Context

EUTOS score is the prognostic score validated in the TKI era. This score can be influenced by many factors, especially in developing countries, like parasitic infestations, viral infections and allergic reactions. Refinement of this score is a need with the emergence of more potent TKIs and for better recognition of high-risk patients.

Objective
The main objective of this study is to see whether the replacement of the basophil percentage with serum tryptase as a marker of basophil cell mass may change the predictive power of this score.

Design
This observational study included newly diagnosed CML patients in the period from October 2016 to April 2017. Those patients were followed up till the reporting date in April 2019.

Setting
Patients were recruited from the Alexandria university hospital as a terminal referral center.

Patients
The 48 included patients were newly diagnosed chronic phase CML patients excluding accelerated phase and blastic crisis. The female to male ratio was 1:1 with the mean age at presentation 43.94 years. Nineteen age and sex match individuals were included as a control group for tryptase. Patients who completed the follow up were 100% and 2 patients died during the follow up.

Interventions
Serum tryptase was measured for patients and controls using quantitative sandwich ELISA technique (EIAab kit catalog no: E1070h, China). Then the prognostic scores Sokal, Hasford and EUTOS were calculated adding to this the proposed score EUTOS-T replacing the basophil percentage with the serum tryptase. The follow up was done at 3-month intervals measuring the BCR/ABL-1 transcripts and the results were correlated to the baseline scores.

Results
The results showed that EUTOS score had lower sensitivity and specificity of defining the high-risk group at the cut-off value of 87 suggesting the higher splenic measurements and basophilia in the studied group; however this score showed better sensitivity and specificity (86.67% and 84.85% respectively) at a cut-off value of 154. EUTOS-T score showed higher sensitivity of 93.33% and a negative predictive value of 95.7%. Besides, the correlation between the molecular failure at 12 months was the strongest with EUTOS-T giving p-value <0.001.

Conclusion
Using EUTOS-T score resulted in better prediction of molecular progression and shorter overall survival of high-risk patients that leads to better choice of the frontline treatment regimens.

Keywords
CML, chronic myelogenous leukemia, tryptase, EUTOS, prediction, TKI