Long-term transfusion independence in del(5q) MDS patients who discontinue lenalidomide

How I Manage Transplant Ineligible Patients with Myelodysplastic Neoplasms

Myelodysplastic neoplasms, formerly known as myelodysplastic syndromes (MDS), represent a group of clonal disorders characterized by a high degree of clinical and molecular heterogeneity, and an invariable tendency to progress to acute myeloid leukemia. MDS typically present in the elderly with cytopenias of different degrees and bone marrow dysplasia, the hallmarks of the disease. Allogeneic hematopoietic stem cell transplant is the sole curative approach to date. Nonetheless, given the disease’s demographics, only a minority of patients can benefit from this procedure. Currently used prognostic schemes such as the Revised International Prognostic Scoring System (R-IPSS), and most recently the molecular IPSS (IPSS-M), guide clinical management by dividing MDS into two big categories: lower- and higher-risk cases, based on a cut-off score of 3.5. The main clinical problem of the lower-risk group is represented by the management of cytopenias, whereas the prevention of secondary leukemia progression is the goal for the latter. Herein, we discuss the non-transplant treatment of MDS, focusing on current practice and available therapeutic options, while also presenting new investigational agents potentially entering the MDS therapeutic arsenal in the near future.

Development of luspatercept to treat ineffective erythropoiesis

Luspatercept (Reblozyl) was recently approved for treating patients with transfusion-dependent lower-risk myelodysplastic syndrome (MDS) with ring sideroblasts (RS) and/or SF3B1 mutation who were not eligible for erythropoiesis-stimulating agents (ESAs) or patients for whom those agents failed. Luspatercept acts as an activin receptor type IIB fusion protein ligand trap that targets the altered transforming growth factor beta pathway in MDS, which is associated with impaired terminal erythroid maturation. Treatment with luspatercept results in decreased SMAD signaling, which enables erythroid maturation by means of late-stage erythroblast differentiation and thus improves anemia. ESAs, the current standard first-line therapeutic option for anemic lower-risk patients with MDS, also improve red cell parameters mainly by expanding proliferation of early erythroid progenitor cells. However, erythropoietin (EPO) and its receptor (EPO-R) are also required for survival of late-stage definitive erythroid cells, and they play an essential role in promoting proliferation, survival, and appropriate timing of terminal maturation of primitive erythroid precursors. Thus, luspatercept joins the mechanism of ESAs in promoting erythroid maturation. Especially in the subgroup of MDS patients with RS, luspatercept showed high clinical activity for the treatment of anemia in the phase 2 (PACE-MDS) trial and subsequently in the phase 3 (MEDALIST) trial, which resulted in approval by both the US Food and Drug Administration and the European Medicines Agency in April 2020. Additional studies are needed to better understand the mechanism of action and pharmacodynamics of this novel agent in MDS.

Precision medicine in myeloid malignancies

Myeloid malignancies have always been at the forefront of an improved understanding of the molecular pathogenesis of cancer. In accordance, over the last years, basic research focusing on the aberrations underlying malignant transformation of myeloid cells has provided the basis for precision medicine approaches and subsequently has led to the development of powerful therapeutic strategies. In this review article, we will recapitulate what has happened since in the 1980s the use of all-trans retinoic acid (ATRA), as a first targeted cancer therapy, has changed one of the deadliest leukemia subtypes, acute promyelocytic leukemia (APL), into one that can be cured without classical chemotherapy today. Similarly, imatinib, the first molecularly designed cancer therapy, has revolutionized the management of chronic myeloid leukemia (CML). Thus, targeted treatment approaches have become the paradigm for myeloid malignancy, but many questions still remain unanswered, especially how identical mutations can be associated with different phenotypes. This might be linked to the impact of the cell of origin, gene-gene interactions, or the tumor microenvironment including the immune system. Continuous research in the field of myeloid neoplasia has started to unravel the molecular pathways that are not only crucial for initial treatment response, but also resistance of leukemia cells under therapy. Ongoing studies focusing on leukemia cell vulnerabilities do already point to novel (targetable) "Achilles heels" that can further improve myeloid cancer therapy.

Novel therapies in low- and high-risk myelodysplastic syndrome

Introduction: Myelodysplastic syndromes (MDS) comprise a heterogeneous group of myeloid neoplasms with diverse clinical courses. The revised version of the international prognostic scoring system (IPSS-R) provides risk stratification into 5 different groups. Areas covered: For lower-risk patients, red blood cell transfusions and iron chelation are the backbone of supportive care. In addition, erythropoiesis-stimulating agents (ESA) are used to ameliorate anemia. Lenalidomide is approved for the treatment of lower-risk patients with del(5q) who are transfusion-dependent. Patients with higher-risk disease should be offered allogeneic stem cell transplantation whenever possible. If they are unfit for transplantation or an appropriate donor cannot be found, hypomethylating agents may be used. Expert opinion: New therapeutic options for lower-risk patients include thrombopoietin analogues, the TGF-beta family ligand trapping drug Luspatercept, and the telomerase inhibitor Imetelstat. Combinations of hypomethylating agents (HMA) with other compounds, and inhibitors of bcl2, such as venetoclax are being developed for higher-risk patients. Finally, hypomethylating agents in combination with donor lymphocytes may lead to long-term remission following molecular or hematological relapse after allogeneic SCT.

Treatment of MDS

The heterogeneous nature of myelodysplastic syndromes (MDS) demands a complex and personalized variety of therapeutic approaches. Among them, allogeneic hematopoietic stem cell transplantation remains the only potentially curative option and is accessible to only a small number of fit patients. For the majority of patients with MDS, treatment strategies are nonintensive and risk-adapted (by the revised version of the International Prognostic Scoring System), ranging from iron chelation and growth factors to lenalidomide and hypomethylating agents. These approaches are noncurative and aimed instead at improving cytopenias and quality of life and delaying disease progression. These limitations underpin the need for more translational research-based clinical trials in well-defined subgroups of patients with MDS. Indeed, much progress has been made over the past decade in understanding the complex molecular mechanisms underlying MDS. Unfortunately, this has not yet translated into approval of novel treatment options. There is a particularly urgent medical need in patients failing current first-line therapies, such as with erythropoiesis-stimulating or hypomethylating agents. Nevertheless, actual developments are expected to pave the way for exciting novel therapeutic opportunities. This review provides an overview of the current therapeutic landscape in MDS focusing on recent advances in clinical and translational research.

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.

From cellular morphology to molecular and epigenetic anomalies of myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are a myeloid neoplasm with a propensity for natural evolution or transformation to acute leukemias (AL) over time. Mechanisms for MDS transformation to AL remain poorly understood but are related to genomic instability, which affects the production of the different cell lineages. Genomic instability is also generated by dysfunctional telomeres. Indeed telomeres, the protective ends of chromosomes are the backbone of genome stability. Nuclear telomere remodeling is an early indicator of nuclear remodeling preceding the onset of genomic instability and MDS. This review aims to revisit the pathogenesis and pathophysiology of MDS from morphology and cytogenetics to molecular and epigenetic mechanisms. Furthermore, this review will highlight and discuss recent breakthroughs in dysfunctional telomeres and nuclear telomere architecture roles in the pathogenesis and physiopathology of MDS in the global context of genomic instability.

Current treatment algorithm for the management of lower-risk MDS

Lower risk myelodysplastic syndromes (MDS), defined as MDS with a Revised International Prognostic Scoring System score ≤3.5 points, will remain a challenging entity in 2018. Supportive care continues to be the linchpin of treatment, although the options to reduce transfusion needs are broadening. To achieve red blood cell transfusion independence in non-del(5q) patients, erythropoiesis-stimulating agents remain a mainstay of therapy as long as endogenous erythropoietin levels are <500 U/L (and preferably <200 U/L). Experimental strategies for patients ineligible for erythropoiesis-stimulating agents or relapsing after gaining transfusion independence include immunosuppressive agents, transforming growth factor β inhibitors, and lenalidomide. All these alternatives have shown reasonable response rates in selected patient populations with lower risk MDS. Patients with del(5q) disease can derive long-term benefit from lenalidomide, and some patients remain transfusion free for extended periods even after discontinuation of the drug. In rare cases in which thrombocytopenia is the main clinical problem leading to clinically significant bleeding events, thrombopoietin receptor analogues may alleviate bleeding, increase platelet counts, and rarely lead to trilineage responses. It seems prudent to use these drugs only in patients with confirmed bone marrow blast counts <5%. Allogeneic stem cell transplantation is reasonable for patients with high molecular risk of progression and those failing several lines of treatment with signs of progression toward higher-risk MDS.

Progression in patients with low- and intermediate-1-risk del(5q) myelodysplastic syndromes is predicted by a limited subset of mutations

A high proportion of patients with lower-risk del(5q) myelodysplastic syndromes will respond to treatment with lenalidomide. The median duration of transfusion-independence is 2 years with some long-lasting responses, but almost 40% of patients progress to acute leukemia by 5 years after starting treatment. The mechanisms underlying disease progression other than the well-established finding of small TP53-mutated subclones at diagnosis remain unclear. We studied a longitudinal cohort of 35 low- and intermediate-1-risk del(5q) patients treated with lenalidomide (n=22) or not (n=13) by flow cytometric surveillance of hematopoietic stem and progenitor cell subsets, targeted sequencing of mutational patterns, and changes in the bone marrow microenvironment. All 13 patients with disease progression were identified by a limited number of mutations in TP53, RUNX1, and TET2, respectively, with PTPN11 and SF3B1 occurring in one patient each. TP53 mutations were found in seven of nine patients who developed acute leukemia, and were documented to be present in the earliest sample (n=1) and acquired during lenalidomide treatment (n=6). By contrast, analysis of the microenvironment, and of hematopoietic stem and progenitor cells by flow cytometry was of limited prognostic value. Based on our data, we advocate conducting a prospective study aimed at investigating, in a larger number of cases of del(5q) myelodysplastic syndromes, whether the detection of such mutations before and after lenalidomide treatment can guide clinical decision-making.

Association between Transfusion Status and Overall Survival in Patients with Myelodysplastic Syndromes: A Systematic Literature Review and Meta-Analysis

INTRODUCTION

Multiple studies show that transfusion independence (TI) in myelodysplastic syndrome (MDS) has a positive impact on overall survival (OS). To assess this, a systematic review and meta-analysis of the association between TI and OS in patients with MDS was conducted (PROSPERO ID: CRD42014007264).

METHODS

Comprehensive searches of 5 key bibliographic databases were conducted and supplemented with additional search techniques. Included were studies that had recruited adults aged >18 years with MDS and had examined the impact of transfusion status on OS.

RESULTS

Fifty-five studies (89 citations) were included. The vast majority reported a statistically significant hazard ratio (HR) for OS in favor of TI patients or in patients who acquired TI after treatment. A random-effects meta-analysis was conducted. Patients classed as TI at baseline showed a 59% decrease in the risk of death compared with transfusion-dependent (TD) patients [HR 0.41; 95% credible interval (CrI) 0.29-0.56], and this effect did not appear to interact significantly with illness severity (interaction coefficient HR 1.38; 95% CrI 0.62-3.41). A meta-analysis of studies where patients acquired TI was not possible, but those studies consistently reported a survival benefit for those who acquired TI.

CONCLUSION

The findings revealed a 59% pooled reduction in mortality among TI patients when compared with TD patients.

New insights into transfusion-related iron toxicity: Implications for the oncologist

Iron overload is a potentially life-threatening consequence of multiple red-blood-cell transfusions. Here, we review factors affecting excess iron distribution and its damage to specific tissues, as well as mechanisms of oncogenesis by iron. Although consequences of transfusional iron overload are best described in thalassemia major and related inherited anemias, they are increasingly recognized in acquired conditions, such as myelodysplastic syndromes (MDS). Iron overload in MDS not only impacts on certain tissues, but may affect the clonal evolution of MDS through generation of reactive oxygen species. Iron overload may also influence hematopoietic-stem-cell-transplantation outcomes. Novel MRI methods for assessing body iron have impacted significantly on outcome in inherited anemias by allowing monitoring of iron burden and iron chelation therapy. This approach is increasingly being used in MDS and stem-cell-transplant procedures. Knowledge gained from managing transfusional iron overload in inherited anemias may be translated to general oncology, with potential for improved patient outcomes.

Where Does Lenalidomide Fit in Non-del(5q) MDS?

Lenalidomide is nowadays an accepted standard treatment for del(5q) MDS. In non-del(5q) disease, its role is more difficult ot define. Studies have shown that about 18 % of patients treated with a standard dose of 10 mg/day on 21 out of 28 days might achieve erythroid transfusion independence rates that last 6 months or longer. The responses to lenalidomide seem to be inversely correlated to the pre-treatment EPO level. The higher the EPO level, the lower the responses. In the absence of other cytogenetic or molecular predictive factors that allow to discern which patient benefit most from treatment, its incorporation into the treatment algorithm is dependent on the available alternatives, including erythropoietic agents, immunosuppressive treatments and experimental strategies like thrombopoietin receptor agonists or the antagonists of transforming growth factor beta. Given that 90 % of responses to lenalidomide occur within four months of treatment, patients not responding within this time frame should discontinue therapy.

Myelodysplastic syndromes

Myelodysplastic syndromes are clonal marrow stem-cell disorders, characterised by ineffective haemopoiesis leading to blood cytopenias, and by progression to acute myeloid leukaemia in a third of patients. 15% of cases occur after chemotherapy or radiotherapy for a previous cancer; the syndromes are most common in elderly people. The pathophysiology involves cytogenetic changes with or without gene mutations and widespread gene hypermethylation at advanced stages. Clinical manifestations result from cytopenias (anaemia, infection, and bleeding). Diagnosis is based on examination of blood and bone marrow showing blood cytopenias and hypercellular marrow with dysplasia, with or without excess of blasts. Prognosis depends largely on the marrow blast percentage, number and extent of cytopenias, and cytogenetic abnormalities. Treatment of patients with lower-risk myelodysplastic syndromes, especially for anaemia, includes growth factors, lenalidomide, and transfusions. Treatment of higher-risk patients is with hypomethylating agents and, whenever possible, allogeneic stem-cell transplantation.

Long-Term Response in a Patient with del(5q) Myelodysplastic Syndrome Who Discontinued Lenalidomide and Obtained a Good Response and Tolerance to Rechallenge

Background

The introduction of the immunomodulatory drug lenalidomide has revolutionized the treatment of patients with myelodysplastic syndromes (MDS) and deletion of the long arm of chromosome 5. Treatment with lenalidomide results in transfusion independence in the majority of patients, but some questions remain unresolved, among them the duration of treatment. Moreover, a number of unexpected long-term remissions in patients who stopped lenalidomide for various reasons have been observed.

Case Report

We report the case of a 60-year-old Caucasian male with deletion of the long arm of chromosome 5 and International Prognostic Scoring System (IPSS)-defined low-risk MDS who was treated with lenalidomide, achieving complete cytogenetic remission and erythroid response. After tapering off and interrupting the treatment, the patient relapsed and showed a new response by lenalidomide retreatment. Six years after the initial treatment, we registered a durable erythroid long-term response and good tolerance, but there was no evidence of a very profound cytogenetic response compared to using lenalidomide as a first-line treatment. Cytogenetic and fluorescence in situ hybridization together with hemoglobin level, mean corpuscular volume (MCV) and vitamin B₁₂ level helped us to monitor the patient response; during the various phases of lenalidomide treatment, MCV and vitamin B₁₂ normalization correlated with good response.

Conclusion

Lenalidomide interruption and rechallenge in some 5q– MDS patients, with low risk according to the IPSS, is safe and feasible but does not result in a profound cytogenetic response.

Myelodysplastic syndromes with 5q deletion: pathophysiology and role of lenalidomide

Myelodysplastic syndrome (MDS) is a hematopoietic stem cell disorder primarily affecting CD34+ cells, characterized by ineffective hematopoiesis, often transforming into acute myelogenous leukemia (AML). A subset of patients has 5q deletion (del(5q)) as the culprit pathogenetic trigger. Del(5q) affects critical regions 5q31 and 5q33, leading to gene haplodeficiency with subsequent RPS14 haplodeficiency and P53 activation. Subsequent to P53 activation, erythroid cell apoptosis and ineffective erythropoiesis occur. Other pathogenetic elements include protein phosphatase 2a and CDC25C haplodeficiency and decreased miR-145 and miR-146a expression. Lenalidomide is an immunomodulatory agent that selectively suppresses the del(5q) clone. While the mechanism is not fully understood, it is associated with diverse molecular changes including stabilization of MDM2 with subsequent enhanced P53 degradation. Lenalidomide showed success in low- and intermediate-1-risk MDS as reported in the 002, 003, and 004 trials. However, in higher-risk MDS, the results of lenalidomide monotherapy were modest, mandating the use of combination therapy. The role and priority of lenalidomide varies between different guidelines, and accordingly, future efforts are necessary to reach a unified therapeutic algorithm. TP53 mutations are important predictors of AML progression and possible resistance to lenalidomide. It is recommended to identify TP53 mutation early in the disease since it may change the decision regarding choice of therapy. Challenges with lenalidomide therapy remain the long-term effects and timing of its discontinuation.

Lenalidomide for myelodysplastic syndromes with del(5q): how long should it last?

Lenalidomide induces in patients with myelodysplastic syndrome (MDS) and del(5q) erythroid and cytogenetic response rates as high as 75% and 50%, respectively. It is still unclear, however, how long lenalidomide treatment should be continued and whether or not the drug could be interrupted. To assess the feasibility of lenalidomide discontinuation, we revised a cohort of 16 low-risk MDS patients with del(5q) treated at our institute in a phase II multicentric Italian study. Among the 12 responding patients, four discontinued lenalidomide while in complete response. All four patients needed during treatment a permanent lenalidomide reduction from 10 to 5 mg/day because of haematological toxicity (three patients) or grade 3 muscular and bone pain (one patient). At lenalidomide discontinuation after 16, 20, 27 and 20 months from the start, respectively, all four patients were in complete hematologic response and three forth in complete cytogenetic response. Three patients are still in response after 36, 30 and 20 months from lenalidomide discontinuation, respectively: The remaining patient relapsed after 20 months, and she is now receiving a new course of lenalidomide. In conclusion, long-lasting remissions are achievable in MDS patients with del(5q) in complete response after lenalidomide discontinuation.

How we treat lower-risk myelodysplastic syndromes

Lower-risk myelodysplastic syndromes (MDSs) are defined as having low or intermediate 1 risk by the International Prognostic Scoring System and are characterized mainly by anemia in most cases. Supportive care--primarily red blood cell transfusions--remains an important component of their treatment, but exposes patients to insufficient correction of anemia, alloimmunization, and organ iron overload (for which the role of iron chelation remains debated). Treatment aimed at preventing anemia recurrence should therefore be used whenever possible. Erythropoiesis stimulating agents remain the first-line treatment of anemia in most lower-risk MDS without del(5q), whereas anemia of low-risk MDS with del 5q responds to lenalidomide in two-thirds of the cases, but this drug should be used cautiously because profound cytopenias may occur initially. Treatment after failure of those first-line therapies are disappointing overall, with many patients eventually requiring long-term transfusions, but encouraging results have been reported with hypomethylating agents and lenalidomide. Selected patients respond to antithymocyte globulins, and thrombopoietin receptor agonists are under investigation in lower-risk MDS with thrombocytopenia. Some patients, while remaining at a "lower risk" MDS level, have severe cytopenias and/or poor prognostic factors, found using newer prognostic parameters, or resistance to treatment, making them urgent candidates for more intensive approaches, including allogeneic stem cell transplantation.