High-risk Essential Thrombocythemia Patients Research Articles

Treatment with Pegylated Interferon α (PegIntron) for High-Risk Essential Thrombocythemia: Results of a Phase II Study.

In high risk Essential Thrombocythemia (ET) there is a indication for cytoreductive therapy. However, especially in younger patients long-term use of alkylating agents or hydroxyurea is a matter of concern. Modification of the pharmacokinetic profile of interferon α, a non-leukemogenic agent, through addition of a polyethylenglicol (pegylation) has resulted in slower absorption and lower elimination rate, thus enabling a weekly application with potentially increased compliance compared to conventional interferon α.In this phase II study we evaluate the safety, tolerability and efficacy of pegylated Interferon α (PegIntron, Essex Pharma) in high risk essential thrombocythemia. PegIntron is administered subcutaneously at a starting dose of 50 μg weekly. In patients not achieving a platelet count < 500 G/l after 8–12 weeks, the dosages can be increased by 25 μg/week up to 150 μg/week. Between 12/01 and 09/03 a total of 36 high risk ET patients (either platelet > 1500 G/l, or age> 60 years, or previous ET related complications) were enrolled by a total of 16 centers (16 male and 20 female patients, median platelet count at diagnosis 900 G/l, median age at diagnosis 54 years [range: 24–72 years]). Treatment was indicated because of at least one of the following reasons: Age > 60 years (38%), platelet count > 1500 G/l (36%) or previous ET related complications (50%). 10 patients (28%) were previously treated (hydroxyurea: 8 patients, anagrelide: 2 patients).In this analysis there are 35 of 36 patients evaluable, 1 patient was lost to follow-up. Of these 35 patients, 24 (69%) are still on therapy with PegIntron after a median observation time of 18 months. The individual dosages of PegIntron are shown in table 1. A platelet count < 500 G/l was achieved in 57% of the patients after 3 months and in 75% and 89% after 6 and 12 months, respectively.In 9 patients (26%) therapy was stopped because of drug related side effects (alopecia: 2 patients, arthralgia: 2 patients, flu-like symptoms: 2 patients, psoriasis: 1 patient, depression: 1 patient, diarrhea: 1 patient). In one patient an alternative cytoreductive therapy was initiated because of an insufficient platelet control. One patient suffered from a cerebral stroke and subsequently was taken off PegIntron application. After a median observation time of 18 months, we observed one potentially ET related complication (stroke) during PegIntron therapy so far.These preliminary data indicate the efficacy of PegIntron in the treatment of high risk ET at relatively low doses and reasonable toxicity and safety compared to conventional interferon α. [Display omitted]

Pharmacotherapy of essential thrombocythaemia: economic considerations

The clinical course of essential thrombocythaemia (ET) is mainly outlined by a predisposition to both thromboembolic, and more rarely, haemorrhagic complications. The individual clinical course is, however, variable, ranging from an event-free course to life-threatening thromboembolic episodes. In order to treat ET patients economically, it is necessary, above all, to consider if cytoreductive therapy is really indicated. Risk stratification according to clinical criteria such as age, previous ET-related events and platelet count may help to define patients at risk. In low-risk ET patients, a watch-and-wait strategy seems to be feasible. There is a clear indication for cytoreductive therapy in high risk ET patients as demonstrated in a Phase III clinical trial. Because of the lack of Phase III trials, it is not clear which of the cytoreductive drugs – hydroxyurea, pipobroman, IFN-α, pegylated-IFNs or anagrelide – is the best therapeutic option. Factors that influence the choice out of the available drugs are efficacy, safety and cost. The efficacy and safety data of the available drugs for ET are derived from Phase II studies or observational studies. IFN-α is the most expensive drug. Newer drugs like anagrelide or pegylated-IFNs are still expensive, but may have a better cost-benefit effect in patients < 60 years of age. Two cost-effectiveness analyses revealed a result in favour of anagrelide, however, in these cost-effectiveness models, assumptions were based on non-randomised trials. For patients > 60 years of age, hydroxyurea may be the best therapeutic option with regard to both the efficacy and cost-effectiveness.

Pipobroman is safe and effective treatment for patients with essential thrombocythaemia at high risk of thrombosis.

Essential thrombocythaemia (ET) is a disease associated with an elevated risk of thrombosis. This study evaluated the efficacy and safety of pipobroman (PB) in the long-term control of ET patients who had, at diagnosis, one or more of the following currently known risk factors for thrombosis or haemorrhage (high-risk patients): age > 60 years, history of thrombosis or haemorrhage, platelets >1000 x 10(9)/l. From 1978 to 2000, with a median follow-up of 10 years, 118 previously untreated high-risk ET patients (median age 62 years, range 25-82), were treated with PB at the starting dose of 0.8-1 mg/kg/d. All patients reached a platelet count <600 x 10(9)/l and 91% achieved a platelet count <400 x 10(9)/l. During follow-up, 13 patients had thrombosis, with a 10-year cumulative risk of 14%. Acute myeloid leukaemia, myelofibrosis and solid tumours occurred in three, two and seven patients with a 10-year cumulative risk of 3%, 2% and 7% respectively. Actuarial survival at 20 years was 64% and the standardized mortality ratio was 1.1 (95% CI: 0.7-1.7), not statistically different from the general population (P = 0.54). Age was associated with a higher risk of death (P = 0.00009) and thrombosis (P = 0.003). The duration of PB treatment did not correlate with the occurrence of second malignancies. This study, with a median follow-up of 10 years, demonstrates that pipobroman is effective and well tolerated. The low cumulative 10-year risk of thrombosis, leukaemia and solid tumours indicates that pipobroman is an adequate treatment for patients with high risk ET.

Aspirin and platelet-lowering agents for the prevention of vascular complications in essential thrombocythemia.

Low-risk essential thrombocythemia patients include patients aged 18 to < 80 years with no vascular risk factor or previous thrombosis, no associated disease, a normal life expectancy, and a platelet count between 400 and 1,000 x 10(9)/L up to 1,500 x 10(9)/L. Asymptomatic essential thrombocythemia patients may be at risk for microvascular circulation disturbances. The indication for low-dose aspirin in asymptomatic essential thrombocythemia patients is uncertain, therefore randomization for aspirin 50 mg versus placebo is recommended. Symptomatic essential thrombocythemia patients with erythromelalgia and its ischemic complications, atypical transient ischemic attacks, minor stroke, visual disturbances and "superficial thrombophlebitis" in the absence of bleeding, vascular risk factors, or vascular disease have a clear indication for aspirin in a regular dose. To determine whether 50 mg/day is as effective as 100 mg/day for the prophylaxis of microvascular circulation disturbances in essential thrombocythemia, a randomized trial comparing low-dose aspirin 50 mg versus 100 mg at platelet counts between 400 and 1,000 up to 1,500 x 10(9)/L is recommended. To address the question whether reduction of the platelet count to normal (< 350 x 10(9)/L) is as effective as low-dose aspirin for the long-term relief of microvascular circulation disturbances, a randomized study comparing low-dose aspirin with the correction of platelet count to normal by anagrelide is recommended. High-risk essential thrombocythemia patients have a clear indication for platelet reductive therapy, including: (a) platelets > 1,500 x 10(9)/L, history of major thrombosis (myocardial infarction, stroke, peripheral occlusive vascular disease), or presence of vascular disease (e.g., arteriosclerosis); (b) history or presence of spontaneous or major bleedings, bleedings elicited by low-dose aspirin for the secondary prevention of vascular complications in essential thrombocythemia at platelet counts < 1500 x 10(9)/L, and side effects of long-term aspirin treatment such as gastritis; and progression from low- to high-risk essential thrombocythemia patients during follow-up or progressive myeloproliferative disease such as significant splenomegaly, myelofibrosis, leukocytosis, etc. To address the question of optimal treatment of high-risk essential thrombocythemia patients, randomization for anagrelide versus interferon at < 65 years of age and anagrelide versus hydroxyurea at an age > 65 years is recommended.