) are involved in leukemogenesis and are associated with poor treatment outcome. Kinase inhibitor (KI) treatment has shown promise in improving patient outcome in AML. However, inhibitor selection for patients is suboptimal. In a preclinical effort to address KI selection, we analyzed a panel of 16 AML cell lines using phosphotyrosine (pY) enrichment-based, label-free phosphoproteomics. The Integrative Inferred Kinase Activity (INKA) algorithm was used to identify hyperphosphorylated, active kinases as candidate for KI treatment, and efficacy of selected KIs was tested. Heterogeneous signaling was observed with between 241 and 2764 phosphopeptides detected per cell line. Of 4853 identified phosphopeptides with 4229 phosphosites, 4459 phosphopeptides (4430 pY) were linked to 3605 class I sites (3525 pY). INKA analysis in single cell lines successfully pinpointed driver kinases (PDGFRA, JAK2, KIT and FLT3) corresponding with activating mutations present in these cell lines. Furthermore, potential receptor tyrosine kinase (RTK) drivers, undetected by standard molecular analyses, were identified in four cell lines (FGFR1 in KG-1 and KG-1a, PDGFRA in Kasumi-3, and FLT3 in MM6). These cell lines proved highly sensitive to specific KIs. Six AML cell lines without a clear RTK driver showed evidence of MAPK1/3 activation, indicative of the presence of activating upstream RAS mutations. Importantly, FLT3 phosphorylation was demonstrated in two clinical AML samples with a FLT3 internal tandem duplication (ITD) mutation. Our data show the potential of pY-phosphoproteomics and INKA analysis to provide insight in AML TK signaling and identify hyperactive kinases as potential targets for treatment in AML cell lines. These results warrant future investigation of clinical samples to further our understanding of TK phosphorylation in relation to clinical response in the individual patient.
Purpose Despite the encouraging results of bortezomib (BTZ) in hematologic malignancies to date, ... more Purpose Despite the encouraging results of bortezomib (BTZ) in hematologic malignancies to date, resistance to BTZ may be a limiting factor to its efficacy. Hence, parameters that may identify responsiveness to BTZ-containing therapy will be of clinical interest. Recently, we reported that higher ratios of immunoproteasome over constitutive proteasome protein expression in pediatric ALL and AML leukemia cells at diagnosis were an accountable factor for ex vivo sensitivity to proteasome inhibitors (Niewerth et al, Haematologica 2013). Here we explored whether this parameter was associated with response to BTZ in first relapsed and refractory pediatric acute leukemia patients treated in phase II clinical trials of BTZ combined with re-induction chemotherapy for pediatric ALL (COG-AALL07P1) and pediatric AML (COG-AAML07P1). Methods Protein expression levels of constitutive- β5 and β1, and immunoproteasome subunits β5i and β1i were determined by Western blot analysis in 61 acute leukemia patient samples (ALL n=47, AML n=14) obtained before BTZ-containing reinduction therapy. In addition, β5 and β5i proteasome catalytic activities were measured in 14 ALL and 13 AML samples prior to treatment. Lastly, NF-ĸB activity was determined by p65 ELISA in nuclear extracts of PBMCs before and 24h after BTZ treatment. Results In pre-treatment samples, expression ratios of both β5i/β5 and β1i/β1 were significantly higher in ALL cells than in AML cells (P=0.049 and P=0.002, respectively). Ratios of both β5i/β5 and β1i/β1 were significantly higher in patients that reached complete remission (CR; n=39) compared to patients that did not reach CR (n=22) (P=0.009 for β5i/β5, P=0.025 for β1i/β1). Moreover, increased ratios of β5i/β5 catalytic activity were observed in pre-treatment ALL+AML samples that reached CR compared to those that did not reach CR (P=0.078). Proteasome activity ratios correlated significantly with proteasome expression ratios (R=0.55 P=0.005). Notably, NF-ĸB activity was similar in both groups and was suppressed after BTZ treatment, being most pronounced in the pre-B ALL patients that achieved CR (average decrease: 47% p=0.05). Conclusion These results suggest that a higher ratio of immuno/constitutive proteasome in pretreatment ALL and AML cells is an accountable factor for the clinical response to BTZ. These results warrant further investigation to establish a biomarker that can be used for selecting relapsed pediatric acute leukemia patients eligible for BTZ-containing reinduction treatment. This study was sponsored by KiKa (Children Cancer-free-GJLK), Millennium pharmaceuticals (TMH), and NIH-K23-CA113775 (TMH) Citation Format: Denise Niewerth, Gertjan J.L. Kaspers, Gerrit Jansen, Johan van Meerloo, Sonja Zweegman, Gaye Jenkins, James A. Whitlock, Stephen P. Hunger, Xiaomin Lu, Jacqueline Cloos, Terzah M. Horton. Ratios of immunoproteasome over constitutive proteasome expression are an indicator for sensitivity to bortezomib-containing reinduction chemotherapy in pediatric relapsed ALL and AML. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-169. doi:10.1158/1538-7445.AM2014-LB-169
Journal of Hematology & Oncology, Jan 13, 2014
Background: Despite encouraging results with the proteasome inhibitor bortezomib in the treatment... more Background: Despite encouraging results with the proteasome inhibitor bortezomib in the treatment of hematologic malignancies, emergence of resistance can limit its efficacy, hence calling for novel strategies to overcome bortezomib-resistance. We previously showed that bortezomib-resistant human leukemia cell lines expressed significantly lower levels of immunoproteasome at the expense of constitutive proteasomes, which harbored point mutations in exon 2 of the PSMB5 gene encoding the β5 subunit. Here we investigated whether up-regulation of immunoproteasomes by exposure to interferon-γ restores sensitivity to bortezomib in myeloma and leukemia cell lines with acquired resistance to bortezomib. Methods: RPMI-8226 myeloma, THP1 monocytic/macrophage and CCRF-CEM (T) parental cells and sub lines with acquired resistance to bortezomib were exposed to Interferon-γ for 24-48 h where after the effects on proteasome subunit expression and activity were measured, next to sensitivity measurements to proteasome inhibitors bortezomib, carfilzomib, and the immunoproteasome selective inhibitor ONX 0914. At last, siRNA knockdown experiments of β5i and β1i were performed to identify the contribution of these subunits to sensitivity to proteasome inhibition. Statistical significance of the differences were determined using the Mann-Whitney U test. Results: Interferon-γ exposure markedly increased immunoproteasome subunit mRNA to a significantly higher level in bortezomib-resistant cells (up to 30-fold, 10-fold, and 6-fold, in β1i, β5i, and β2i, respectively) than in parental cells. These increases were paralleled by elevated immunoproteasome protein levels and catalytic activity, as well as HLA class-I. Moreover, interferon-γ exposure reinforced sensitization of bortezomib-resistant tumor cells to bortezomib and carfilzomib, but most prominently to ONX 0914, as confirmed by cell growth inhibition studies, proteasome inhibitor-induced apoptosis, activation of PARP cleavage and accumulation of polyubiquitinated proteins. This sensitization was abrogated by siRNA silencing of β5i but not by β1i silencing, prior to pulse exposure to interferon-γ. Conclusion: Downregulation of β5i subunit expression is a major determinant in acquisition of bortezomib-resistance and enhancement of its proteasomal assembly after induction by interferon-γ facilitates restoration of sensitivity in bortezomib-resistant leukemia cells towards bortezomib and next generation (immuno) proteasome inhibitors.
Cells, Mar 17, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Hematology & Oncology, Sep 6, 2016
Background: Drug combinations of the proteasome inhibitor bortezomib with cytotoxic chemotherapy ... more Background: Drug combinations of the proteasome inhibitor bortezomib with cytotoxic chemotherapy are currently evaluated in phase 2 and 3 trials for the treatment of paediatric acute myeloid leukaemia (AML) and acute lymphocytic leukaemia (ALL). Methods: We investigated whether expression ratios of immunoproteasome to constitutive proteasome in leukaemic cells correlated with response to bortezomib-containing re-induction chemotherapy in patients with relapsed and refractory acute leukaemia, enrolled in two Children's Oncology Group phase 2 trials of bortezomib for ALL (COG-AALL07P1) and AML (COG-AAML07P1). Expression of proteasome subunits was examined in 72 patient samples (ALL n = 60, AML n = 12) obtained before start of therapy. Statistical significance between groups was determined by Mann-Whitney U test. Results: Ratios of immunoproteasome to constitutive proteasome subunit expression were significantly higher in pre-B ALL cells than in AML cells for both β5i/β5 and β1i/β1 subunits (p = 0.004 and p < 0.001). These ratios correlated with therapy response in AML patients; β1i/β1 ratios were significantly higher (p = 0.028) between patients who did (n = 4) and did not reach complete remission (CR) (n = 8), although for β5i/β5 ratios, this did not reach significance. For ALL patients, the subunit ratios were also higher for patients who showed a good early response to therapy but this relation was not statistically significant. Overall, for this study, the patients were treated with combination therapy, so response was not only attributed to proteasome inhibition. Moreover, the leukaemic blast cells were not purified for these samples. Conclusions: These first ex vivo results encourage further studies into relative proteasome subunit expression to improve proteasome inhibition-containing therapy and as a potential indicator of bortezomib response in acute leukaemia.
Cancer and Metastasis Reviews, Oct 25, 2017
The clinical efficacy of proteasome inhibitors in the treatment of multiple myeloma has encourage... more The clinical efficacy of proteasome inhibitors in the treatment of multiple myeloma has encouraged application of proteasome inhibitor containing therapeutic interventions in (pediatric) acute leukemia. Here, we summarize the positioning of bortezomib, as first-generation proteasome inhibitor, and second-generation proteasome inhibitors in leukemia treatment from a preclinical and clinical perspective. Potential markers for proteasome inhibitor sensitivity and/or resistance emerging from leukemia cell line models and clinical sample studies will be discussed focusing on the role of immunoproteasome and constitutive proteasome (subunit) expression, PSMB5 mutations, and alternative mechanisms of overcoming proteolytic stress.
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Papers by Johan van Meerloo