Patients with myeloproliferative neoplasms (MPN) who later develop ph+ chronic myelogenous leukemia (CML): A case series.

Abstract

e18563 Background: Myeloproliferative Neoplasms are divided by the presence or absence of the Philadelphia Chromosome. Ph- MPN, typically possess driver mutations of JAK-2, MPL and CALR. CALR is involved with apoptosis and cell proliferation . MPL leads to TPO receptor stimulation and mutations are reported as a known cause of AA. JAK-2 mutations render hematopoietic stem cells more sensitive to growth. Though the true incidence is unknown, there are infrequent reports of pts with ET who later develop CML. CALR, MPL and JAK-2 mutations may have some further role in determining whether these are two separate events or clonally derived. We report three pts with MPN who later developed CML. Methods: Chart Review Results: Pt 1 had ET, diagnosed 21 yrs earlier treated with hydroxyurea. He then developed a rising WBC and platelets which necessitated a marrow which detected Ph+ CML. He was CALR positive. NGS was negative for nondriver mutations. Platelets initially declined from 3 million to 975K with TKI and he achieved a MMR. However, the inability to control his thrombocytosis required the addition of ruxolitinib. Pt 2 was diagnosed with ET and was treated with P32. Nine yrs later CML was diagnosed and TKI administration achieved a MMR. Subsequently, a profound anemia evaluation diagnosed PNH requiring eculizumab without benefit and repeat marrow with NGS revealed a MPLmutation and post-ET myelofibrosis. Pt 3 presented with a JAK-2 positive mutation and Polycythemia Vera. After four yrs of hydroxyurea extreme leukocytosis led to a marrow revealing a diagnosis of Ph+ CML. Dasatinib achieved a prompt MMR. NGS revealed KIT D618 V , coinciding with a diagnosis of systemic mastoytosis (SM). Conclusions: The rare observation of patients with both ET and CML have been reported by others with some recent implications of CALR as a common clone with double-mutant properties of CML. Our patients had a lead time of 21, 9, and 4 yrs, all having different mutations. Pts with MPN who develop unexplained leuko or thrombocytosis should be evaluated for CML.We plan to retrieve archival tissue to perform serial genetic analyses. Further work is required to determine whether these events are stochastic or represents clonal evolution.