Revised response criteria for polycythemia vera and essential thrombocythemia:an ELN and IWG-MRT consensus project

Standardized response criteria to interpret and compare clinical trials are needed for approval of new therapeutic agents by regulatory agencies. The European LeukemiaNet (ELN) response criteria for essential thrombocythemia (ET) and polycythemia vera (PV) issued in 2009 have been widely adopted as end points in a number of recent clinical trials. However, evidence exists that they do not predict response or provide clinically relevant measures of benefit for the patients. This article presents revised recommendations for assessing response in ET and PV provided by a working group established by ELN and International Working Group-Myeloproliferative Neoplasms Research and Treatment. New definitions of complete and partial remission incorporate clinical, hematological, and histological response assessments that include a standardized symptom assessment form and consider absence of disease progression and vascular events. We anticipate that these criteria will be adopted widely to facilitate the development of new and more effective therapies for ET and PV.

Clinical end points for drug treatment trials in BCR-ABL1-negative classic myeloproliferative neoplasms: consensus statements from European LeukemiaNET (ELN) and Internation Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT)

The discovery of somatic mutations, primarily JAK2V617F and CALR, in classic BCR-ABL1-negative myeloproliferative neoplasms (MPNs) has generated interest in the development of molecularly targeted therapies, whose accurate assessment requires a standardized framework. A working group, comprised of members from European LeukemiaNet (ELN) and International Working Group for MPN Research and Treatment (IWG-MRT), prepared consensus-based recommendations regarding trial design, patient selection and definition of relevant end points. Accordingly, a response able to capture the long-term effect of the drug should be selected as the end point of phase II trials aimed at developing new drugs for MPNs. A time-to-event, such as overall survival, or progression-free survival or both, as co-primary end points, should measure efficacy in phase III studies. New drugs should be tested for preventing disease progression in myelofibrosis patients with early disease in randomized studies, and a time to event, such as progression-free or event-free survival should be the primary end point. Phase III trials aimed at preventing vascular events in polycythemia vera and essential thrombocythemia should be based on a selection of the target population based on new prognostic factors, including JAK2 mutation. In conclusion, we recommended a format for clinical trials in MPNs that facilitates communication between academic investigators, regulatory agencies and drug companies.