Lenalidomide for treatment of myelodysplastic syndromes: current status and future directions

Improved Side Effect Profile of Alternate-Day Dosing of Lenalidomide

Myelodysplastic syndrome (MDS) is a heterogeneous hematological condition associated with cytopenia, inadequate blood cell synthesis, and the risk of developing acute myeloid leukemia (AML). Patients are divided into risk groups according to the International Prognostic Scoring System (IPSS) to help direct therapy. Allogeneic stem cell transplantation, despite its limitations, is curative. Medical management, such as the use of lenalidomide, has potential benefits but can cause adverse effects that require dose regimen modification. Lenalidomide is approved for low-risk MDS with 5q deletion (5q- MDS). In this case study, a 79-year-old woman with 5q- MDS was switched from a daily regimen to an alternate-day lenalidomide dose schedule to achieve complete remission with fewer adverse effects. The management of hematological toxicity and the mechanisms of action of lenalidomide are discussed. We recommend individualized treatment strategies and additional research to improve MDS management.

Novel Molecular Mechanism of Lenalidomide in Myeloid Malignancies Independent of Deletion of Chromosome 5q

Lenalidomide as well as other immunomodulatory drugs (IMiDs) have achieved clinical efficacies in certain sub-types of hematologic malignancies, such as multiple myeloma, lower-risk myelodysplastic syndromes (MDS) with a single deletion of chromosome 5q (del(5q)) and others. Despite superior clinical response to lenalidomide in hematologic malignancies, relapse and resistance remains a problem in IMiD-based therapy. The last ten years have witnessed the discovery of novel molecular mechanism of IMiD-based anti-tumor therapy. IMiDs bind human cereblon (CRBN), the substrate receptor of the CRL4 E3 ubiquitin ligase complex. Binding of CRBN with IMiDs leads to degradation of the Ikaros family zinc finger proteins 1 and 3 (IKZF1 and IKZF3) and casein kinase 1 alpha. We have found that lenalidomide-mediated degradation of IKZF1 leads to activation of the G protein-coupled receptor 68 (GPR68)/calcium/calpain pro-apoptotic pathway and inhibition of the regulator of calcineurin 1 (RCAN1)/calcineurin pro-survival pathway in MDS and acute myeloid leukemia (AML). Calcineurin inhibitor Cyclosporin-A potentiates the anti-leukemia activity of lenalidomide in MDS/AML with or without del(5q). These findings broaden the therapeutic potential of IMiDs. This review summarizes novel molecular mechanism of lenalidomide in myeloid malignancies, especially without del(5q), in the hope to highlight novel therapeutic targets.

Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

[Lenalidomide nephrotoxicity]

The introduction of lenalidomide into the therapeutic arsenal of hematologic malignancies has represented an important step forward in the management of multiple myeloma. However, its use is associated with several toxicities including kidney injury. The present review examines the drug's pharmacokinetics, discusses the main adverse renal effects that are associated with lenalidomide treatment, and makes recommendations for dosage adjustment in patients with underlying renal impairment.

A case of DRESS (drug reaction with eosinophilia and systemic symptoms) with acute interstitial nephritis secondary to lenalidomide

Acute kidney injury is commonly observed in patients with multiple myeloma and other plasma cell dyscrasias. The pathophysiologic causes, however, are varied. We report a case of a severe ‘drug reaction with eosinophilia and systemic symptoms’ syndrome associated with acute interstitial nephritis in a patient with multiple myeloma likely related to the administration of lenalidomide. This disease entity requires prompt recognition and cessation of the offending drug and often treatment with high-dose corticosteroids.

Mechanism of immunomodulatory drugs' action in the treatment of multiple myeloma

Although immunomodulatory drugs (IMiDs), such as thalidomide, lenalidomide, and pomalidomide, are widely used in the treatment of multiple myeloma (MM), the molecular mechanism of IMiDs' action is largely unknown. In this review, we will summarize recent advances in the application of IMiDs in MM cancer treatment as well as their effects on immunomodulatory activities, anti-angiogenic activities, intervention of cell surface adhesion molecules between myeloma cells and bone marrow stromal cells, anti-inflammatory activities, anti-proliferation, pro-apoptotic effects, cell cycle arrest, and inhibition of cell migration and metastasis. In addition, the potential IMiDs' target protein, IMiDs' target protein's functional role, and the potential molecular mechanisms of IMiDs resistance will be discussed. We wish, by presentation of our naive discussion, that this review article will facilitate further investigation in these fields.

Current therapy of myelodysplastic syndromes

After being a neglected and poorly-understood disorder for many years, there has been a recent explosion of data regarding the complex pathogenesis of myelodysplastic syndromes (MDS). On the therapeutic front, the approval of azacitidine, decitabine, and lenalidomide in the last decade was a major breakthrough. Nonetheless, the responses to these agents are limited and most patients progress within 2 years. Allogeneic stem cell transplantation remains the only potentially curative therapy, but it is associated with significant toxicity and limited efficacy. Lack or loss of response after standard therapies is associated with dismal outcomes. Many unanswered questions remain regarding the optimal use of current therapies including patient selection, response prediction, therapy sequencing and combinations, and management of resistance. It is hoped that the improved understanding of the underpinnings of the complex mechanisms of pathogenesis will be translated into novel therapeutic approaches and better prognostic/predictive tools that would facilitate accurate risk-adaptive therapy.

Combined treatment with lenalidomide and epoetin alfa in lower-risk patients with myelodysplastic syndrome

The erythropoietic effects of lenalidomide are cytokine dependent, suggesting that the erythroid hematologic improvement (HI-E) rate may be augmented by combined treatment (CT) with recombinant human erythropoietin (rhu-EPO) in myelodysplastic syndrome (MDS). In the present study, we explored the benefits of CT and the relationship between lenalidomide pharmacokinetics and hematologic toxicity in transfusion-dependent patients with low- to intermediate-1–risk MDS who failed prior rhu-EPO. In stage I, patients received 10 or 15 mg/d of lenalidomide monotherapy. At week 16, erythroid nonresponders (NRs) were eligible for CT with rhu-EPO 40 000 U/wk. Among 39 patients, HI-E response rate to monotherapy was 86% (6 of 7) in del(5q) and 25% (8 of 32) in non-del(5q) patients (10 mg, 17.7%; 15 mg, 33.3%). Twenty-three patients proceeded to CT, with 6 (26.0%) achieving HI-E. In 19 non-del(5q) patients, 4 (21.1%) showed HI-E. Mean baseline serum EPO in non-del(5q) patients was lower in monotherapy and CT responders than in NR (not statistically significant). Thrombocytopenia was significantly correlated with lenalidomide area under the plasma concentration-time curve (P = .0015), but severity of myelosuppression did not. The benefits of lenalidomide plus rhu-EPO are currently under investigation in a phase 3 Eastern Cooperative Oncology Group (ECOG)–sponsored intergroup study. This study is registered at www.clinicaltrials.gov as NCT00910858.

A new recurrent chromosomal translocation t(3;11)(q13;q14) in myelodysplastic syndromes associated with overexpression of the ILDR1 gene

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases characterized by ineffective hematopoiesis and an increased risk of evolution to acute myeloid leukemia (AML). In this study, the combination of conventional cytogenetic, FISH studies and molecular techniques allowed us to unveil a novel recurrent t(3;11)(q13;q14) causing the overexpression of the immunoglobulin-like domain-containing receptor (ILDR1) gene. The analysis of gene expression was extended to Refractory Anemia (RA) and Refractory Anemia with excess blasts (RAEB) cases revealing ILDR1 overexpression in 36% of RAEB subgroup. The biological implications of the ILDR1 overexpression in MDS pathogenesis and its potential prognostic significance should be further investigated.

Important genes in the pathogenesis of 5q- syndrome and their connection with ribosomal stress and the innate immune system pathway

Myelodysplastic syndrome (MDS) with interstitial deletion of a segment of the long arm of chromosome 5q [del(5q)] is characterized by bone marrow erythroid hyperplasia, atypical megakaryocytes, thrombocythemia, refractory anemia, and low risk of progression to acute myeloid leukemia (AML) compared with other types of MDS. The long arm of chromosome 5 contains two distinct commonly deleted regions (CDRs). The more distal CDR lies in 5q33.1 and contains 40 protein-coding genes and genes coding microRNAs (miR-143, miR-145). In 5q-syndrome one allele is deleted that accounts for haploinsufficiency of these genes. The mechanism of erythroid failure appears to involve the decreased expression of the ribosomal protein S14 (RPS14) gene and the upregulation of the p53 pathway by ribosomal stress. Friend leukemia virus integration 1 (Fli1) is one of the target genes of miR145. Increased Fli1 expression enables effective megakaryopoiesis in 5q-syndrome.

Oncolytic virotherapy for hematological malignancies

Hematological malignancies such as leukemias, lymphomas, multiple myeloma (MM), and the myelodysplastic syndromes (MDSs) primarily affect adults and are difficult to treat. For high-risk disease, hematopoietic stem cell transplant (HCT) can be used. However, in the setting of autologous HCT, relapse due to contamination of the autograft with cancer cells remains a major challenge. Ex vivo manipulations of the autograft to purge cancer cells using chemotherapies and toxins have been attempted. Because these past strategies lack specificity for malignant cells and often impair the normal hematopoietic stem and progenitor cells, prior efforts to ex vivo purge autografts have resulted in prolonged cytopenias and graft failure. The ideal ex vivo purging agent would selectively target the contaminating cancer cells while spare normal stem and progenitor cells and would be applied quickly without toxicities to the recipient. One agent which meets these criteria is oncolytic viruses. This paper details experimental progress with reovirus, myxoma virus, measles virus, vesicular stomatitis virus, coxsackievirus, and vaccinia virus as well as requirements for translation of these results to the clinic.

Hydrophilic residues are crucial for ribosomal protein L11 (RPL11) interaction with zinc finger domain of MDM2 and p53 protein activation

Ribosomal protein L11 (RPL11) has been shown to activate p53 by binding to MDM2 and negating its p53 suppression activity in response to ribosomal stress. Although a mutation at Cys-305 within the zinc finger domain of MDM2 has been shown to drastically impair MDM2 interaction with RPL11 and thus escapes the inhibition by this ribosomal protein, it still remains elusive whether RPL11 inactivates MDM2 via direct action on this zinc finger domain and what is the chemical nature of this specific interaction. To define the roles of the MDM2 zinc finger in association with RPL11, we conducted hydrogen-deuterium exchange mass spectrometry, computational modeling, circular dichroism, and mutational analyses of the zinc finger domain of MDM2 and human RPL11. Our study reveals that RPL11 forms a stable complex with MDM2 in vitro through direct contact with its zinc finger. This binding is disrupted by single mutations of non-cysteine amino acids within the zinc finger domain of MDM2. Basic residues in RPL11 are crucial for the stable binding and RPL11 suppression of MDM2 activity toward p53. These results provide the first line of evidence for the specific interaction between RPL11 and the zinc finger of MDM2 via hydrophilic residues as well as a molecular foundation for better understanding RPL11 inhibition of MDM2 function.

Biology and treatment of the 5q- syndrome

The 5q- syndrome is a unique subtype of myelodysplastic syndromes typified by a relatively indolent course and responsiveness to lenalidomide. Here, we review the salient biologic features of this disease. Hemizygous deletion of a segment of chromosome 5q is believed to be the disease-initiating event. Recent molecular techniques have isolated the common deleted region and characterized key candidate genes contributing to the disease phenotype. Gene-specific RNA interference strategies revealed that haplo-insufficiency for the RPS14 gene, which encodes a ribosomal protein, is a critical effector of the p53-dependent erythroid hypoplasia and apoptotic loss of erythroid precursors. Disease-specific sensitivity to lenalidomide results from the drug's inhibitory effect on two haplodeficient phosphatases, PP2Acα and CDC25c, which are coregulators of the G(2)/M checkpoint. Hyperphosphorylation of MDM2, as a result of inhibition of PP2A phosphatase activity, stabilizes MDM2, permitting p53 degradation and transition to G(2) arrest and clonal suppression. With the emerging data elucidating the pathogenesis of the 5q- syndrome and the success of clinical trials, a cohesive story connecting the biology and pharmacology associated with this subtype of myelodysplastic syndromes has emerged.

ESH-SIOG International Conference on Haematological Malignancies in the Elderly

The aging of the population has been associated with an increased incidence and prevalence of neoplastic diseases. The management of cancer in the older aged person involves novel clinical problems, including benefits and risks of treatment in individuals with reduced life expectancy and treatment tolerance. The European School of Hematology has convened the first conference on hematological malignancies in the elderly to explore the issues related to the diagnosis and the treatment of these conditions, and to provide a frame of reference for therapeutic decisions to practicing hematologists. The main themes of the conference, which was attended by hematologists and geriatricians from Europe and the Americas, included an operative definition of aging, the effectiveness and risks of antineoplastic treatment in the aged, and the management of common malignancies such as myelodysplasia, leukemia, myeloma and lymphomas.

Unraveling the molecular pathophysiology of myelodysplastic syndromes

Somatically acquired genetic abnormalities lead to the salient features that define myelodysplastic syndromes (MDS): clonal hematopoiesis, aberrant differentiation, peripheral cytopenias, and risk of progression to acute myeloid leukemia. Although specific karyotypic abnormalities have been linked to MDS for decades, more recent findings have demonstrated the importance of mutations within individual genes, focal alterations that are not apparent by standard cytogenetics, and aberrant epigenetic regulation of gene expression. The spectrum of genetic abnormalities in MDS implicates a wide range of molecular mechanisms in the pathogenesis of these disorders, including activation of tyrosine kinase signaling, genomic instability, impaired differentiation, altered ribosome function, and changes in the bone marrow microenvironment. Specific alterations present in individual patients with MDS may explain much of the heterogeneity in clinical phenotype associated with this disease and can predict prognosis and response to therapy. Elucidation of the full complement of genetic causes of MDS promises profound insight into the biology of the disease, improved classification and prognostic scoring schemes, and the potential for novel targeted therapies with molecular predictors of response.

Advances in the 5q- syndrome

The 5q- syndrome is the most distinct of all the myelodysplastic syndromes with a clear genotype/phenotype relationship. The significant progress made during recent years has been based on the determination of the commonly deleted region and the demonstration of haploinsufficiency for the ribosomal gene RPS14. The functional screening of all the genes in the commonly deleted region determined that RPS14 haploinsufficiency is the probable cause of the erythroid defect in the 5q- syndrome. A mouse model of the human 5q- syndrome has now been created by chromosomal engineering involving a large-scale deletion of the Cd74-Nid67 interval (containing RPS14). A variety of lines of evidence support the model of ribosomal deficiency causing p53 activation and defective erythropoiesis, including most notably the crossing of the "5q- mice" with p53-deficient mice, thereby ameliorating the erythroid progenitor defect. Emerging evidence supports the notion that the p53 activation observed in the mouse model may also apply to the human 5q- syndrome. Other mouse modeling data suggest that haploinsufficiency of the microRNA genes miR-145 and miR-146a may contribute to the thrombocytosis seen in the 5q- syndrome. Lenalidomide has become an established therapy for the 5q- syndrome, although its precise mode of action remains uncertain.

How much? How frequent? How long? A clinical guide to new therapies in myelodysplastic syndromes

Advances in the treatment of myelodysplastic syndromes (MDSs) over the last decade have given patients and their hematologists a multitude of treatment options. Therapeutic options now exist that reduce disease-related symptoms, improve quality of life, and alter the natural history of the disease. Three drugs are now specifically Food and Drug Administration-approved for treatment of MDS: (1) azacitidine, (2) decitabine, and (3) lenalidomide. Clinical results with each of these agents, plus results with immunosuppressive therapy, are reviewed to guide clinical decision making. Although each therapy has made a substantial impact in improving the care of patients with MDS, unfortunately MDS treatment in 2010 ultimately fails in most patients, but these therapies provide a foundation on which we can build to further improve outcomes.