Response criteria for myelofibrosis
International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) response criteria
|Complete remission (CR)||All of the following criteria should be met:
|Partial remission (PR)||All CR criteria met except bone marrow histologic remission|
|Clinical improvement (CI)||At least one of the following for at least 8 weeks, in the absence of progressive disease, or complete or partial remission:
|Progressive disease (PD)||At least one of the following: (5)
|Stable disease||None of the above|
|Relapse||Patient previously meeting criteria CI, PR or CR no longer meets criteria for CI|
(1) Because peripheral blood film analysis is subjective, CR does not require absence of morphologic abnormalities of red cells, platelets, and neutrophils
(2) In patients with CR and a pre-existing cytogenetic abnormality, complete cytogenetic response is deﬁned as failure to detect the abnormality in at least 20 metaphases. Partial cytogenetic response is deﬁned as ≥ 50% reduction in abnormal metaphases. Major molecular response is deﬁned as absence of a previously-positive speciﬁc disease-associated mutation in peripheral blood.
(3) Transfusion-dependence is deﬁned as a transfusion of at least 2 units of red blood cells in the previous month for a hemoglobin < 8.5 g/dL not due to clinically overt bleeding. During therapy within clinical trials, transfusions for a hemoglobin ≥ 8.5 g/dL is therefore discouraged unless clinically indicated.
(4) In splenectomized patients, palpable hepatomegaly is substituted, with the same measurement criteria.
(5) Worsening cytopenias were not included as a criterion for progressive disease because of the difﬁculty differentiating between disease-associated cytopenias and drug-induced myelosuppression. However, ≥ 2 g/dL decrease in hemoglobin, ≥ 100% increase in transfusion requirement, or new development of transfusion dependence, each lasting for > 3 months after discontinuation of protocol therapy, can be considered disease progression.
These International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) response criteria were published in 2006.1