Anagrelide-induced cardiomyopathy

Anagrelide-associated Cardiomyopathy and Heart Failure in a Patient with Essential Thrombocythemia: A Case Report and Literature Review

Anagrelide is used worldwide to treat essential thrombocythemia (ET) by reducing platelet counts. Cardiomyopathy and heart failure (HF) are rare but serious complications associated with anagrelide use, although no cases were reported during Japanese Phase I to III studies. A 46-year-old, otherwise healthy, Japanese ET patient developed HF with reduced ejection fraction after 18 months of treatment with 1.0-3.5 mg of anagrelide daily. HF was stabilized with anagrelide withdrawal and guideline-directed HF therapy. The cardiac function returned to normal after six months. This case suggests that anagrelide can cause cardiomyopathy and HF in ET patients, regardless of nationality, comorbid cardiovascular conditions, or therapy duration.

Anagrelide-Induced Supraventricular Tachycardia: A Case Report

Anagrelide is an inhibitor of the phosphodiesterase-3 (PDE-3) enzyme that suppresses megakaryocytes; hence it is used in the treatment of essential thrombocythemia. Anagrelide can cause positive inotropic and chronotropic effects on the cardiovascular system. Its cardiovascular side effects are rare and include palpitations, tachyarrhythmias, cardiomyopathy, angina, and heart failure. We report the case of a 71-year-old female who presented with sudden onset chest pain. Her only outpatient medications included anagrelide and aspirin. She was found to have supraventricular tachycardia (SVT) with aberrancy that responded to beta-blockers. The chest X-ray, computed tomography angiogram (CTA), and echocardiogram were unremarkable. Her arrhythmia may be attributed to the anagrelide in the absence of any cardiovascular findings.

Ventricular tachyarrhythmia in a 78-year-old woman with essential thrombocythaemia

Anagrelide is a phosphodiesterase-3 inhibitor used in the treatment of essential thrombocythaemia. Cardiovascular side effects such as ventricular tachycardia and cardiomyopathy are rare but potentially fatal and should be made known to patients before starting the medication. It usually arises within the first 6 months after initiation of therapy and may be dose related. The elderly population are particularly susceptible. These cardiotoxicities result from an increase in cyclic AMP that induces positive inotropic and chronotropic effects and are often reversible with cessation of use. We report a case of a 78-year-old woman with essential thrombocythaemia and recently started on anagrelide who presented with syncope and multiple bruises and facial trauma and found to have developed ventricular tachyarrhythmia.

A Case of Anagrelide-Induced Nonischemic Cardiomyopathy in a Patient With Essential Thrombocythemia

BACKGROUND

Anagrelide is an established treatment option for essential thrombocythemia (ET). Cardiovascular adverse events can occur with its use including heart failure and cardiomyopathy.

CASE REPORT

A 52-year-old African American male with ET presented with chest pain, shortness of breath, and dyspnea on exertion. His ET was managed with hydroxyurea 1500 mg by mouth twice a day and anagrelide 1 mg by mouth 3 times a day. The patient was receiving anagrelide for approximately 2 years prior to presentation. The patient's platelet count was 2.07 × 10⁵ cells/mm³. Transthoracic echocardiography revealed decreased left systolic dysfunction. Also, cardiac magnetic resonance imaging showed an increased left ventricle cavity size with severely depressed systolic dysfunction and an ejection fraction (EF) of 18%. Anagrelide therapy was discontinued and the patient was maintained on hydroxyurea for ET. Three months later, following treatment by a heart failure clinic, the patient's EF was 55%. Five months after discontinuation, the patient improved from New York Heart Association (NYHA) class II to NYHA class I.

CONCLUSION

A 52-year-old man with ET presented with an EF of 18% after 2 years of anagrelide therapy. His EF increased from 18% to 55% 3 months after discontinuation of anagrelide.

Anagrelide: an update on its mechanisms of action and therapeutic potential

Thrombocytosis is an increasingly recognized clinical problem due to the widespread availability of automated cell counters. While reactive thrombocytosis does not require any therapeutic intervention, clonal thrombocytosis may require therapy to prevent thrombohemorrhagic complications. The clinician has a number of therapeutic options available when confronted with a patient having clonal thrombocytosis. One of these agents is anagrelide (Agrylin, Bristol-Myers Squibb). In this drug profile, a synopsis of the available data on this agent and its role in the control of thrombocytosis will be provided. The main side effects of the medication are discussed, as well as the potential future developments in the field.

Cardiovascular safety of anagrelide in healthy subjects: effects of caffeine and food intake on pharmacokinetics and adverse reactions

Background

Essential thrombocythaemia (ET) is a rare clonal myeloproliferative disorder characterized by a sustained elevation in platelet count and megakaryocyte hyperplasia. Anagrelide is used in the treatment of ET, where it has been shown to reduce platelet count. Anagrelide is metabolized by cytochrome P450 (CYP) 1A2, and previous studies of the effect of food on the bioavailability and pharmacokinetics of anagrelide were conducted prior to the identification of the active metabolite, 3-hydroxyanagrelide.

Objectives

The objectives of this study were to determine the effect of food and caffeine on the pharmacokinetics of anagrelide and its active metabolite, 3-hydroxyanagrelide, to monitor electrocardiogram (ECG) parameters following drug administration, and to document the relationship between palpitations, ECG changes and caffeine intake

Methods

Thirty-five healthy subjects who received 1 mg of anagrelide following either a 10-h fast or within 30 min of a standardized breakfast, including two cups of coffee, were studied.

Results

Time to maximum (peak) plasma concentration (C_max) of anagrelide was 4.0 h in the fed and 1.5 h in the fasted group (p < 0.05); similar results were observed for 3-hydroxyanagrelide. The mean C_max of anagrelide was 4.45 ± 2.32 ng/mL and 5.08 ± 2.99 ng/mL in the fed/caffeine and fasted groups, respectively; peak concentrations were higher for 3-hydroxyanagrelide in both the fed/caffeine and fasted groups. The most frequent adverse events (AEs) were headache (60 %) and palpitations (40 %). There were no serious AEs and all ECGs were normal, although significant reductions in PR interval, QRS length and QT interval were observed in both groups. Heart rate increased after anagrelide administration in both fed/caffeine and fasted states (p < 0.01); however, increased heart rate was significantly more frequent in the fed/caffeine state than in the fasted state (p < 0.001 for heart rate increase in the first hour after drug administration). There was a trend towards a greater heart rate increase in subjects reporting palpitations than in those without (mean heart rate ± SD at 1 h: 10.1 ± 6.4 vs. 8.0 ± 8.4 beats/min [p = 0.35]; at 4 h: 12.7 ± 7.5 vs. 9.1 ± 8.8 beats/min [p = 0.10], respectively).

Conclusion

We conclude that food/caffeine delayed absorption of anagrelide. Anagrelide was generally well tolerated and had small effects on ECG parameters and heart rate. Caffeine may be implicated in a higher increase in heart rate and increased frequency of palpitations observed following administration of anagrelide with food/caffeine versus fasting.

Low impact of cardiovascular adverse events on anagrelide treatment discontinuation in a cohort of 232 patients with essential thrombocythemia

This retrospective study of the thrombocythemia Italian registry (RIT) documented that 71 (30.6%) out of 232 ET patients experienced 88 cardiovascular adverse events (CV-AEs) during anagrelide treatment (522 pt-y). The rate of CV-AEs was: 24.1% for palpitations, 4.3% for angina, 3.5% for arterial hypertension, 3.0% for congestive heart failure, 1.8% for arrhythmia, 0.9% for AMI, 0.4% for pericardial effusion. CV-AEs led to treatment discontinuation in nine (3.9%) patients, while in the remaining cases they were managed by pharmacological intervention and/or patient life style improvement. CV-AEs had no relationship with patient characteristics (including older age). A significant relationship was found only with a higher anagrelide induction dose. In the absence of any agreed protocol, a cardiovascular instrumental evaluation (CV-IE) was performed in 102 (44%) patients before commencement of anagrelide (with higher rate after the anagrelide/Xagrid EMA approval of 2004), and in 84 (36%) patients during treatment. Patients with and without CV-IEs, who resulted completely balanced for all their characteristics, did not significantly differ in the occurrence of CV-AEs. In conclusion, this study on ET patients treated with anagrelide shows that CV-AEs, equally distributed in younger and older subjects, were mostly mild and easily manageable, allowing safe treatment continuation in the majority of cases. Moreover, routinely performing a CV-IE did not appear to anticipate the occurrence of CV-AEs.

A critical review of anagrelide therapy in essential thrombocythemia and related disorders

Thrombocytosis is a common clinical problem and it represents either a primary myeloid disorder (a clonal process) or a reactive phenomenon. While reactive thrombocytosis is often inconsequential, clonal thrombocytosis may require cytoreductive therapy to prevent thrombohemorrhagic complications. In this regard, a controlled clinical trial has previously demonstrated the efficacy of hydroxyurea in reducing the risk of thrombosis in high-risk patients with essential thrombocythemia (ET). Despite the absence of similar evidence for clinical benefit, the platelet-lowering agent anagrelide has been widely used in both ET and polycythemia vera (PV) and recent reports of serious side-effects suggest that such practice might be detrimental to patients. In the current review we provide basic drug information as well as a critical assessment of anagrelide treatment in ET and related disorders.

Pharmacokinetics, bioequivalence, tolerability, and effects on platelet counts of two formulations of anagrelide in healthy volunteers and patients with thrombocythemia associated with chronic myeloproliferation

BACKGROUND

Anagrelide hydrochloride is an anti-thrombotic agent indicated for the treatment of essential thrombocythemia (ET). In various previously published clinical trials of 2 branded formulations of anagrelide in patients with ET at high risk for thrombohemorrhagic events, the rates of adverse events and discontinuation were strikingly divergent between brands. Because the formulations and manufacturers differed, the differences in tolerability, as well as platelet counts, might have been related to differences in pharmacokinetic properties between the 2 formulations.

OBJECTIVES

The present series of investigations (1) determined the pharmacokinetic profile of anagrelide and its metabolites; (2) compared the pharmacokinetic profiles of the test and reference formulations of anagrelide; (3) investigated the in vitro release of anagrelide as a marker of intragastric anagrelide release of the test and reference formulations; and (4) compared the platelet-reducing effects of the test and reference formulations in patients with thrombocythemia in 2 longitudinal studies over 4 weeks.

METHODS

A series of 4 in vivo studies and 1 in vitro study were conducted. In a pilot, prospective, singledose study in healthy volunteers, the pharmacokinetic properties (C(max), T(max), and AUC(0-infinity)) of a test formulation of anagrelide were assessed using high-performance liquid chromatography analysis of plasma samples. Based on the results from that study, a single-dose, randomized, double-blind, 2-period crossover study in healthy volunteers was conducted to determine bioequivalence of 2 formulations of anagrelide 2 mg/d (taken as 4 capsules). In vitro dissolution properties of the test or reference formulation containing 0.5 mg anagrelide as the active ingredient were studied in an assay mimicking gastrointestinal release. To test for effects on platelet counts of switching from the reference formulation (previous treatment on stable dose for 3 months) to the test formulation, two 4-week longitudinal trials were conducted: one in patients with ET (in Germany), and one in patients with thrombocythemia associated with chronic myeloproliferative disorders (CMPDs) (in Austria).

RESULTS

The pilot pharmacokinetic study of the test formulation in 16 volunteers (10 women, 6 men; mean [SD] age, 20.5 [1.5] years; weight, 69.0 [10.0 kg) suggested that anagrelide was metabolized to 3-hydroxyanagrelide (AUC(0-infinity) 50% compared with anagrelide) and the inactive metabolite 2-amino-5,6-dichloro-,4-dihydroquinazolone. The subsequent bioequivalence study in 24 volunteers (14 women, 10 men; mean [SD] age, 23 [4] years; white, 100%; weight, 67.5 [10.2] kg) found that the test formulation was associated with a significantly lower C(max) (point estimation [PE], 66%; 90% CI, 58%-76%; P < 0.001) and AUC(0-infinity) (PE, 77%; 90% CI, 68%-86%; P = 0.001). T(max) values for anagrelide and 3-hydroxyanagrelide were 1 hour longer with the test formulation compared with the reference formulation. The total number of adverse events with the reference formulation was 46; the test formulation, 29 (P = 0.05). In vitro, anagrelide from the reference formulation was immediately released (89.1% at 5 minutes), whereas there was a delayed release (93.6% at 30 minutes) from the test formulation (P < 0.05). In the last 2 studies, 2 cohorts of white patients (cohort 1, 15 patients with ET; 10 women, 5 men; mean [SD] age, 49.0 [10.7] years [range, 31-66 years]; weight, 73.2 [12.6] kg; cohort 2, 19 patients with thrombocythemia associated with CMPD; 12 women, 7 men; age, 62.6 [12.4] years [range, 38-80 years]; weight, 66.1 [13.3] kg) who had received treatment for > or =3 months with the reference formulation were switched to the same dose of the test formulation and maintained on this dose for 4 weeks. Platelet counts did not change significantly from baseline over 4 weeks and stayed within a predefined margin of 150 x 10(3) cells/microL.

CONCLUSIONS

The pharmacokinetic properties, adverse event rates, and in vitro dissolution profile differed between the test and reference anagrelide formulations in these healthy volunteers. In patients with ET or thrombocythemia associated with CMPD, platelet counts did not differ significantly from baseline at 4 weeks when subjects were switched from the reference to the test anagrelide formulation.

Anagrelide: a review of its use in the management of essential thrombocythaemia

Anagrelide (Agrylin, Xagrid) is an oral imidazoquinazoline agent which is indicated in Europe for the reduction of elevated platelet counts in at-risk patients with essential thrombocythaemia who are intolerant of or refractory to their current therapy, and in the US for the reduction of elevated platelet counts and the amelioration of thrombohaemorrhagic events in patients with thrombocythaemia associated with myeloproliferative disorders. Anagrelide is well established as an effective platelet-lowering agent in most patients with essential thrombocythaemia, including both treatment-naive patients and those refractory to other cytoreductive therapy. Results of the only randomised trial to date (the Primary Thrombocythaemia 1 [PT1] study) indicated that the composite primary endpoint (arterial or venous thrombosis, serious haemorrhage or death from vascular causes) occurred more often in recipients of anagrelide plus aspirin than in those receiving hydroxycarbamide (hydroxyurea) plus aspirin. This trial also indicated that the incidence of the secondary endpoints transient ischaemic attack and gastrointestinal bleeding favoured hydroxycarbamide plus aspirin, while the incidence of venous thrombosis favoured anagrelide plus aspirin. There were no differences between the groups in the incidence of secondary endpoints myocardial infarction, stroke, unstable angina, pulmonary embolism, hepatic-vein thrombosis, other serious haemorrhage or related deaths. The design of the PT1 study has been queried with respect to the heterogeneous nature of the study population (possible inclusion of patients with early myelofibrotic disease) and the concomitant use of aspirin (interaction with anagrelide causing increased bleeding events). Further data are therefore required before the role of anagrelide in essential thrombocythaemia can be finalized. In the meantime, when considering treatment options for patients with this disorder, anagrelide's positive effects on platelet function, lack of mutagenicity and lack of association with leukaemia or angiogenesis must be balanced against its comparative expense and positive inotropic effects. Thus, the role of anagrelide in the management of high-risk patients with essential thrombocythaemia will ultimately depend on individual patient assessment and future clarification of the potential leukaemogenicity of hydroxycarbamide.

Anagrelide: a decade of clinical experience with its use for the treatment of primary thrombocythaemia

Primary thrombocythaemia (PT) is the most frequent among the rare chronic myeloproliferative disorders. Life expectancy is determined by thromboembolic and haemorrhagic complications, which can be prevented by cytoreductive therapy. For a long time, hydroxyurea has been considered as the therapeutic gold standard. However, hydroxyurea treatment is not lineage-specific, may not be tolerated because of adverse effects (skin, gastrointestinal tract) and is leukaemogenic when sequentially used with other DNA-targeting drugs. Hence, anagrelide was welcomed in 1988 when it was first described as being efficient at normalising elevated platelet counts, specific for megakaryocytes and non-mutagenic. Since then, anagrelide has been approved in the US and Canada (Agrylin), Shire Pharmaceuticals) as well as in Austria and other countries of the EU (Thromboreductin), AOP Orphan Pharmaceuticals). Clinical Phase III trials (PT1 and ANAHYDRET) are underway to directly compare the efficacy and safety of anagrelide and hydroxyurea.

Severe hypersensitivity pneumonitis associated with anagrelide

OBJECTIVE

To report a case of severe life-threatening hypersensitivity pneumonitis temporally associated with the use of anagrelide in a patient with myeloproliferative disorder.

CASE SUMMARY

A 60-year-old white woman with chronic myeloid leukemia who had been treated with hydroxyurea for 7 years was offered anagrelide to control thrombocytosis. She developed severe hypersensitivity pneumonitis soon after the drug was initiated and required intubation and mechanical ventilation. A high-resolution computed tomography scan of the chest demonstrated extensive multifocal ground glass attenuation and patchy alveolar consolidation involving both lungs. Bronchoalveolar lavage revealed a preponderance of lymphocytes, suggesting hypersensitivity phenomenon, but was otherwise negative for malignancy and other causes of interstitial pneumonitis. An objective causality assessment revealed that an adverse drug event was probable. Discontinuation of anagrelide and hydroxyurea, and institution of corticosteroid therapy resulted in dramatic improvement.

DISCUSSION

To our knowledge, this is the first case report of severe hypersensitivity pneumonitis closely related to anagrelide therapy. Pulmonary infiltrates have rarely been noted in patients treated with anagrelide. Anagrelide does not depress white blood cell production, causes mild anemia, and is devoid of the leukemogenic potential characteristic of radioactive phosphorus and other alkylating agents. Common adverse effects to anagrelide include headache, nausea, diarrhea, peripheral edema, and palpitations. Frank congestive heart failure and cardiomyopathy have occurred in a small number of patients, but severe pulmonary adverse effects have not emerged as a frequent problem.

CONCLUSIONS

Vigilance is advised in patients who develop dyspnea while taking anagrelide and hydroxyurea. Healthcare providers need to be aware of the possibility of the development of serious life-threatening hypersensitivity pneumonitis. These patients may benefit from serial chest X-rays, pulmonary function testing, and echocardiography.

Anagrelide metabolite induces thrombocytopenia in mice by inhibiting megakaryocyte maturation without inducing platelet aggregation

OBJECTIVE

The mechanism for anagrelide's potent platelet lowering activity in human subjects is not well defined. Studies related to anagrelide function have been hampered by its lack of activity in nonhuman primates and water insolubility. In an effort to define the mechanism whereby anagrelide exerts its therapeutic effect, we identified a water-soluble metabolite (anagrelide.met). The availability of anagrelide.met allowed, for the first time, parallel in vitro and in vivo animal studies centered on the mechanisms by which anagrelide lowers platelet levels.

MATERIALS AND METHODS

The effects of anagrelide.met on proliferation and maturation of mega-karyocytes (MKs) as well as platelet production were studied both in vitro and in vivo.

RESULTS

Anagrelide.met is capable of blocking in vitro MK migration by 20% to 40%. At 100 ng/mL, anagrelide.met selectively blocked in vitro MK maturation, resulting in a 50% decrease in the total number of CD41a(+) MKs, corresponding with a 30% decrease in MK ploidy by day 10 and a 60% decrease by day 20. Daily intraperitoneal injections of anagrelide.met 100 microg into BALB/c mice was sufficient to significantly decrease platelet counts within 24 to 48 hours, stabilizing to 40 to 50% of normal levels by day 5. This was associated with a 45% decrease in the number of developing MKs and an increase in thrombopoietin levels. Anagrelide.met did not alter WBC counts, hematocrit, or bleeding time, or lead to any apparent signs of toxicity. Furthermore, unlike the parent anagrelide compound, anagrelide.met did not inhibit ADP-induced platelet aggregation even at high concentrations (10 microg/mL).

CONCLUSIONS

We describe a cross-species reactive anagrelide metabolite that selectively inhibits MK maturation and migration, lowering platelet levels without influencing platelet aggregation.