PB1947 COMPARISON OF EFFICACY AND SIDE EFFECTS OF SECONDLINE DASATINIB AND NILOTINIB THERAPIES IN PATIENTS WITH CHRONIC MYELOID LEUKEMIA IN CHRONIC PHASE RESISTANT OR INTOLERANT TO IMATINIB

Background: Twenty to 30% of imatinib‐treated CML patients in the chronic phase of the disease may necessitate a switch to second‐line therapies due to toxicity or lack of efficacy. In clinical trials, nilotinib and dasatinib have been shown to be effective and safe in second‐line treatment in these patients. There is no clinical study comparing the efficacy and side‐effect profile of nilotinib and dasatinib in second‐line treatment. Real life data on this subject is also limited. Aims: The aim of this study was to compare the efficacy and side effects of two tyrosine kinase inhibitors in patients with chronic myeloid leukemia in chronic phase (CML‐CP) who are resistant or Intolerant to Imatinib. Methods: We retrospectively analyzed a database of consecutive CML‐CP patients treated with either nilotinib or dasatinib in the second line at our hematology outpatient clinic between January 2003 and July 2018. Results: Forty‐one patients received dasatinib and 36 patients received nilotinib treatment. Median follow‐up period was 30.0 months in both groups. The rate of ≥ major molecular response was 100% in patients receiving nilotinib treatment and 87.5% in patients receiving dasatinib. However, the difference was not statistically significant. Treatment discontinuation was more frequent in patients receiving dasatinib than in nilotinib group (20 (48.8%) patients in dasatinib, 13 (36.1%) patients in the nilotinib group respectively p = 0.11). The reasons for discontinuation of treatment were loss of response (13%), hematological toxicity (2%), non‐hematological toxicity (19%) in nilotinib group and progression (2%), lack of achievement of response (7%), loss of response (4%), hematological toxicity (4%), non‐hematological toxicity (24%) in dasatinib group. The most common side effects were skin rash (11%) in nilotinib treated patients and pleural effusion (26%) in the dasatinib group. Treatment failure was detected in 5 (13%) patients with nilotinib and 8 (19.5%) patients with dasatinib (p = 0.11). Overall, 2 patients (5%) from the second‐line nilotinib treatment group had died at the time of analysis. One patient died of a cause not related to the disease, and one patient died of grade 4 pancreatitis. One patient (2%) had died in the dasatinib group because of a cause not related to the disease. The median event‐free survival was 63 months in patients receiving nilotinib and 75 months in patients receiving dasatinib. The difference was not statistically significant (p = 0,35). Median OS was not reached in both groups. Summary/Conclusion: As shown in clinical studies, nilotinib and dasatinib were found to be highly effective and safe in the second line treatment of CML‐CP with high response rates in our daily routine hematology practice. In our patient group, it was determined that both drugs showed similar activity. There is a need for larger studies involving more patients to achieve real‐life data.