ImetelChat

It already has been said at other occasions: ET is not so 'innocent' as we may think. This article suggests that there are significantly more PreMF cases amongst ET diagnosed patients than we currently acknowledge. That means that imetelstat may very well play a life saving role for a significant subgroup of ET diagnosed patients, who actually are in the phase of developing MF.

Clinical impact of bone marrow morphology for the diagnosis of essential thrombocythemia: comparison between the BCSH and the WHO criteria
Leukemia Advance Online Publication, Gisslinger et al, 12 February 2016

Essential thrombocythemia (ET) is currently diagnosed either by the British Committee of Standards in Haematology (BCSH) criteria that are predominantly based on exclusion and not necessarily on bone marrow (BM) morphology, or the World Health Organization (WHO) criteria that require BM examination as essential criterion. We studied the morphological and clinical features in patients diagnosed according either to the BCSH (n=238) or the WHO guidelines (n=232). The BCSH-defined ET cohort was re-evaluated by applying the WHO classification. At presentation, patients of the BCSH group showed significantly higher values of serum lactate dehydrogenase and had palpable splenomegaly more frequently. Following the WHO criteria, the re-evaluation of the BCSH-diagnosed ET cohort displayed a heterogeneous population with 141 (59.2%) ET, 77 (32.4%) prefibrotic primary myelofibrosis (prePMF), 16 (6.7%) polycythemia vera and 4 (1.7%) primary myelofibrosis. Contrasting WHO-confirmed ET, the BCSH cohort revealed a significant worsening of fibrosis-free survival and prognosis. As demonstrated by the clinical data and different outcomes between WHO-diagnosed ET and prePMF, these adverse features were generated by the inadvertent inclusion of prePMF to the BCSH group. Taken together, the diagnosis of ET without a scrutinized examination of BM biopsy specimens will generate a heterogeneous cohort of patients impairing an appropriate clinical management.

link: http://www.nature.com/leu/journal/vaop/ ... 5360a.html

fisher - this is an important point. I think that it is generally agreed by MPN experts that imetelstat may not be indicated for all ET patients (risk:reward) but is likely life-saving in pre-MF ET. I have read some studies that suggest research is getting closer to the biomarkers that could better predict liklihood of ET transformation to MF.

When imetelstat is approved for MF, patients diagnosed with preMF-ET will get access to imetelstat also. Even in cases that there may still be some doubts, doctors can easily advocate towards MF diagnosis, certainly if fibrosis is already noticable in the bonemarrow through biopsy, possibly accompanied with elevant LDH and enlarged spleen (both very frequent in ET patients). This further underlines the importance of Baerlocher's ET study outcomes.