How i treat mpns.

How I treat MPNs.
Commentary on the season's scientif ic f indings and MPN events.
In this concluding section of diagnosis and treatment of MPNs, four of the world’s pre-eminent MPN researchers
and clinical specialists combine current thinking from Europe and the United States. Dr. Claire Harrison, Dr. Hans
Hasselbalch, Dr. Richard Silver and Dr. Ruben Mesa share their approach to treating the Philadelphia negative
myeloproliferative neoplasms, essential thrombocythemia, polycythemia vera and myelofibrosis.
Dr. Claire Harrison: How I treat essential thrombocythemia.
Consultant haematologist and Deputy Director, Guy’s and St. Thomas’ NHS.
We will review any patient with a platelet count over 450. All will have a clinical evaluation and directed investigationwhich will always include at least a blood film, inflammatory markers, iron status, JAK exon 14 and MPL exon 10mutation screen. I almost always do a BMBx with cytogenetics which is reviewed by me along with all the diagnosticinformation. Even if a patient comes for a second opinion I am likely to request to see all the diagnostic material.
Then I discuss findings and options with the patient.
We discuss the natural history of essential thrombocythaemia with short and medium terms risks of clotting (thrombosis)and bleeding (haemorrhage) events and long term risks of transformation to myelofibrosis (with stiffened bone marrow,enlarging spleen, falling blood counts and aggressive disease course) or acute leukaemia. In particular we discuss thatmany patients do not suffer any of these complications. This condition is due to abnormal control of blood cellproduction. In about half of patients this is due to an abnormal sequence in a gene called JAK2; this change causesincreased growth and is known as JAK2 V617F. There is no clear difference in the disease of patients who either haveor do not have this mutation.
We reviewtreatment strategies for this condition ranging from management of cardiovascular risk factors (control of bloodpressure screening for cholesterol problems) and low dose aspirin for patients without increased risk of bleeding.
Control of the platelet count with a drug is offered for high risk patients, high risk implying that patients are at high risk ofparticularly clotting but also bleeding events. Such patients being defined by any ONE of: Age over 60 years, previousclotting or bleeding events or platelet count more than 1500×109/l. Under some circumstances — treated hypertension ordiabetes — there is also emerging evidence for an elevated white cell count as a marker of high risk disease.
The three main treatment options and their various side effects are explained in depth as summarised below.
Hydroxycarbamide or Hydroxyurea being the “gold standard” therapy supported by trial data showing it reduced clotting(especially in JAK2 V617F positive patients) and bleeding events and potentially slow transformation to myelofibrosisand being associated with few short term side effects – mild stomach upset, some mouth and skin ulceration but carriesthe potential un- quantified risk of slightly increasing transformation to leukaemia. In comparison Anagrelide does reduceclotting and bleeding but less well than Hydroxycarbamide, it does not slow myelofibrotic transformation but also doesnot increase the risk of leukaemia. The major side effects of Anagrelide being: headaches, palpitations, diarrhoea, fluidretention. Lastly Interferon given by injection has never been compared formally to the other two treatments but is likelyto be similar with some anecdotal reports suggesting reduction or reversal of fibrosis, safety in pregnancy and no risk ofleukaemia. The side effects of Interferon being: flu- like symptoms for the first two weeks, and high incidence of fatigueand depression in the long term.
I encourage all patients to have an annual review of weight, blood pressure, cholesterol and diabetes screen. All areencouraged and advised on healthy lifestyle not smoking etc. I tell all patients that this is a form of blood cancerexplaining that there is a spectrum of cancers. Then Low risk ET, age less than 40, platelets less than 1500 (sometimes I allow this to be higher) no risk factors (see paras
above) get aspirin alone, Sometimes I do not use aspirin if the patient has a bleeding phenotype or I will stop it if the
patient bleeds ++ on aspirin. The results from low risk arm of the PT- 1 ( Primary Thrombocythaemia 1) trial will be
important here to be able to say more definitively what the natural history is. This data is due in 2014.
Int ermediat e risk ET, age 40- 60 platelets less than 1500, no risk factors. Thereis little evidence for clinical practice
here. We are awaiting results of the intermediate risk arm of PT- 1). I explain this to the patient and offer
aspirin alone. I would offer more to patients with strong family history of vascular event etc.
High risk ET. In addition to health advice I explain all 3 options and offer the patient a choice, supported by written
information. In general I would usually use HU or IFN up front reserving anagrelide for second line where I often prescribe
it in combination with HU.
All patients receive written information about their disease and different treatment options. They are also giveninformation about patient support groups (we hold one at least twice a year on behalf of MPD Voice. All patients are encouraged to bring a friend or relative to the consultations initially.
All patients at diagnosis also see a specialist nurse. All patients receiving treatment beyond aspirin have a structuredconsent and detailed instruction/review of potential side effects, after starting they get a follow up call within a week fromthe nurse. All have full access to contacts within the department. We also offer full health psychology support if needed.
Follow ups: We offer a range including telephone and face to face. All patients have an annual review including film andspleen examination, skin exam for HU patients, thyroid and liver and depression screen for IFN every 6 months. Mostpatients on cytoreductive drugs once stable are reviewed every 3- 4 months, low and intermediate patients between 4-6- 12 monthly depending on disease duration, stability and patient preference.
We offer repeat BMB if indicated, we encourage it for patients on anagrelide every 3- 4 years and for young patients. Allpatients are offered the opportunity to take part in our national sample banking for MPN which involves a blood sampleand mouthwash (formally known as buccal sample).
I also discuss the risks of inheritance of this condition with regard to their children. There is a slight increase in risk thatfirst degree relatives of patients with these conditions will develop the same condition. The magnitude of risk however isvery low with an overall risk of approximately 1 in 20,000. I would not recommend routine screening of children unlessthey are due to undergo a high risk procedure or have suggestive symptoms If appropriate, with regard to pregnancy I discuss the following: The combined oral contraceptive pill is not an appropriate means of contraception because of the added risk ofthrombosis. In terms of pregnancy itself I would imagine that the pregnancy could be managed jointly between localhaematologists and obstetricians and that once pregnancy occurs we would send a copy of our latest pregnancyprotocol to guide management if that was desired. I would anticipate that pregnancy is likely to be both successful anduncomplicated. However, there is an increased risk of 1st trimester miscarriage possibly between 1:6 and 1:8pregnancies and of events later in pregnancy such as a growth restricted baby due to blood clotting in the placenta orrarely a late pregnancy foetal death for the same reason. Approximately 70- 75% of pregnancies in patients with thiscondition are successful. During pregnancy low dose aspirin should be given and uterine artery Doppler’s determined atthe 20 weeks scan repeated at 24 weeks if notching is present. If notching persists then consideration should be given toincreased therapy (e.g. adding or increasing the dose of low molecular weight heparin or IFN) and the pregnancymonitored more closely.
In terms of maternal risk this generally occurs in the post partum period, in particular the first six weeks after the baby isborn, and relates to an increased risk of clotting. For this reason we would recommend in addition to Aspirin throughoutpregnancy six weeks of low molecular weight heparin in the post partum period.
This is an exciting and interesting time for all patients with MPNs. For our patients wit ET we need some improvements inrisk stratification to better understand the long term effects of many treatments and to safely introduce some of the ecitingnew therapies for this disease area.
Dr. Hans Carl Hasselbalch: How I treat ET, PV, and MF with interferon.
Department of Hematology, Roskilde Hospital, University of Copenhagen
Int roduct ion
Most guidelines and recommendations for the “Goals of Therapy in ET and PV ” during the years have aimed atreducing the risk of thrombosis and hemorrhage without increasing the inherent risk of leukemic and myelofibrotictransformation by treating patients with potentially leukemogenic agents according to the concept “Do no Harm to ThePatient.” In recent years additional major issues have also been addressed , including quality of life (QoL) of patientswith ET and PV.
Several QoL studies in ET and PV have convincingly shown that even in the early MPN stages a subset of patients isheavily disease burdened . Another important issue is the revival and renaissance of interferon- alpha2 (IFN) , beingused for decades in the treatment of ET and PV . Recently, IFN has been shown to be able to induce major molecularremissions as assessed by the JAK2V617F allele burden, reducing the risk of thrombosis and hemorrhage and in asubset of patients even reverting disease progression with normaliz ation of bone marrow architecture . This “minimalresidual disease “ condition may even be sustained after discontinuation of IFN for several years .
Accordingly, IFN has the potential to modify disease progression in a subset of patients – indeed supportive of theconcept of intervention with IFN at the earliest disease stage , when a favourable outcome is likely the very best.
Importantly, they also urgently call for new Standards for therapeutic goals in ET and PV.
When addressing the goals of therapy in ET and PV it is important also to address the burden of ET- and PV- relatedcomorbidities , which actually may heavily influence the QoL of our ET and PV patients. All these comorbidities – egcardiovascular, pulmonary, renal, skeletal , inflammatory and autoimmune – should be diagnosed and treated at thevery early stage of the disease upfront at the time of diagnosis .
Cure is the optimal goal of treatment of any cancer and if not possible then to convert to a stage of “minimal residualdisease.” A prerequisite for achieving these goals is that the cancer is diagnosed at the earliest stage of itsdevelopment , when the tumor burden is the least at any time and accordingly the chance of a favourable outcome thebest. In the context that ET and PV are early stages of myeloid cancers, which untreated may steadily progress to theadvanced myelofibrosis stage with myeloid metaplasia comparable to an untreated disseminated cancer , it seemsrational to start treatment with IFN at the time of diagnosis. The goal is to minimiz e and control the disease at the earlycancer stage and hopefully inhibit cancer progression.
In the perspective that the MPNs – ET, PV and PMF – are cancers at different stages in the biological continuum fromearly cancer stage (ET) to the advanced myelofibrosis stage. This last is characteriz ed with metastasis ( = egress ofCD34+ cells from the bone marrow to seed at extramedullary sites like the spleen and liver ). In the following I will arguefor the rationale of early intervention with interferon in these cancers instead of a “wait and watch” strategy.
The Wait and Wat ch St rat egy
The goals of therapy in ET and PV are ultimately to improve QoL by reducing the risk of thrombosis and hemorrhage,relieve symptoms and prohibit disease progression towards myelofibrosis and leukemic transformation. The pathway tofollow to obtain these goals may differ being dependent upon access to IFN or not. In countries/centres not havingaccess to treat with IFN a large number of patients are followed without cytoreductive therapy according to a risk-adapted treatment approach being founded on the rationale that we shall “Do no Harm “ to our patients., Previous cytoreductive therapies ( busulphan, pipoproman, p 32 ) were associated with a definite increase in the risk ofdeveloping acute myelogenous leukemia (AML). The same concern exists in regard to hydroxyurea (HU) which is thecytoreductive agent being used worldwide to treat patients with ET and PV. Accordingly, at most “non- IFN” centres – ETand PV patients are not considered for cytoreductive therapy, unless categoriz ed as “high risk “ ( prior thrombosis .> 60years, platelet counts > 1500 Mia/L).
Importantly, this risk- adapted therapy does not capture the current symptomatic disease burden in the individual patient– the need of the patient – but is highly dictated and influenced by the concern of HU as a leukemogenic agent .
Younger low- risk ET and PV patients (<60 years of age) are left untreated until a major thrombotic event occurs,classifying the patients as high risk and then qualifying for cytoreductive therapy, which in most centres is HU.
Unfortunately, however, this agent may be associated with significant skin toxicity , skin cancer, myelodysplasia (MDS)and/or AML after long- term treatment (>10 years) in a subset of patients. Importantly, short term treatment with HU ( lessthan 5- 10 years ) does not seem to carry an increased risk of MDS or AML . At several centres in Europe and US IFNinstead of HU is used routinely for younger patients.
The Early Intervention Concept in The Interferon Era For decades we have known that IFN is able to induce hematological remissions in patients with ET and PV. In recentyears several studies have shown that treatment with IFN is also accompanied by “complete” or major molecularremissions ( as assessed by a decline in the JAK2V617F allele burden) in patients with ET and PV. These molecularremissions are associated with normaliz ation of the bone marrow and are sustained after discontinuation of IFN (minimal residual disease/operational cure) in a subset of patients. Taking into account that ET and PV are early cancerstages which – left untreated – may progress to myelofibrosis and AML it seems logical to consider early upfrontintervention with IFN in order to prohibit clonal evolution Despite the huge number of studies displaying excellent response rates on IFNtreatment with IFN is still consideredexperimental therapy in many MPN- centres of excellence today. The arguments against IFN are many, including (1)alack of controlled studies to justify the risk of unknown long- term health effects associated with nonconventionaltherapeutic approaches , (2) the need to reserve IFN- alpha2 for selected categories of patients due to high cost andtoxicity, or (3) those who are resistant or intolerant to HU. Finally, there is concern (4) that its use may be governed bylocal experience with IFN. Thus, several expert reviews and recommendations addressing the issue “how to treat ETand PV ” have been less likely to credit the beneficial effects of IFN in these patients .
The MPNs are clonal myeloid neoplasias , in which the JAK2V617 mutation is detectable in virtually all PV patients andin about half those with ET and PMF. These diseases may be considered as a biological continuum from early cancerstage (ET) to the advanced myelofibrotic burnt- out phase. The prognosis of patients in the earliest cancer stage – theET- population – has been variably reported , five- and 10- year survivals being reported significantly reduced in onestudy ( about 75 % and 60 %, respectively and accordingly significantly reduced mainly attributed to myelofibrotic orleukemic transformation ). Other studies have demonstrated better survival curves and today it is generally held that lifeexpectancy of the ET- population does not differ significantly from the general population. However, the QoL even in ETpatients may be severely impaired due to a high morbidity rate elicited by thrombohaemorrhagic complications ormicrovascular occlusive symptoms.
The prevalence of myelofibrotic transformation in ET has been variably reported. Most studies suggest the risk ofmyelofibrotic transformation increases with disease duration. On average the probability of myelofibrosis is 5 % after 5years, 10 % after 10 years , 15 % after 15 years and 20 % after 20 years and the median interval from ET diagnosis todevelopment of overt myelofibrosis about 8 years .With the 2008 WHO classification, the ET- population has beensubdivided into 2 distinct entities – true ET and early prefibrotic myelofibrosis (epMF)), the latter disease entity having aninferior survival as compared to genuine ET.
The impact of reticulin grade at diagnosis has recently been addressed in the ET- population (the PT- 1 ET –trial) ,showing that the reticulin grade represents an independent prognostic marker. Furthermore, reticulin grade has beenshown to correlate positively with white blood cell and platelet counts. Finally , in the same study elevated reticulin levelsat presentation predicted higher rates of arterial thrombosis, major hemorrhage , and myelofibrotic transformationindependently of known risk factors .
Leukemic transformation in ET has been shown to increase with disease duration , with an incidence of 1- 2.5% in the firstdecade after diagnosis, 5- 8% in the second decade and thereafter continuously rising . A most recent multicenter studyof 1.104 “ET” patients with the aim of investigating the clinical relevance to distinguish between “true” ET and “false” ET(= epMF) dissected the” ET- population” into these 2 subgroups – “false” ET (epMF) and “true ET”, the latter categoryhaving a better survival than the “false” ET- population .Importantly, however, the 5- year cumulative incidence ofthrombosis in “true” ET compared to epMF was 8.7 % and 6.6 %, respectively, the 10- year cumulative incidence ofthrombosis in “true” ET compared to epMF was 16.2 % and 17.9 %, respectively and the 15- year cumulative incidenceof thrombosis in “true” ET compared to epMF was 21.5 % and 25.4 %, respectively.
Accordingly, the incidences of thrombotic complications were similar between the two groups. Of note, the 15- yearmyelofibrosis transformation rate in “true” ET compared to epMF was 9.3 % and 16.9 %,respectively. Anemia and ahigher leukocyte count (> 11 MIA/L) were risk factors for inferior survival . Also, in epMF patients a higher leukocyte counthas been reported to correlate with an increased risk for total thrombosis and in particular, with an increased risk forarterial thrombosis and a lower hemoglobin level was associated with an increased risk for venous thrombosis .
For all the above reasons it is timely to rethink and reconsider if it is still, in 2013, appropriate to base decision- makingon when to treat ET patients on risk stratification systems which are based upon age (< 60 years) and the acquisition ofa potentially life- thrombotic event which then qualify for cytotoxic treatment. Importantly, induction of “complete”hematological /major molecular remissions during IFN treatment may be associated with a decline in the occurrence ofthrombotic and hemorrhagic complications . This latter observation has not yet been demonstrated in a prospectiverandomiz ed study , but hopefully the MPN- Consortium Study may yield useful information on this topic.
The morbidity of patients with epMF is partly explained by an increased risk of arterial thrombosis but also progressionto overt myelofibrosis with huge splenomegaly and ultimately leukemic transformation. The increased risk of thrombosismay be explained by the leukocytosis , which accompanies most patients with epMF since leukocytosis per se is athrombogen factor in MPNs – akin to the general population . Supporting the viewpoint that both platelet and leukocytecounts should be normaliz ed in ET are the findings in a most recent study that a platelet count outside of the normalrange during follow- up was associated with an immediate risk of major hemorrhage, but not thrombosis and an elevatedleukocyte count during follow- up was associated with thrombosis and major hemorrhage .The authors (Need a citationhere) concluded that the aim of cytoreduction in ET should be to keep the platelet count, and arguably also theleukocyte count within the normal range. Since IFN may normaliz e elevated leukocyte and platelet counts , induce adefinite decline in the tumor burden at the molecular level ( JAK2V617F) and – in addition – has the potential to revertbone marrow reticulin and reduce enlarged spleens in MPNs – it seems rational and timely to treat with IFN instead ofHU or anagrelide .
JAK2V617F: positive ET or indolent incipient PV ? A controversial issue in the JAK2V617- positive ET- population concerns the fact that a considerable proportion ofJAK2V617F positive ET patients ( up to about 60 % ?) indeed has PV as assessed by the historical “golden standard”for a diagnosis of PV – an increased red cell mass (RCM) and an increased plasma volume . This has most recentlybeen emphaz ised and recogniz ed but irrespective of the overt misclassification of a high proportion of PV patients asET without measurement of RCM this investigation is not performed in several MPN- centres of excellence. By ignoringthe impact of such a misclassification, the clinical phenotype, the rate of thrombohemorragic complications, theprognosis in regard to clinical, biochemical and histopathological findings and comorbidities and the associations to theJAK2V617F allele burden in the “ET- population” have been erroneously described in several studies. This occurs whenthe ET population is mixed with patients in a more advanced disease stage (PV) within the biological continuum from ETover PV to myelofibrosis.
Therefore, RCM estimation should ideally be performed in all “JAK2- positive ET patients” at the time of diagnosis inorder to identify the PV patients amongst JAK2V617F- positive ET patients, patients who otherwise would not be treatedwith phlebotomies and accordingly be at risk of thrombosis due to the expanded RCM .
Chronic inflammation as the driving force of clonal evolution In the perspective, that chronic inflammation may be an important contributing factor in MPN pathogenesis, it seemsrational to interrupt clonal evolution at the earliest disease stage – ET – thereby aiming at reducing or eliminating allpotential factors which might contribute to morbidity and mortality. In the ET- population these factors include elevatedleukocyte and platelet counts but – in addition – circulating leukocyte- platelet aggregates elicited by in vivo leukocyteand platelet activation and being sustained and perpetuated by inflammatory products released from the malignantclone Furthermore, in the context of chronic inflammation as a potential promoter of cancer development and progression andgiven that ET and PV patients indeed have an increased risk of second cancer – both hematological and non-hematological — it is also for these reasons important to alleviate the chronic inflammatory drive. Chronic inflammationand a deregulated immune system with impaired tumor immune surveillance may be important factors in thepathogenesis and progression of MPNs . Accordingly, a rational therapeutic approach may include immune- enhancing treatment with IFN at the time of diagnosis when the tumor burden is the least and consequently the outcome of IFN likelythe very best.
In the context that data generated from a large number of studies during the last 25 years convincingly have shown IFNto normaliz e elevated leukocyte and platelet counts in concert with a decrease in spleen siz e and a reduction in theJAK2V617- allele burden – thereby alleviating all conventional factors of disease burden ( leukocyte count, plateletcount, spleen siz e and JAK2V617F mutational load ) and of significance for thrombosis and bleeding – early interventionwith IFN may likely also prohibit clonal expansion and myelofibrotic and leukemic transformation .
How to treat with IFN- alpha2 in myelofibrosis ? Essential thrombocythemia and PV may progress to post- ET myelofibrosis or post- PV myelofibrosis , the risks beingthe highest in “ET” patients with epMF and in PV- patients with an increased amount of bone marrow reticulin at the timeof diagnosis . About 50 % of patients with primary myelofibrosis (PMF) harbor the JAK2V617F- mutation, the largemajority being homoz ygous, reflecting the heavy “ tumor burden” in advanced myelofibrosis with massivesplenomegaly. Indeed, most likely all patients with newly diagnosed JAK2V617F- positive PMF have had undiagnosedMPN- disease for decades with disease evolution from early stage ( JAK2V617F- positive ET ) over PV to myelofibrosis .
During the last 30 years several studies have convincingly and repeatedly shown that even patients with myelofibrosisand large spleens may benefit from IFN- alpha2 by a reduction in elevated leukocyte and platelet counts in concert withresolution of huge splenomegaly and alleviation of hypermetabolic symptoms, bone pain and even improvement inanemia. Most recently, these early observations have been substantiated by several important papers showing thatpatients with hypercellular myelofibrosis may actually greatly benefit from IFN- alpha2 being able to normaliz e elevatedblood cell counts in concert with a reduction of spleen siz e and – importantly – regression of bone marrow fibrosis.
Treatment with IFN- alpha2 in myelofibrosis may be associated with more side effects than when treating ET and PV-patients. Although the most recent series conclude that IFN- alpha2 was well tolerated in the large majority it is a clinicalexperience that “inflammation symptoms” (fatigue, fever , weight loss , muscle and joint pains) may temporarily increaseduring the first months of therapy. Actually , these symptoms may reflect the outcome of immune cells attacking the huge“tumor burden.” Very often , combining IFN.- alpha2 with prednisolone ( 50 mg per day in 2 weeks and afterwards duringthe following weeks gradual dose reduction to about 10 mg /day ) may promptly alleviate the symptoms . In addition – arise in Hb- concentration is usually seen . The dosage of IFN- alpha2 is as given above for ET and PV- patients withsupplementary paracetamol according to the same schedule Conclusions
ET , PV and myelofibrosis are clonal myeloid neoplasias in a continuum from early disease stage to advanced burnt-out myelofibrosis , reflecting increasing genomic instability and complexity with a steady accumulation of mutations ofimportance for disease progression . One single agent – IFN – has been shown to induce complete hematological anddeep molecular remissions in a large proportion of ET and PV patients with reversal of disease progression, beingsustained off therapy for several years in a subset of PV patients.
IFN is able to revert abnormal bone marrow architecture with regression of bone marrow reticulin fibrosis, even inpatients with hypercellular myelofibrosis . An increase in bone marrow reticulin in ET implies an inferior response to IFN (assessed by fewer patients with complete hematological remissions after about 1 year compared with those patientswithout excessive bone marrow reticulin) and an increased risk of thrombosis and myelofibrotic transformation.
IFN- alpha2 treatment of ET and PV is associated with a decrease in the frequency of thrombosis and bleeding – themajor determinants of symptomatic disease burden in MPNs – and a decrease in reticulin fibrosis. Initial bone marrowreticulin fibrosis in ET and PV exerts an impact on clinical outcome with a propensity to develop post- ET and post- PVmyelofibrosis .
Leukocytosis is a risk factor for thrombosis, associated with vascular complications and an inferior survival in ET and PVas in the general population . And, finally, treatment with IFN in the early disease stage may be associated with a bettertreatment response, likely explained by a lower JAK2V617 mutation load and the absence of additional mutations. Allthese observations are supportive and argue for early intervention with IFN in ET and PV, the goal being to normaliz eelevated thrombogenic cell counts and block the otherwise predictable path towards myelofibrotic and leukemictransformation .
Dr. Richard Silver: How I treat PV with interferon.
Professor of Medicine and Director of the Leukemia and Myleoproliferative Center at New York Presbyterian-Weill
Cornell Medical Center.
Focus on recombinant interferon- alpha2b (rIFN- α2b, Intron® ) induces complete hematologic remissions in patients withmyeloproliferative neoplasms (MPNs) but its use has been limited by side effects owing to relatively high doses used.
Now, low dose rIFN- α is stressed, starting relatively early in the course of the MPNs. In polycythemia vera (PV) this hasresulted in significant clinical, hematological, morphologic and molecular response manifested by reduction in theJAK2V617F allele burden, sustained even after discontinuation of rIFN. In essential thrombocythemia (ET), platelet countreduction is prompt and durable without treatment. In hypercellular primary myelofibrosis (PM), rIFN- α has restorednormal blood counts, reduced splenomegaly and induced morphologic marrow remissions.
rIFN- α2b Intron® was most commonly used in clinical practice prior to the introduction of the PEG- rIFNs. The pegylatedforms of rIFN are universally used in Europe, but not in the USA where insurance issues frequently affect selection oftreatment. It has been suggested that rIFN- α2b may be associated with more side effects than the pegylated formsbecause of its shorter half- life, resulting in fluctuating blood levels.The efficacy, safety and toxicity profiles of rIFN- α2band PEG- rIFN- α2 have not been compared in patients with MPNs. However, such a trial has most recently beenlaunched in Denmark.It has recently been suggested that differences observed may be a matter of dose.
Treatment of Polycythemia Vera with Interferon The clinical effectiveness of rIFN- α2b was demonstrated nearly a quarter of a century ago in PV in the United States andalmost simultaneously in ET patients by French and Austrian groups. Approximately 400 patients with PV have beenincluded in nearly 20 trials using different preparations of rIFNs, usually with small numbers of patients, the largestconsisting of 55 patients. Reduction in PHL [phlebotomy] rates have ranged from 47 to 100% in 12 of 17 trials, withcomplete response in 5, depending upon the dose and tolerance of the patient. Discontinuation rates have ranged from14% to 40% depending upon the dose. It is impossible to state whether one form of rIFN- α2 is superior to another withrespect to clinical results, but recent reviews would suggest differences are quantitative rather than qualitative.
Heterogeneous response criteria have been used to evaluate efficacy including those of the PVSG and the EuropeanLeukemiaNet (ELN). Agreeing on standard criteria for use in MPNs will help avoid conflicts in interpretation of results inthe future. However, these studies have convincingly shown that rIFN- α2 relieves pruritus, rapidly normaliz es elevatedwhite blood and platelet counts in the large majority of patients, and is accompanied by a reduction or elimination of theneed for PHLs. With longer treatment (> 6- 12 months), splenomegaly is reduced or eliminated and in some casesmarrow can be normaliz edand regression of fibrosis, if present, can occur. We have found treating marrow fibrosis in PVmore satisfactory and facile than in PM. It is of considerable interest that in our patients treated with rIFN- α2, thrombosis-free survival has been remarkably good, perhaps explained by both the cytoreductive effect of rIFN- α2 per se and/orour meticulous attention to target hematocrit levels.
Although rIFN- α2 will predicatively lower the white blood cell count and platelet count rapidly (1- 4 weeks) after initiationof treatment, it will not substantially reduce the RBC count for which PHL is required. Accordingly, we advocate an initiallyvigorous PHL program as an adjunct to rIFN therapy to reduce whole blood viscosity which together with leukocytosisand thrombocytosis plays a role in the pathogenesis of thrombosis. Our Italian other colleagues have recently confirmedthe importance of a hematocrit less than 45% in men (and we require less than 42% in women).
These data initially implied that overall survival for patients treated with PHL- O was superior to those treated with either32P or chlorambucil based on the old Polycythemia Vera Study Group analysis. Consistently overlooked was the factthat the large majority of patients in the PHL- O arm were rapidly removed from study following an unacceptably high rateof thrombosis during the first 5 years, and were thereafter treated with other drugs, including hydroxyurea, and 32P.
Unfortunately, these patients were not followed systematically but allegedly had the lowest morbidity rate and the bestsurvival. The number of patients who could be treated throughout with PHL- O were few indeed based upon a Frenchstudy. Moreover, abundant data exist that chronic iron deficiency state which results after repeated PHLs is associatedwith a wide variety of impairments ranging from Plummer- Vinson syndrome to decreased cognitive function, cardiacimpairment and stroke. The use of rIFN- α2 in PV corrects even the worst hypochromic/microcytic indices by suppressingerythroid activity in the marrow.
We believe* that all alkylating agents should preferentially be avoided due to their leukemogenic potential, clearly
evidenced in several prospective trials including one recently of pipobroman, still used in several European countriesbut not in the US. With respect to long- term treatment with hydroxyurea and the risk of developing myelodysplasticsyndrome and/or acute myelogeneous leukemia: there has been no randomiz ed control trial (RCT) demonstrating anincreased leukemogenic potential of hydroxyurea. Of note, these secondary malignancies occur many years afterexposure, and in our opinion, only prospective trials with a median follow- up longer than 10 years can accuratelyestimate the true leukemic risk. The only control with a follow- up of this duration compared hydroxyurea with pipobromanin PV, and clearly showed that pipobroman is leukemogenic. However, the cumulative incidence of leukemic events inthe hydroxyurea arm was 16.5% and 24.2%, after 15 and 20 years follow- up, respectively. Such numbers couldconceivably reflect the rate of transformation of an MPN in the very long term, and not necessarily be indicative of theeffect of a cytotoxic agent such as hydroxyurea. Of great clinical importance, there is no evidence that rIFNs areteratogenic or leukemogenic.
* Dr. Silver is referring to work he has done with Dr. J.J. Kiladjian and Dr. H.C. Hasselbalch, Dr. Ruben Mesa: How I treat myelofibrosis.
Ruben A. Mesa, M.D. Professor and Chair Division of Hematology and Medical Oncology, Deputy Director, Mayo
Clinic Cancer Center.
Let me begin by saying it is a great pleasure to have been invited by Zhenya Senyak to be able to contribute to this
edition of MPN Forum Quarterly Journal. I think the first comment I would make in terms of “how I t reat myelof ibrosis”
is to recogniz e that patients with myelofibrosis are a very heterogeneous group of individuals. Having seen over a
thousand people with this disease over the years, people can range from being in their 30s, typically at the very
youngest end, to being in their 80s, 90s, and really no upper cut- off in terms of age limit. People can range from having
disease that severely affects them from the moment they are diagnosed to having an accidental finding of a mildly
enlarged spleen at the time of a general physical. People can range from a disease that clearly is life threatening to
them to a disease that will not necessarily impact their lives to a great degree. So, with all of these caveats, I would say:
Make sure I have an accurate diagnosis of myelofibrosis.
Having an accurate diagnosis of myelofibrosis is essential to make sure that: 1. It truly is a bone marrow disease.
2. It is not another bone marrow disease in which we also see scarring in the bone marrow, such as myelodysplastic syndrome with fibrosis, chronic myeloid leukemia with fibrosis, or the uncommon but still possible secondarycause of myelofibrosis, whether it be autoimmune disease or other marrow trauma. I would refer you to the MPNForum sessions discussing Once the diagnosis is established, there are three groups of individuals with myelofibrosis, those with primarymyelofibrosis, those in which we find the disease as the first diagnosis, or those that clearly had a pre- existingpolycythemia vera or an essential thrombocythemia and have subsequently progressed to myelofibrosis. Although thereare three groups of individuals, at this point in time, there is not a major difference in terms of selection of therapy orintensity of therapy based on which of the types of myelofibrosis is most accurate.
Determine the risk to the patient of their myelofibrosis.
There are many ways of estimating risk in myelofibrosis, but the most important is to truly get an impact of how lifethreatening the disease might be and, with this, there have been many different papers and studies that have beenconducted, but probably some variation of the Dynamic International Prognostic Scoring System is the most helpful – theDIPSS or the DIPSS plus. With these, several features are assessed to see how the disease is impacting the patient.
The presence of anemia — with an even greater concern if there is red cell transfusion dependence or need forcontinual transfusions of red blood cells; the presence of a high white blood cell count, over 25 x 109/L cells; thepresence of a low platelet count of <100 x 109/L; age over 65; significant constitutional symptoms; blasts in the peripheralblood; and certain chromosomal changes. All of these are important in terms of predicting how life threatening thedisease. With individuals who have none of these features, we expect they might live many years and sometimes inexcess of 10 years or more with the disease. Those that have three or more, their risk for the disease is significantlygreater and could mean that the disease could be life threatening in even just a handful of years. With this, we thengenerate the myelofibrosis risk score, whether they be low risk, intermediate 1, intermediate 2, or high risk.
Determine the symptomatic burden of the disease.
Utiliz ing the questionnaires that are now available on- line that our group helped develop – The MyeloproliferativeNeoplasm Symptom Assessment Form (MPN- SAF), we get an overall sense of the symptomatic impact of the diseaseon the patient, including issues such as fatigue, night sweats, weight loss, fevers, chills, enlargement of the spleen andsymptoms from the spleen. For individuals with significant symptomatic burden this is a major decision point regardingtherapy. For individuals who have no symptoms it is likewise a factor in determining therapy or perhaps lack of need fortherapy.
Determine the possible role and timing of stem cell transplantation.
Stem cell transplantation (bone marrow transplantation, allogeneic stem cell transplantation), all synonyms of oneanother, where we fundamentally give a significant dose of chemotherapy to clean out the bone marrow and givepatients bone marrow from someone else who is a match. This is the only therapy in 2013 that can cure myelofibrosis.
That being said, it is a therapy that has a significant up- front risk, a therapy that requires a match donor, and a therapythat typically is only even a consideration if an individual is 70 or below with rare exceptions of people in their early 70sbeing considered. It is a therapy, that although it can cure the disease, also brings in a risk that a complication can arisefrom transplantation, which could be life threatening or life shortening for a patient who undergoes it. The timing oftransplantation and the choice of transplantation is probably one of the most medically complex decisions a physicianand patient can make together. All of these caveats being said, I do think it is one of the first initial discussion points.
Whether transplant is something that should be considered immediately for people who have incredibly high risk or aremoving toward acute leukemia, for people who should never be considered for transplant because of age, because ofhaving too many other medical problems, or because of their choice, or finally the group that is probably the largest—somewhere in the middle. In other words, if their disease were to progress, then transplant might be considered. Inindividuals who fall in the category of transplant that might be considered in the future—if they progress, if medicaltherapy doesn’t work, if they move toward acute leukemia, I do advise obtaining HLA (human leukocyte antigen) typingon the patient around the time of diagnosis, so we have a sense of whether any of their siblings are potential donorsand that way if the patient progresses unexpectedly, we can move forward with a transplant in a rapid fashion.
Discuss JAK inhibit or t herapy.
Ruxolitinib (Jakafi) is now FDA approved for the therapy of myelofibrosis and was specifically done so on the basis ofimproving symptoms, splenomegaly, and even survival in those individuals with intermediate and high- risk disease.
This has become the standard of care for myelofibrosis, in particular with individuals with a big spleen with lots ofsymptoms who are severely affected. This is the standard of care, in particular, for people who have these difficultiesand are not moving towards stem cell transplantation. There are clinical trials ongoing now using a JAK2 inhibitor prior tostem cell transplantation to see if outcomes might be further improved. People who have low- risk myelofibrosis, JAKinhibitor therapy might be considered for individuals with very significant symptomatic burden. Additionally, interferon hasbeen used with success, both pegylated interferon and standard interferon in low and intermediate- 1- risk myelofibrosisto hopefully try to delay disease progression and improve the status of these patients. This is also undergoing currentclinical trials. People who primarily have difficulties with great anemia in myelofibrosis are in a slightly different category.
Those for whom anemia is the main driver of the disease are excellent candidates for clinical trials trying to improveanemia. Outside of the clinical trial setting, we will consider drugs from the immunomodulatory class, thalidomide andlenalidomide being commercially available. Pomalidomide has recently completed a phase III clinical trial and may beFDA- approved in the future for treating anemia in patients with myelofibrosis.
Patients with progressive myelofibrosis – those that have increasing blasts, those who moved into acute leukemia or arecoming close to acute leukemia.
This is where the disease is particularly difficult and we have used therapies that are proven in myelodysplasticsyndrome for people with increased blasts — az acytidine and decitabine — sometimes to try to help prevent diseaseprogression. Patients in this setting, if they are eligible for stem cell transplant, that is a strong consideration, sometimeswith a need for chemotherapy such as induction chemotherapy in advance.
Fut ure direct ions.
In the future, many more options are going to be added to this list. Several other JAK2 inhibitors are being investigated of which there are several in phase III clinical trials. The furthest along is fedratinib (SAR302503) of which the phase IIIresults will be presented at the American Society of Hematology and may, on the basis of these results, be FDAapproved somewhere in the near future. Others undergoing clinical trial testing in phase III include pacritinib (SB1518)which may have less negative impact on causing anemia or low platelet count, and momelotinib (CYT387) which maynot only have less negative impact on low blood counts, but it may be helpful for anemia. These two drugs need tocomplete their phase III trials before any assessments can be made. Many other JAK2 inhibitors are undergoing testingincluding LY2784544, NS- 018, and results are expected with great enthusiasm. Additionally, there are many combinationstudies ongoing of combinations of ruxolitinib with many agents to see whether further activity (along with anti- fibrosisdrugs such as PRM- 151, or drugs to aid anemia such as danaz ol) can be augmented by the use of this drug; inparticular, in helping anemia or reducing further impact of fibrosis.
Conclusion
I have tremendous hope for my patients with myelofibrosis and for the future. We are at a moment where there has neverbeen a greater emphasis, a greater number of clinical trials, or a greater number of investigators working together to tryto better understand the biology of myelofibrosis, but also to try to come up with better therapies that truly have a greatmeaning and impact in patients with the disease. Additionally, we are fortunate that regarding the issue of stem celltransplantation, our colleagues in that arena continue to investigate new ways to make that process safer and moreeffective from everything from better support of care measures, such as better antibiotics and immunosuppression, tobetter ways of preparing patients for that process.
-Claire Harrison, Hans Hasselbalch Richard Silver, Ruben Mesa

Source: http://www.pvreporter.com/wp-content/uploads/2014/02/mpnjournal.org-How_I_treatMPNs.pdf