Prognostic Significance of Cereblon Expression in Patients With Multiple Myeloma

Targeting the ubiquitin pathway in lymphoid malignancies

Ubiquitination and related cellular processes control a variety of aspects in human cell biology, and defects in these processes contribute to multiple illnesses. In recent decades, our knowledge about the pathological role of ubiquitination in lymphoid cancers and therapeutic strategies to target the modified ubiquitination system has evolved tremendously. Here we review the altered signalling mechanisms mediated by the aberrant expression of cancer-associated E2s/E3s and deubiquitinating enzymes (DUBs), which result in the hyperactivation of oncoproteins or the frequently allied downregulation of tumour suppressors. We discuss recent highlights pertaining to the several different therapeutic interventions which are currently being evaluated to effectively block abnormal ubiquitin-proteasome pathway and the use of heterobifunctional molecules which recruit the ubiquitination system to degrade or stabilize non-cognate substrates. This review aids in comprehension of ubiquitination aberrance in lymphoid cancers and current targeting strategies and elicits further investigations to deeply understand the link between cellular ubiquitination and lymphoid pathogenesis as well as to ameliorate corresponding treatment interventions.

Bone Marrow Microenvironment Interplay and Current Clinical Practice in Multiple Myeloma: A Review of the Balkan Myeloma Study Group

The course of multiple myeloma (MM) is influenced by a variety of factors, including the specificity of the tumour microenvironment (TME). The aim of this review is to provide insight into the interplay of treatment modalities used in the current clinical practice and TME. Bortezomib-based triplets are the standard for MM first-line treatment. Bortezomib is a proteasome inhibitor (PI) which inhibits the nuclear factor kappa B (NF-κB) pathway. However, bortezomib is decreasing the expression of chemokine receptor CXCR4 as well, possibly leading to the escape of extramedullary disease. Immunomodulatory drugs (IMiDs), lenalidomide, and pomalidomide downregulate regulatory T cells (Tregs). Daratumumab, anti-cluster of differentiation 38 (anti-CD38) monoclonal antibody (MoAb), downregulates Tregs CD38+. Bisphosphonates inhibit osteoclasts and angiogenesis. Sustained suppression of bone resorption characterises the activity of MoAb denosumab. The plerixafor, used in the process of stem cell mobilisation and harvesting, block the interaction of chemokine receptors CXCR4-CXCL12, leading to disruption of MM cells’ interaction with the TME, and mobilisation into the circulation. The introduction of several T-cell-based immunotherapeutic modalities, such as chimeric-antigen-receptor-transduced T cells (CAR T cells) and bispecific antibodies, represents a new perspective in MM treatment affecting TME immune evasion. The optimal treatment approach to MM patients should be adjusted to all aspects of the individual profile including the TME niche.

Prediction Model for Cereblon Expression in Bone Marrow Plasma Cells Based on Blood Markers in Multiple Myeloma Patients

Background

Cereblon (CRBN) is a direct target of immunomodulatory drugs (IMiDs) and is known to be sensitive and responsive to IMiD therapy. We evaluated CRBN expression in bone marrow plasma cells and analyzed whether CRBN expression was associated with multiple myeloma prognosis. Lastly, we developed a nomogram model for predicting high CRBN expression based on clinically significant blood markers.

Methods

We evaluated 143 multiple myeloma patients (internal dataset) who underwent bone marrow examinations. For evaluating the prognostic ability of the nomogram model, two external cohorts (235 patients in external dataset 1 and 156 patients in external dataset 2) were analyzed. The expression of CRBN in bone marrow aspirate samples was evaluated using immunohistochemistry. High CRBN expression was defined as the study-defined H-score ≥6.

Results

In the high CRBN group, the median progression-free survival (PFS) and overall survival (OS) of patients receiving the IMiD-based therapy and non-IMiD therapy were 29 and 10 months for PFS, and NR (not reached) and 54 months for OS, respectively. IMiD-based therapy was significantly associated with better PFS and OS outcomes. High CRBN expression was independently predicted by female sex, high serum free-light chain (FLC) ratio, higher serum M-protein level, and higher β2-microglobulin level. Based on these results, we constructed a new nomogram model to predict high CRBN expression and the effectiveness of IMiD therapy in multiple myeloma.

Conclusion

This nomogram could improve the prognostic evaluation of myeloma patients exhibiting high CRBN expression treated with IMiD therapy and might help provide personalized treatment strategies to clinicians.

Cereblon expression is a prognostic marker in newly diagnosed POEMS syndrome treated with lenalidomide plus dexamethasone

POEMS syndrome is a rare plasma cell disorder. Lenalidomide has recently emerged as a therapeutic option for POEMS syndrome. Cereblon has been identified as the direct target of lenalidomide, and high cereblon expression is associated with better response and outcome to lenalidomide therapy in multiple myeloma patients. Here, we analyzed the predictive value of cereblon, IKZF1, and IKZF3 in CD138⁺ selected plasma cells from forty-one newly diagnosed POEMS syndrome patients treated with lenalidomide in combination with dexamethasone at both gene and protein levels. We found that patients with high cereblon expression tended to achieve better hematologic response compared to those with low expression (p = 0.024 for gene expression; p = 0.01 for protein expression). Multivariate Cox regression analysis revealed high cereblon mRNA expression as an independent prognostic marker for longer progression-free survival (hazard ratio 0.542; 95% CI 0.337-0.871; p = 0.011). In conclusion, our results emphasized the role of cereblon mRNA expression as a unique biomarker for predicting the clinical response and outcome of lenalidomide-based therapy in newly diagnosed POEMS syndrome patients.

Genotoxic potential of a novel PDE-4B inhibitor Apremilast by chromosomal aberration and micronucleus assay in mice

Objective

Researchers have confirmed that chronic administration of drugs at high doses causes genotoxicity which serve as first step in development of cancers. Apremilast, a phosphodiesterase-4 inhibitor is Food and Drug Administration (FDA) approved drug for Psoriatic Arthritis. The present study designed to conduct genotoxicity testing using the genotoxic study which give simple, sensitive, economical and fast tools for the assessment of damage of genetic material.

Methods

To conduct genotoxicity study of Apremilast, 60 Swiss albino male mice divided into 6 groups (n = 10). Group1 served as a normal control group without any treatment, Group 2 treated as a disease control and administered with cyclophosphamide 40 mg/kg, IP. Group 3, 4, 5 and 6 treated as test groups and received 10, 20, 40 and 80 mg/kg/day Apremilast respectively. The total duration of study was 13 weeks. At termination day animals were sacrificed and chromosomal aberration assay (BMCAA) and micronucleus assay (BMMNA) were performed to know the genotoxicity potential of Apremilast.

Results

The results indicates significant rise in chromosomal aberrations (CA) frequency in bone marrow cells and decrease in the MI of the disease control animals as well as Apremilast treated groups. Further significant (p < 0.001; p < 0.0001) increase in score of micronucleated polychromatic erythrocytes (MNPCEs) and percentage of micronucleated PCEs per 1000 PCEs and decrease in the ratio of polychromatic/normochromatic erythrocytes (PCE/NCE) was observed in micronucleus assay. Genotoxic effect increases with the increase of Apremilast dose. Conclusion: Finding of present indicates that Apremilast shows genotoxic potential on high administration although further detailed toxicity studies required for confirmations.

Cereblon (CRBN) gene polymorphisms predict clinical response and progression-free survival in relapsed/refractory multiple myeloma patients treated with lenalidomide: a pharmacogenetic study from the IMMEnSE consortium

Cereblon (CRBN) is crucial for antiproliferative and immunomodulatory properties of immunomodulatory drugs. The objective of this study was to verify whether germline single nucleotide polymorphisms (SNPs) in the CRBN gene may influence response to lenalidomide in multiple myeloma (MM). Fourteen tagging SNPs covering the genetic variability in the CRBN gene region were genotyped in 167 Polish patients with refractory/relapsed MM treated with lenalidomide-based regimens. We found that carriers of minor alleles of two studied CRBN SNPs rs1714327G > C (OR = 0.26; 95% CI = 0.1-0.67; p = .0055, Bonferroni corrected p = .033) and rs1705814T > C (OR = 0.22; 95% CI = 0.07-0.65; p = .0063, Bonferroni corrected p = .037) were significantly associated with lower probability of achievement at least partial remission while treated with lenalidomide-based regimens, using the dominant inheritance model. Moreover, one of these SNPs, namely rs1705814T > C, was correlated with shorter progression-free survival (HR = 2.49; 95%CI = 1.31-4.74, p = .0054, Bonferroni corrected p = .033). It is suggested that selected germline CRBN allelic variants (rs1714327G > C and rs1705814T > C) affect lenalidomide efficacy in patients with relapsed/refractory MM.

Acquired Resistance to BET-PROTACs (Proteolysis-Targeting Chimeras) Caused by Genomic Alterations in Core Components of E3 Ligase Complexes

Proteolysis-targeting chimeras (PROTAC) are bifunctional molecules that hijack endogenous E3 ubiquitin ligases to induce ubiquitination and subsequent degradation of protein of interest. Recently, it has been shown that PROTACs with robust in vitro and in vivo activities and, in some cases, drug-like pharmaceutical properties can be generated using small-molecule ligands for the E3 ligases VHL and CRBN. These findings stoked tremendous enthusiasm on using PROTACs for therapeutics development. Innate and acquired drug resistance often underlies therapeutic failures, particularly for cancer therapy. With the PROTAC technology progressing rapidly toward therapeutic applications, it would be important to understand whether and how resistance to these novel agents may emerge. Using BET-PROTACs as a model system, we demonstrate that resistance to both VHL- and CRBN-based PROTACs can occur in cancer cells following chronic treatment. However, unlike what was often observed for many targeted therapeutics, resistance to BET-PROTACs did not result from secondary mutations that affect compound binding to the target. In contrast, acquired resistance to both VHL- and CRBN-based BET-PROTACs was primarily caused by genomic alterations that compromise core components of the relevant E3 ligase complexes.

Lenalidomide combined with low-dose cyclophosphamide and prednisone modulates Ikaros and Aiolos in lymphocytes, resulting in immunostimulatory effects in lenalidomide-refractory multiple myeloma patients

We recently showed that the outcome of multiple myeloma (MM) patients treated in the REPEAT study (evaluation of lenalidomide combined with low-dose cyclophosphamide and prednisone (REP) in lenalidomide-refractory MM) was markedly better than what has been described with cyclophosphamide-prednisone alone. The outcome with REP was not associated with plasma cell Cereblon expression levels, suggesting that the effect of REP treatment may involve mechanisms independent of plasma cell Cereblon-mediated direct anti-tumor activity. We therefore hypothesized that immunomodulatory effects contribute to the anti-MM activity of REP treatment, rather than plasma cell Cereblon-mediated effects. Consequently, we now characterized the effect of REP treatment on immune cell subsets in peripheral blood samples collected on day 1 and 14 of cycle 1, as well as on day 1 of cycle 2. We observed a significant mid-cycle decrease in the Cereblon substrate proteins Ikaros and Aiolos in diverse lymphocyte subsets, which was paralleled by an increase in T-cell activation. These effects were restored to baseline at day one of the second cycle, one week after lenalidomide interruption. In vitro, lenalidomide enhanced peripheral blood mononuclear cell-mediated killing of both lenalidomide-sensitive and lenalidomide-resistant MM cells in a co-culture system. These results indicate that the Cereblon-mediated immunomodulatory properties of lenalidomide are maintained in lenalidomide-refractory MM patients and may contribute to immune-mediated killing of MM cells. Therefore, combining lenalidomide with other drugs can have potent effects through immunomodulation, even in patients considered to be lenalidomide-refractory.

A novel nano-immunoassay method for quantification of proteins from CD138-purified myeloma cells: biological and clinical utility

Protein analysis in bone marrow samples from patients with multiple myeloma has been limited by the low concentration of proteins obtained after CD138⁺ cell selection. A novel approach based on capillary nano-immunoassay could make it possible to quantify dozens of proteins from each myeloma sample in an automated manner. Here we present a method for the accurate and robust quantification of the expression of multiple proteins extracted from CD138-purified multiple myeloma samples frozen in RLT Plus buffer, which is commonly used for nucleic acid preservation and isolation. Additionally, the biological and clinical value of this analysis for a panel of 12 proteins essential to the pathogenesis of multiple myeloma was evaluated in 63 patients with newly diagnosed multiple myeloma. The analysis of the prognostic impact of CRBN/Cereblon and IKZF1/Ikaros mRNA/protein showed that only the protein levels were able to predict progression-free survival of patients; mRNA levels were not associated with prognosis. Interestingly, high levels of Cereblon and Ikaros proteins were associated with longer progression-free survival only in patients who received immunomodulatory drugs and not in those treated with other drugs. In conclusion, the capillary nano-immunoassay platform provides a novel opportunity for automated quantification of the expression of more than 20 proteins in CD138⁺ primary multiple myeloma samples.

Analysis of Global Gene Expression Profiles

DNA microarrays have considerably helped to improve the understanding of biological processes and diseases including multiple myeloma (MM). GEP analyses have been successful to classify MM, define risk, identify therapeutic targets, predict treatment response, and understand drug resistance.This generated large amounts of publicly available data that could benefit from easy-to-use bioinformatics resources to analyze them. Here we present easy-to-use and open-access bioinformatics tools to extract and visualize the most prominent information from GEP data.

Cereblon: A Protein Crucial to the Multiple Functions of Immunomodulatory Drugs as well as Cell Metabolism and Disease Generation

It is well known that cereblon is a key protein in autosomal recessive nonsyndromic mental retardation. Studies have reported that it has an intermediary role in helping immunomodulatory drugs perform their immunomodulatory and tumoricidal effects. In addition, cereblon also regulates the expression, assembly, and activities of other special proteins related to cell proliferation and metabolism, resulting in the occurrence and development of metabolic diseases. This review details the multiple functions of cereblon and the underlying mechanisms. We also put forward some unsolved problems, including the intrinsic mechanism of cereblon function and the possible regulatory mechanisms of its expression.