Treatment patterns and clinical outcomes of tyrosine kinase inhibitors in chronic‐phase CML in clinical practice: 3‐year European SIMPLICITY data

OBJECTIVES: SIMPLICITY (NCT01244750) is an observational study of patients with chronic‐phase chronic myeloid leukemia (CP‐CML) in routine clinical practice receiving first‐line tyrosine kinase inhibitors (TKIs). We evaluated TKI treatment changes and how switching affects clinical response in patients recruited in Europe with ≥3 years of follow‐up. METHODS: The SIMPLICITY European cohort (France, Germany, Italy, the Netherlands, Russia, and Spain) included 431 patients. 370 (86%) were followed for ≥3 years. RESULTS: Proportions of patients experiencing treatment interruptions, TKI switching, and discontinuations decreased over 3 years’ follow‐up. Intolerance was a key driver for treatment changes. Complete cytogenetic response (CCyR) was achieved in 87.5% of patients switching TKI within 3 years of initiation vs 91.7% of non‐switchers. Major molecular response (MMR) was achieved in 82.4% of switchers vs 92.9% of non‐switchers. Over 3 years, not switching TKI was a strong predictor for achieving CCyR or MMR (both P < .05). Three‐year survival remained high, irrespective of treatment changes (95.3% switchers, 96.4% non‐switchers). CONCLUSIONS: European patients with CP‐CML who do not switch TKI are more likely to achieve clinical response, while intolerance is a key driver for switching. Successful CML management may require careful selection of initial TKI, with early monitoring of response and intolerance.