Cytogenetic abnormalities in essential thrombocythemia at presentation and transformation

Genetic alterations in myeloproliferative and myelodysplastic/myeloproliferative neoplasms - a practical guide to WHO-HAEM5

Within the World Health Organization (WHO) classification of haematopoietic neoplasms, particularly its fifth version from 2022 (WHO-HAEM5), myeloid neoplasms are not only grouped into myeloproliferative (MPN) and myelodysplastic neoplasms (MDS). There is also a group of haematological disorders that share features of both categories termed myelodysplastic /myeloproliferative neoplasms (MDS/MPN). In this article, we aim to provide a comprehensive and practical guide to WHO-HAEM5 highlighting the genetic alterations that underlie MPN and MDS/MPN. This guide provides an overview of the overlapping commonalities among these entities, as well as their unique characteristics.

Essential Thrombocythemia and Post-Essential Thrombocythemia Myelofibrosis: Updates on Diagnosis, Clinical Aspects, and Management

Although several decades have passed since the description of myeloproliferative neoplasms (MPN), many aspects of their pathophysiology have not been elucidated. In this review, we discuss the mutational landscape of patients with essential thrombocythemia (ET), prognostic scores and salient pathology, and clinical points. We discuss also the diagnostic challenges of differentiating ET from prefibrotic MF. We then focus on post-essential thrombocythemia myelofibrosis (post-ET MF), a rare subset of MPN that is usually studied in conjunction with post-polycythemia vera MF. The transition of ET to post-ET MF is not well studied on a molecular level, and we present available data. Patients with secondary MF could benefit from allogenic hematopoietic stem cell transplantation, and we present available data focusing on post-ET MF.

Cytogenetic abnormalities in essential thrombocythemia: Clinical and molecular correlates and prognostic relevance in 809 informative cases

Cytogenetic studies among 809 consecutive patients with essential thrombocythemia (ET; median age 59 years; 65% females) revealed normal karyotype in 754 (93%), loss of chromosome Y only (-Y) in 16 (2%), and abnormalities other than -Y in 39 (4.8%), the most frequent being sole 20q- (n = 8). At presentation, abnormal karyotype, excluding -Y, was associated with older age (p = 0.04), higher leukocyte count (p = 0.03) and arterial thrombosis history (p = 0.02); no associations were apparent for JAK2/CALR/MPL mutations whereas ASXL1 mutations clustered with normal karyotype/-Y and TP53 with abnormal karyotype. Survival was significantly shorter in patients with abnormal karyotype or -Y, compared to those with normal karyotype (median 12, 10, and 21 years, respectively; p < 0.0001). During multivariable analysis that included IPSET (international prognostic score for ET) variables, abnormal karyotype (p < 0.01, HR 2.0), age >60 years (p < 0.01, HR 4.5), leukocytosis >11 × 10⁹/L (p < 0.01, HR 1.5), and male gender (p < 0.01, HR 1.4) were independently associated with inferior survival; abnormal karyotype and age >60 years remained significant, along with SF3B1/SRSF2/U2AF1/TP53 mutations (p = 0.04; HR 2.9), when the latter was included in the multivariable model. The current study suggests prognostic relevance for karyotype in ET.

The Prognostic Role of Cytogenetics Analysis in Philadelphia Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized collectively by clonal proliferation of myeloid cells with variable morphologic maturity and hematopoietic efficiency. Although the natural history of these neoplasms can be measured sometimes in decades more than years, the cytogenetics analysis can offer useful information regarding the prognosis. Cytogenetics has a well-established prognostic role in acute leukemias and in myelodysplastic syndromes, where it drives the clinical decisions. NGS techniques can find adverse mutations with clear prognostic value and are currently included in the prognostic evaluation of MPNs in scores such as MIPSS, GIPSS, MIPSS-PV, and MIPSS-ET. We suggest that cytogenetics (considering its availability and relative cost) has a role regarding prognostic and therapeutic decisions.

Myeloid neoplasm with isolated del(5q) and the MPLW515L mutation fulfills the WHO diagnostic criteria for ET

A 70-year-old male was referred to our hospital for marked thrombocytosis without anemia. The patient simultaneously presented with an MPL W515L mutation, one of the major driver mutations in essential thrombocythemia (ET), and deletion of 5q, a characteristic cytogenetic abnormality in myelodysplastic syndrome (MDS). Bone marrow examination showed a combination of both mature hyperlobulated megakaryocytes, as found in ET, and small hypolobulated megakaryocytes, typically found in MDS with del(5q). The present case is consistent with the recently proposed category of myeloid neoplasms with isolated del(5q) and an MPN driver mutation.

Cytogenetic evolution in myeloproliferative neoplasms with different molecular abnormalities

We investigated the changes in chromosomal abnormalities in myeloproliferative neoplasm (MPN) patients during long-term follow-up. In total, 28 MPN patients (22 with primary myelofibrosis and 6 with polycythemia vera) were included. Among them, 25 patients underwent serial bone marrow (BM) biopsies during disease progression, and 3 patients had cytogenetic abnormalities at initial diagnosis but lacked follow-up BM biopsies. JAK2, CALR, and MPL mutation analyses were performed. Targeted sequencing analysis was conducted in 11 patients. Among the 28 patients, 21 (75.0%) had cytogenetic abnormalities either at diagnosis (8/26) or during follow-up. The median time from the initial analysis to the appearance of additional cytogenetic abnormalities was 8.4 years. Among the chromosomal abnormalities at initial diagnosis, trisomy 8 (3/26, 11.5%) was the most frequent, followed by gain of 1q, del(20q), and del(9q) (each in 2/26). Among all chromosomal abnormalities, including those that occurred during follow-up, the most frequent was del(20q) and +1q (8/28, 28.6%), followed by del(6p) (14.3%) and trisomy 8 (10.7%). Del(20q) was more frequent in CALR-mutated patients (4/6, 66.7%) than in JAK2-mutated patients (3/19, 15.8%, P = 0.016). The presence of cytogenetic abnormalities at initial diagnosis was associated with poor prognosis. Cytogenetic evolution may provide interesting insights into the disease course.

Treatment With JAK Inhibitors in Myelofibrosis Patients Nullifies the Prognostic Impact of Unfavorable Cytogenetics

INTRODUCTION

In the era before Janus kinase (JAK) inhibitors, cytogenetic information was used to predict survival in myelofibrosis patients. However, the prognostic value of cytogenetics in the setting of JAK inhibitor therapy remains unknown.

PATIENTS AND METHODS

We performed a retrospective analysis of 180 patients with bone marrow biopsy-proven myelofibrosis from 3 US academic medical centers. We fit Cox proportional hazards models for overall survival and transformation-free survival on the bases of 3 factors: JAK inhibitor therapy as a time-dependent covariate, dichotomized cytogenetic status (favorable vs. unfavorable), and statistical interaction between the two. The median follow-up time was 37.1 months.

RESULTS

Among patients treated with best available therapy, unfavorable cytogenetic status was associated with decreased survival (hazard ratio = 2.31; P = .025). At initiation of JAK inhibitor therapy, unfavorable cytogenetics was (nonsignificantly) associated with increased survival compared to favorable cytogenetics (hazard ratio = 0.292; P = .172). The ratio of hazard ratios was 0.126 (P = .034). These findings were similar after adjusting for standard clinical prognostic factors as well as when measured against transformation-free survival.

CONCLUSION

The initiation of JAK inhibitor therapy appears to change the association between cytogenetics and overall survival. There was little difference in survival between treatment types in patients with favorable cytogenetics. However, the use of JAK inhibitor therapy among patients with unfavorable cytogenetics was not associated with worse survival compared to favorable cytogenetics. Our analyses suggest that initiation of JAK inhibitor therapy nullifies the negative prognostic implication of unfavorable cytogenetics established in the pre-JAK inhibitor therapy era.

Significance of cytogenetic abnormalities in patients with polycythemia vera

We analyzed 133 patients with polycythemia vera (PV) who were followed at our institution (median 7.5 years) and had adequate cytogenetics information. The 5-, 10- and 15-year survival rates were 93%, 79% and 64%, respectively, with a median projected overall survival of 24 years. Nineteen patients (14%) had abnormal cytogenetics at any time during the disease course (no survival difference). Sixteen patients (12%) underwent disease transformation during follow-up, after a median of 8.5 years, to myelofibrosis (n = 11), acute myeloid leukemia (n = 4) or myelodysplastic syndrome (n = 1); eight had cytogenetic abnormalities. Among 133 patients, 39 were newly diagnosed: 33 with normal and six with abnormal cytogenetics (no survival difference); nine underwent disease transformation (six with normal and three with abnormal cytogenetics at diagnosis). In keeping with other smaller series, the presence of chromosomal abnormalities may have had a role in disease transformation in patients with PV; survival was not affected likely due to short follow-up.