PracticeUpdate: Oncology - Winter 2018

EHA 2018 33

EUTOS Long-TermSurvival Score Superior for Prognosis of Survival in CML Sokal score allocated more patients to high-risk group than the ELTS T he EUTOS long-term survival score (ELTS) is recommended to predict long-term survival in patients with chronic-phase (CP) chronic myeloid leukaemia (CML). high but ELTS non-high-risk patients (6-year OS: 88%. CI 85–91%) showed higher OS than the 526 common high-risk patients (P = .0036, 6-year OS: 81%, CI 76–85%). Of the 3,037 patients identi- fied as low risk by the ELTS score, the Sokal score allocated 1,200 (40%) to non-low-risk groups.

The ELTS was originally developed to distinguish three groups of patients with different probabilities of dying from CML in a cohort of 2,205 imatinib-treated patients who were part of the European Treatment and Outcome Study (EUTOS) registry. The registry con- tains data on adult patients with CP CML. Many investigators, however, continue to rely on the Sokal score for the prognostic discrimination of CML patients treated with tyrosine kinase inhib- itors (TKIs). Of the original cohort, the Sokal score had allocated 23% of patients to the high-risk group, the ELTS score only 12%. In their abstract, the research team, led by Markus Pfirrmann, MsC, a senior scientist, biometrician, and epidemiologist with the Ludwig Max- imilian University of Munich, Germany, stated that the long-term outcome of TKIs suggests that allocating >20% CP CML patients into a high-risk group is “too pessimistic.” Due to the success of TKIs, the number of deaths from CML has declined considerably. The current study compared risk group allocations and prognoses between the two scoring systems. The researchers found that the Sokal score allocated 13% (n=671) more patients to the high-risk group than the ELTS score. As these patients had significantly and clinically relevant lower cumulative incidence probabilities (CIPs) of death and higher overall survival (OS) probabilities, the allocation of the Sokal score was not appropriate, they concluded. For this study, an additional 2,949 patients from other registry sections were included in the review, and survival was calculated from the date of start of treatment to death. The CIPs of dying of CML were compared with the Gray test and OS probabilities with the log-rank test. Only death after confirmed disease progression was regarded as death due to CML. The 5,154 patients in the combined registry had a median obser- vation time of 5.3 years. Six-year OS probability was 90% (95% CI 89–91%). Of 429 deceased patients, in 175 CML progression prior to death was confirmed (40%). The 6-year CIP of dying of CML was 4% (95% CI 4–5%). From low- to high-risk groups, the Sokal score resulted in 6-year CIPs of 3% (n=1,982 [38% of 5,154], CI 2–3%), 4% (n=1,975 [38%], CI 3–5%), and 8% (n=1,197 [23%], CI 6–10%). This compared to the ELTS score in 6-year CIPs of 2% (n=3,037 [59%], CI 2–3%), 5% (n=1,449 [28%], CI 4–7%), and 12% (n=668 [13%], CI 9–1 5%). Of the 1,197 patients allocated as high risk by the Sokal score, the ELTS score classified 671 (56%) as non-high risk. Compared to the 526 high-risk patients according to both scores (6-year CIP of dying: 12%, CI 9–16%), the CIPs of dying were lower for the non- high risk patients (P = .0003, 6-year CIP: 5%, CI 3–7%). The Sokal " From low- to high-risk groups, the Sokal score resulted in 6-year CIPs of 3% and 8%. This compared to the ELTS score in 6-year CIPs of 2%, 5%, and 12%. "

The researchers found that without significant CIP differences to the latter group, at 6 years, the CIP of dying was 2% (CI 1–3%) in the 1,837 low-risk and 2% in the 1,200 non-low-risk patients (CI 2–4%). OS of the Sokal non-low-risk patients (6-year OS: 92%. CI 90–94%) was lower than in the cases classified as low-risk by both scores (6-year OS: 95%. CI 94–96%, P = .0186). Overall survival probabilities but not the CIPs of 1,200 patients assessed as low-risk by the ELTS and non-low-risk by the Sokal score were different from the probabilities of 1,837 assessed as low-risk patients by both scores, the researchers stated. For the prediction of long-term survival, they recommended the use of the ELTS score. www.practiceupdate.com/c/69757

© EHA 2018

VOL. 2 • NO. 3 • 2018