Myeloproliferative Neoplasms in Asia, Including Middle East, Turkey, and Algeria: Epidemiological Indices and Treatment Practice Patterns from the Multinational, Multicenter, Observational MERGE Registry
Authors: Yassin Mohamed A , Taher Ali , Mathews Vikram , Hou Hsin-An , Shamsi Tahir , Tuglular Tulin , Xiao Zhijian , Kim Soo-Jeong , Wu Depei , Li Junmin , Rippin Gerd , Sadek Islam , Siddiqui Asif , Wong Raymond S 
Published: October 2019

Abstract
Background
The Philadelphia chromosome−negative classical myeloproliferative neoplasms ([MPNs], including essential thrombocythemia [ET], polycythemia vera [PV], and myelofibrosis [MF]), are generally associated with a substantial disease burden, often leading to a reduced quality of life (QOL) and shortened survival in many patients (pts). There has been a lack of estimates for the incidence/prevalence and treatment patterns of MPNs in many regions of the world, including countries from South Asia, Asia Pacific, Middle East, and Turkey. Hence, there is a need to establish databases like registries, which would provide information on the "real-world" data in these regions. The MERGE registry was initiated with an objective to collect data on the epidemiological indices of MPNs and existing treatment patterns in Asia, including Middle East, Turkey, and Algeria. This primary descriptive analysis from the MERGE registry was performed to estimate the incidence/prevalence, natural disease course, and treatment patterns of MPNs in these countries.
Methods
MERGE is a multinational, multicenter, nonintervention study that included adult pts with MPNs, who were diagnosed according to World Health Organization 2008 criteria. The data were collected retrospectively (since diagnosis) and prospectively after enrollment in the study. Disease assessments were scheduled every 6 months up to 5 visits, with a minimum of 2 years of follow-up. Pts who participated or were participating in a randomized clinical trial were allowed. Data were analyzed descriptively.
Results
In total, 884 MPN pts (ET=373, PV=301, MF=169, and unclassified=41) were included in the full analysis data set. The median age was 58 years (range, 47-66 years; younger compared to other regions) and 50% pts were males. Baseline pt characteristics by MPN subtype are summarized in Table 1. About 57% of pts were diagnosed by incidental finding of abnormal blood results followed by bone marrow evaluation. In these countries, the prevalence and incidence of MPNs are estimated to be 57-81 and 12-15 per 100.000 hospital-patients per year over the last 4 years, respectively.
As assessed by MPN Symptom Assessment Form (MPNSAF), 92% of the pts reported at least 1 symptom. At baseline, fatigue was the most common symptom in all 3 MPN subtypes (71% MPN; 78% MF; 71% ET; and 68% PV). Inactivity (64%), early satiety (61%), abdominal discomfort (57%), bone pain (56%), weight loss (52%), night sweats (46%), and fever (29%) were more common in MF; whereas, itching in PV pts (50%). MF pts had the highest total symptom score at baseline (mean [SD], 23.5 [17.47]) as compared to ET (mean [SD], 14.6 [14.26]) and PV pts (mean [SD], 16.6 [14.84]). Overall, 64% of pts had ECOG performance status of 0 and 26% had ECOG 1.
During study period, the most common nonpharmacological intervention was red cell transfusion in MF and ET pts, and phlebotomy in PV pts. Splenectomy (n=2) and stem cell transplantation (n=4) were rarely employed (6 MF pts). Hydroxyurea (HU) was the most common first-line therapy in all 3 MPN subtypes (overall, 54%; PV, 61%; ET, 54%; and MF, 39%), followed by aspirin. Other common first-line therapies were anagrelide (10%) and interferon (9%) in ET pts, antineoplastic (6%) and clopidogrel (6%) in PV, and JAK2 inhibitors in MF pts (15%). More than 75% of the induction therapies were monotherapies, with less than 3% of pts receiving 3 or more drug combinations as primary treatment. Patients with MF often received monotherapy (81%), than the other patients with MPN. Median duration of first-line therapy was about 6 months (95% CI, 1-21 months), and first-line therapy discontinuation rates of 35%, 36%, and 30% were noted in ET, PV and MF pts, respectively. Interferon was used in 8% of in the second-line setting. JAK2 inhibitors were more frequently (14%-17%) used in the second-and third-line settings.
Conclusions
The prevalence and incidence of MPNs in countries from Asia Pacific were derived using the number of pts visiting the corresponding hospitals. Thus, the resulting incidence and prevalence reported here are not directly comparable with the country-based prevalence/incidence and may overestimate the actual values. At baseline, pts with MPNs had significant disease burden. The most common first-line therapy was HU, though discontinuation rates of first-line therapies were high, and JAK2 inhibitors were mostly used in the second-line/third-line settings.

Disclosures
Yassin: Novartis: Research Funding. Taher:La Jolla Pharmaceutical: Research Funding; Ionis Pharmaceuticals: Consultancy; Celgene Corp.: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Protagonist Therapeutics: Consultancy. Kim:Novartis Korea: Honoraria. Rippin:Employee of IQVIA - doing consultancy for Novartis: Consultancy. Sadek:Novartis Pharmaceutical Corporation: Employment. Siddiqui:Novartis Pharma AG: Employment, Equity Ownership. Wong:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.