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My name is Heinz Gisslinger from the Medical University of Vienna, and I am presenting at the SOHO 2016 meeting about perspectives and future directions in essential thrombocythemia and polycythemia vera.
It's important to have an exact diagnosis, because essential thrombocythemia consists of early myelofibrosis, and WHO classified essential thrombocythemia. It's necessary to perform bone marrow biopsy in order to differentiate early pre-fibrotic myelofibrosis from ET, which is important for a fibrosis-free survival as we have published very recently in leukemia, fibrosis-free survival is superior in WHO classified essential thrombocythemia, in comparison to the British ET classification, and also the overall survival is superior in WHO classified essential thrombocythemia.
What is about the risk factors for a thrombosis in WHO classified essential thrombocythemia? The IPSET-Thrombosis, there are four factors which play a role. The age, beyond sixty years, cardiovascular risk factors, previous thrombosis, and JAK-2 positivity. This slide shows the advised IPSET thrombosis score, published recently. It divides the risk categories to four risks: very low, low risk, intermediate, and high risk.
Very low risk patients with essential thrombocythemia, those with age below sixty, no JAK-2 mutation, no prior thrombotic events. Low risks are those patients below sixty, no prior thrombotic events, but JAK-2 positivity. Intermediate risk of those patients who are beyond sixty years, no JAK-2 mutation, no prior thrombotic event. High risk patients are those with thrombotic events in their history, or beyond sixty, and JAK-2 positivity.
How should we treat these patients? This has been published, or has been shown by a very recent paper from the Spanish group, showing that aspirin has some advantages in avoiding venous thrombotic events in JAK-2 positive patients, but there's no difference in JAK-2 positive patients, are using aspirin, those patients having arterial thrombotic events.
In the calreticulin positive patients, you don't have any beneficial effect from aspirin, but the risk for bleeding in those patients is higher, it does not make sense to use aspirin in calreticulin positive, low risk, essential thrombocythemia patients. What is about the platelet count, and the correlation with thrombosis? There is no correlation of platelet counts at the time of diagnosis, or elevated platelet counts, [inaudible 00:03:33] from thrombotic events, then promote thrombotic events, according to several analyses of this issue.
On the other hand, there are two papers now that show that at the time of thrombotic events, usually the median platelet count is higher, in those patients who had thrombotic events, in comparison to all the measure of platelet counts, during the follow up. The platelet counts plays a role for the appearance of thrombotic events during follow up, which is important.
Dependent from the classification, how the essential thrombocythemia diagnosis was made? According to the British ET criteria, or according to the classic WHO essential thrombocythemia diagnosis criteria, it's dependent which compound you should use. The patients have been diagnosed according to PBSG, it's better to use a cytoreductive therapy, for example, hydroxurea, or also interferon, if possible. On the other hand, in WHO classified essential thrombocythemia it's efficient to use only Anagrelide.
This slide shows the central European guidelines for treatment of essential thrombocythemia, and we show that beyond six hundred thousand platelets, it should be treated with platelet lowering compounds. In our setting we use in essential thrombocythemia, according to the WHO, classified always as first line Anagrelide, and second line hydroxurea, at platelet counts beyond one thousand five hundred, we use hydroxurea as first line in order to prevent bleeding events, because Anagrelide, in very high platelet counts, can promote bleeding in this setting.
What about treatment of polycythemia vera? There is the possibility besides hydroxurea to use interferon in these patients. Interferon has shown to cause high, complete remission rates, concerning hematologic response, and a partial response achieved in almost one hundred percent of the patients after more than one year interferon treatment.
We saw in our phase one, phase two study, that the JAK-2 allelic burden goes down to almost zero in about twenty percent in the treated patients. The alternative is certainly in hydroxurea-resistant patients, this Ruxolitinib is able to create a response rate complete [inaudible 00:06:39] hematological remission in about twenty percent of the patients, and it has a striking effect on the spleen size, and also on the hematocrit level. It improves the constitution of symptoms, improves viscosity, and also improves sometimes mood disorders.
Ruxolitinib is a very convenient compound in those patients who are hydroxurea resistant. This is the sample central European myeloproliferative organization guidelines for treatment of polycythemia vera. In our setting, it's possible to use interferon as first line, and therefore we recommend interferon as first line, hydroxurea in those patients where we cannot use hydroxurea. As second, let's say third line, JAK-2 inhibitors, which only are licensed for those patients who show resistance to hydroxurea, or intolerance to hydroxurea, thank you for your attention.