HOW TO MANAGE... How to manage lower-risk myelodysplastic syndromes
Transcription
HOW TO MANAGE... How to manage lower-risk myelodysplastic syndromes
Leukemia (2012) 26, 390–394 & 2012 Macmillan Publishers Limited All rights reserved 0887-6924/12 www.nature.com/leu HOW TO MANAGE... How to manage lower-risk myelodysplastic syndromes MA Sekeres Leukemia Program, Department of Hematologic Oncology and Blood Disorders, Cleveland Clinic Taussig Cancer Institute, Cleveland, OH, USA Patients with lower-risk myelodysplastic syndromes (MDSs), usually defined as having an International Prognostic Scoring System score of 1.0 or less, and/or o5% myeloblasts, comprise the majority of newly diagnosed and established MDS patients and have a survival measured in years. Most will eventually require therapy for their disease, usually when MDS-related symptoms or transfusion requirements accelerate and outweigh potential drug-related toxicities. The decision of when to initiate therapy is far from straightforward. Erythropoiesis stimulating agents yield responses in up to 40% of appropriately selected patients, while disease-modifying drugs, including lenalidomide, azacitidine, decitabine and anti-thymocyte globulin, can evoke responses as high as 67% in patient subgroups. Newer therapies hold the promise of activity in patients who have failed standard regimens. Leukemia (2012) 26, 390–394; doi:10.1038/leu.2011.223; published online 9 September 2011 Keywords: MDS; therapy; outcomes Setting the stage for thinking about treating lower-risk MDS The myelodysplastic syndromes (MDSs) are a heterogeneous collection of clonal hematopoietic disorders defined by dysplasia of hematopoietic precursors and commonly associated with bone marrow hypercellularity, with resulting compromised hematopoiesis and peripheral blood cytopenias.1,2 As such, MDS really represents a collection of cancers, with the pathobiology of lower-risk subtypes characterized by a predominance of pro-apoptotic, pro-inflammatory cytokines and abnormalities in the bone marrow microenvironment, and higher-risk MDS typified by hypermethylation of tumor suppressor genes, activation of proliferative signals and a karyotypic profile similar to that seen in older patients with acute myeloid leukemia (AML).3–6 Clonal abnormalities have now been identified in 80% of MDS patients using complementary metaphase karyotyping and single-nucleotide polymorphism array technology.7 The age-adjusted incidence rate of MDS in the United States (US) is estimated to be 3.4 per 100 000 people.8 These data come from the Surveillance, Epidemiology and End Results program of the National Cancer Institute and the CDC (Centers for Disease Control and Prevention) and were collected from 2001 to 2003. While this would translate to B10 000 new cases per year, it is considered likely to be an underestimate, as the rate has increased over time, from 3.3 per 100 000 people in 2001 to 3.8 in 2004, in large part due to improved reporting practices within cancer registries.9 The US incidence rate is Correspondence: Dr MA Sekeres, Leukemia Program, Department of Hematologic Oncology and Blood Disorders, Cleveland Clinic Taussig Cancer Institute, Desk R35, 9500 Euclid Avenue, Cleveland, OH 44195, USA. E-mail: [email protected] Received 1 July 2011; accepted 6 July 2011; published online 9 September 2011 similar to that reported in western European countries such as England/Wales and Sweden (3.6 per 100 000), Germany (4.1 per 100 000) and France (3.2 per 100 000), but higher than is seen in Japan (1.0 per 100 000), where patients are diagnosed a median of 10–12 years younger than in western countries.10–13 Approximately 75% of newly diagnosed patients have lowerrisk disease (French-American-British categories of refractory anemia and refractory anemia with ring sideroblasts; World Health Organization categories of refractory anemia, refractory anemia with ring sideroblasts, refractory cytopenia with unilineage or multilineage dysplasia, MDS with deletion of chromosome 5q (del (5q)), and MDS unclassified; and IPSS (International Prognostic Scoring System) scores of low and intermediate-1), and patients in these subgroups have a predicted survival measured in years; the remaining 25% have higher-risk MDS (French-American-British categories of refractory anemia with excess blasts; World Health Organization categories of refractory anemia with excess blasts 1 and 2; and IPSS categories of intermediate-2 and high risk).14 With a median survival of o1.5 years, higher-risk MDS patients require immediate initiation of disease-modifying therapy, regardless of peripheral blood values. Patients with lower-risk disease often have the luxury of delaying treatment. Whether or not a heavily transfusion-dependent patient with IPSS lower-risk disease should truly be considered ‘lower-risk’ is a subject of debate, and would elevate a patient’s risk score in other prognostic classification schemes.15,16 How I decide when to start treating lower-risk MDS The first step in making this decision is to determine what the patient sitting in front of you knows about his or her diagnosis. Most initially have their MDS described to them as benignsounding conditions, such as a ‘bone marrow disorder’ (80%) or ‘anemia’ (56%). Only 6–7% have even been told they have a ‘cancer’ or ‘leukemia’.17 It is a challenge, then, to discuss therapies with substantial side effect profiles (when compared with the more common medications these septuagenarians and octogenarians are prescribed to control cholesterol and blood pressure) without first educating patients about the severity of their diagnosis. Most patients (55%) have no knowledge of their IPSS risk, and 42% do not know their bone marrow blast percentage. The next step is to determine the degree to which a patient’s symptoms are compromising his or her health-related quality of life. Lower-risk MDS patients report that, on average, their physical health is ‘not good’ almost 6 days out of every month, and that their disease limits their usual activities 4 days per month.17 No study has demonstrated an outcome benefit in early initiation of erythropoiesis stimulating agents (ESAs) or disease-modifying therapies. While hematopoietic stem cell transplantation is recognized as the only curative therapy for MDS, the survival advantage of this approach when compared Managing lower-risk MDS MA Sekeres 391 with other MDS therapies has been shown only in the context of a Markov decision analysis with narrow inclusion criteria, and even then specifically in higher-risk patients when offered as initial therapy.18 As patient reticence, comorbidities, lack of available donors and lack of insurance coverage will make this a viable option in o5% of patients,14 other treatments will be used the majority of the time, and can be considered essentially palliative. It stands to reason, then, that intervention is required only when a patient’s disease-related symptoms, or need for frequent transfusions, outweigh the anticipated side effects of a drug. Therapies I carry in my bag of tricks for treating lower-risk MDS ESAs are a good first step. A number of trials have been published using ESAs alone, at varying schedules and doses, or in combination with granulocyte colony stimulating factor or granulocyte macrophage colony stimulating factor, in MDS patients, with responses of B40% in lower-risk patients using IWG (International Working Group) criteria for response.19–29 Given the deleterious effect of ESAs on progression-free and overall survival in solid tumors (in at least eight studies), should they be avoided in MDS patients? No MDS patients were included in these worrisome trials, and three retrospective studies actually suggest a survival advantage for ESAs when compared with groups receiving best supportive care or diseasemodifying therapies, possibly through their effect on minimizing transfusion needs in patients (and thus significant volume shifts and the theoretical potential for iron overload), from Nordic, French and US analyses.30–32 All three studies attempted to control for selection biases by using inclusion criteria or multivariate analyses that adjusted for differences between patient groups in baseline characteristics. How do you determine which patients are most likely to benefit from ESAs? Two decision tools may be helpful. The first33,34 identified predictors of response to a combination of ESAs and granulocyte colony stimulating factor. It found that patients with low transfusion needs (o2 units packed red blood cell (pRBC) transfusions every 4 weeks) and a low baseline serum erythropoietin level (o500 IUFthe ‘good’ ESA predictive group) had a 74% chance of responding to ESAs, while those with high transfusion needs (X2 units pRBC every 4 weeks) and a high serum erythropoietin level (4500 IUFthe ‘poor’ ESA predictive group) had only a 7% chance of responding. Patients who had a mixed picture fell into an ‘intermediate’ ESA predictive group and had a 23% chance of responding to ESAs. A second decision tool incorporated individual patient data, including response rates, survival and quality of life, on 799 patients treated with either ESAs (394 patients) or diseasemodifying agents (405 patients) and applied these data to the Hellstrom-Lindberg model to determine the most appropriate up-front therapy for lower-risk patients.35 This treatment algorithm suggested that lower-risk MDS patients falling into a ‘good’ ESA predictive group should initially be treated with ESAs, while others (those falling into ‘intermediate’ or ‘poor’ ESA predictive groups) should probably be treated with diseasemodifying therapies initially. Recall that the response rate to ESAs in appropriately selected patients is 40%, and the median response duration is B2 yearsFmeaning that most patients will not respond to these growth factors, and those that do will lose their response eventually.30,36 For these patients, FDA (Food and Drug Administration)-approved options are limited. Probably, the best approach is lenalidomide, particularly in lower-risk patients with the del (5q) cytogenetic abnormality. Lenalidomide appears to function by selectively suppressing the del (5q) clone through inhibition of haplodeficient cell-cycle regulatory targets coded within the 5q31 commonly deleted region37,38 complemented by effects on the bone marrow microenvironment. The phase II registration study focused on patients with lowerrisk, transfusion-dependent MDS with the del(5q) abnormality (MDS-003).39 Lenalidomide was administered at a dose of 10 or 10 mg/day for 21 or 28 days of a 28-day cycle. Among 148 patients enrolled, 99 (67%) achieved transfusion independence, including every patient who experienced a cytogenetic response. The median duration of RBC transfusion independence was 2.2 years (range, 0.1–4.4 years). Subsequently, a phase III, double-blind trial of lenalidomide at two different doses vs supportive care in lower-risk, transfusion-dependent del(5q) MDS patients (MDS-004) demonstrated transfusion independence responses lasting 46 months in 43–52% of subjects, compared with 6% of controls. The cytogenetic response rate was 25–50% and the 3-year AML risk was 25%. Features predictive for transfusion independence response to lenalidomide include younger age, shorter duration of MDS, lower transfusion needs and treatment-related thrombocytopenia. Patients whose platelets declined by 50% or more within the initial 8 weeks of treatment were significantly more likely to achieve pRBC transfusion independence, compared with patients experiencing less severe myelosuppression.40 Treatment-related thrombocytopenia also correlated with cytogenetic responses, emphasizing the importance of successful suppression of the del (5q) clone with lenalidomide to achieve meaningful responses. Lenalidomide often is used off-label for the treatment of lower-risk, transfusion-dependent MDS patients who do not harbor the del (5q) lesion, based on a phase II study similar in design to the registration study.41 Of 215 patients enrolled, 56 (26%) achieved transfusion independence. Duration of response was less than for del (5q) patients, at a median of 41 weeks (range, 8–136 weeks). Grade 3 or 4 myelosuppression occurred in only 20–25% of patients, and unlike for del(5q) patients, was not associated with subsequent attainment of a transfusion independence response to therapy. Concern has been raised recently regarding the risk of secondary malignancies following lenalidomide exposure, particularly in populations of patients with multiple myeloma who have been treated with doses of lenalidomide that are higher than those used in MDS patients. On 8 April 2011, the US FDA announced its intention to review multiple myeloma clinical trial data to formally assess whether or not the risk of developing new types of cancers was higher in lenalidomide-treated patients, compared with those who did not take the drug. Whether these increased risks translate to MDS patients is unknown. A recent analysis of combined data from MDS-003 and MDS-004 of 286 del(5q) MDS patients treated with lenalidomide, with a median follow-up of B3 years, showed a rate of AML evolution of 17% at 2 years, while another analysis of 381 untreated del(5q) MDS patients, with a median follow-up of B4 years, showed a rate of AML evolution of 17% at 5 years.42,43 Okay, but what if my unfortunate patient does not have an isolated anemia? The therapies discussed so far target RBC deficiencies. If a lower-risk MDS patient presents with thrombocytopenia Leukemia Managing lower-risk MDS MA Sekeres 392 necessitating platelet transfusions, or resulting in bleeding episodes, options are even more limited. A phase I/II study in lower-risk MDS patients of romiplostim, a peptibody that increases platelet production through the thrombopoietin receptor (c-Mpl) and has been approved for use in patients with idiopathic thrombocytopenic purpura, has been completed.44 Of 44 patients enrolled into 1 of 4 dose cohorts to receive weekly injections of 300, 700, 1000 or 1500 mg romiplostim, 41 continued into the extension phase of the study with continued weekly injections, and 19 (46%) achieved durable platelet responses.45 Caution must be used in treating MDS patients with romiplostim, however, as two subjects progressed to AML during the study, and four others had transient increases in blast percentage. A randomized phase II study has just completed enrollment. Eltrombopag, another thrombopoietic growth factor, is being studied in higher-risk MDS patients. Particularly in lower-risk MDS patients with pancytopenia, two other approaches may be worthwhile. The first is antithymocyte globulin-based regimens, which capitalize on the theory that some lower-risk MDS subtypes may arise through T-cell mediated bone marrow destruction, similar to what occurs in aplastic anemia. These require an inpatient admission for monitoring of infusion-related adverse events; a steroid taper to ward off serum sickness; and are often coupled with other immunosuppressive agents, such as cyclosporine. Responses approach 30%, are higher in patients who are HLA DRB15 þ , younger, and have a shorter duration of transfusion dependence, and may be durable.46,47 Hypomethylating agents, such as azacitidine and decitabine, also can be used in lower-risk patients who fail other approaches or in whom ESAs would not be effective. Response rates are similar to off-label lenalidomide use, typical of historic responses to other disease-modifying drugs used in clinical trials in the lower-risk population.48 A patient’s cytopenias or quality of life must be severe enough, though, to warrant the adverse events associated with these drugs, which may be more severe to other lower-risk, disease-modifying approaches. On the topic of iron chelation To chelate or not to chelateythat is the question. A number of outstanding reviews on this topic have been written, and could easily consume the space of this entire review article.49–52 While consensus guidelines support chelation therapy for MDS patients with increased transfusion requirements (420–50 lifetime RBC transfusions) or with serum ferritin levels 42000 ng/ml, chelation therapy should be initiated with extreme caution, as it has never been shown prospectively to have an impact on end-organ function or on survival in MDS patients, and was approved by the US FDA based on limited data in MDS patients. Moreover, its use should be further limited to patients with lower-risk disease with a predicted prolonged survival, as higher-risk disease MDS patients are unlikely to live long enough to appreciate any benefits from chelation. Oral deferasirox and parenteral deferoxamine are the two ironchelating agents currently available in the US. Both medications appear have similar efficacy in depleting iron stores in patients with MDS.53 What I wish I had in my bag of tricks to treat lower-risk MDS The good news is help is on the way. The development plan for newer agents has incorporated the fact that most lower-risk Leukemia patients will have been treated for their disease with existing drugs, and thus are enrolling treated patients onto advanced stage clinical trials. Some of these drugs include ezatiostat, a glutathione analog prodrug GSTP-1 inhibitor that has yielded response rates (some bi- and tri-lineage) in up to 35% of lowerrisk patients in phase I and II studies;54 oral azacitidine, with a response rate of 53% among 15 MDS patients in a phase I trial;55 alemtuzumab, an anti-CD52 monoclonal antibody with a response rate of almost 80% in a study from the National Institutes of Health, albeit in a group of patients highly selected for factors such as HLA-DR15 status, age and months of transfusion dependency;56 and siltuximab, an anti-IL-6 monoclonal antibody.57 Conflict of interest The author declares no conflict of interest. References 1 Bennett JM, Catovsky D, Daniel MT, Flandrin G, Galton DA, Gralnick HR et al. Proposals for the classification of the myelodysplastic syndromes. Br J Haematol 1982; 51: 189–199. 2 Vardiman JW, Thiele J, Arber DA, Brunning RD, Borowitz MJ, Porwit A et al. 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