Diagnosis and Treatment of MPN in Real Life - Interim-Analysis of an Exploratory Chart Review on 960 ET and MF Patients in Germany

Recommendations for diagnosis and treatment of patients with MPN are well established. However, revision of the WHO classification in 2017 resulted in re-classification of patients’ diagnoses, specifically those previously classified as essential thrombocythemia (ET) or myelofibrosis (MF). While most multicenter trials, investigating therapeutic strategies for ET and MF, have been developed and conducted at specialized academic centers, the majority of patients in Germany is treated in an outpatient (ambulatory) setting. The aim of this study is to evaluate the real life situation: clinical characteristics, diagnosis, risk stratification and treatment decisions. Data was analyzed from a survey conducted at private practices (office-based hematologists).

Eligible practices treating MPN patients in Germany were recruited to participate in an ongoing paper-pencil based survey conducted from Apr 2021-May, 2022. Patients had to be diagnosed after the publication of the revised WHO classification in 2016. Hematologists were asked to report from patient charts. Descriptive analyses were conducted to assess for therapeutic interventions and outcomes (examined by reported prognostic risk scores, symptom scores and clinical response criteria).

For this analysis (data cut-off May 31, 2022) data of 960 patients diagnosed with ET (n=495) or MF (n=465) was provided. As expected, patients showed a female predominance for ET (55.4% female vs. 44.6% male), while it was balanced for MF (50.5% female vs. 49.5% male). Most patients were of older age in both the ET- (63.4% >65y) and MF- (76.4% >65y) cohorts, respectively.

Regarding the diagnostic assessment of ET patients, only 58.6% (n=290) received a bone marrow (BM)-biopsy at primary diagnosis. Among those patients classified as ET, 22.8% (n=113) had splenomegaly (>11cm diameter, and 1% by palpation). 80.4% (n=398) were diagnosed with elevated LDH (above upper normal limit), 3.6% (n=18) with circulating blasts, 27.1% (n=134) with elevated WBC (>11Gpt/l), 12.5% (n=62) with mild anemia (Hb≥10g/dl and <12g/dl) and 2% (n=10) with severe anemia (Hb<10g/dl). Overall, the majority of patients classified as ET revealed at least 1 minor criterium indicative for MF without having received histopathological BM diagnostics. Patients classified as MF were more frequently diagnosed with splenomegaly >11cm diameter (58,5%; n=272 or 22,4%; n=61 by palpation), peripheral blasts (13.8%; n=64), leukocytosis (42.4%; n=197) or anemia (36.2%, n=168; 14%, n=65 with severe anemia Hb<10g/dl) and received histopathologic assessment of the BM in 91.8% of the cases (n=427).

Regarding risk classification of MF, only 35% (n=164) of patients received risk score assessment at diagnosis. Most frequent scoring systems included IPSS (n=62), DIPSS (n=40), DIPSSplus (n=27) and MYSEC-PM (n=19). Molecular scores were used in <8% of cases. 25% of the patients presented as low-risk, 42% as intermediate-1, 21% as intermediate-2 and 12% as high-risk. Of note, a prognosis score was only determined again in 12,9% (n=60) of patients during the course of the disease.

Watch and wait was the primary treatment choice for 21.6% of ET (n=107) and 22.6% of MF (n=105) patients, while 2.4% (n=12) and 8.4% (n=39) were transfusion dependent, respectively. Regarding pharmacologic cytoreduction, 84.7% of ET patients received hydroxycarbamide (HC) after diagnosis and 56,8% were treated with anticoagulants. Likewise, 53.1% of MF patients received HC therapy after diagnosis and 38.1% were treated with anticoagulants. 62.4% of MF patients had elevated platelet counts (>450 Gpt/l) at diagnosis. Regarding symptom-oriented therapy, 40.4% (n=118) of patients received JAK-inhibitor treatment. Main reasons for therapy initiation included cytoreduction and risk-reduction for both ET and MF (>40% of cases). Other reasons for MF treatment were splenomegaly and symptom control in 19.3% and 18.5% of the cases, respectively. In summary, more than 40% of patients classified as ET did not receive histopathological BM assessment at diagnosis while the majority met minor criteria of primary myelofibrosis. Conversely, more than 60% of patients categorized as MF did not receive early prognostic risk-assessment. We conclude that improved histopathologic diagnostics and stringent use of the WHO criteria for cases of suspected ET and MF are necessary for proper risk assessment and therapeutic stratification.

Schmidt:Novartis: Research Funding. Bernhardt:Novartis: Research Funding. Fries:Novartis: Research Funding. Jentsch-Ulrich:Novartis: Research Funding. Josting:Novartis: Research Funding. Kreher:Novartis: Research Funding. Steinmetz:Novartis: Research Funding. Tesch:Novartis: Research Funding. Kaufmann:Novartis: Current Employment. Rager:Novartis: Current Employment. Crodel:Novartis: Consultancy, Honoraria; BMS: Honoraria; AstraZeneca: Honoraria. Palandri:Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Sobi: Consultancy, Honoraria; CTI: Consultancy, Honoraria; Kartos/Telios: Consultancy, Honoraria; AOP: Consultancy, Honoraria; Sierra Oncology: Consultancy, Honoraria. Heidel:Celgene/BMS: Consultancy, Research Funding; CTI: Consultancy, Research Funding; AOP: Consultancy; Novartis: Consultancy, Research Funding.