Clinical features of dasatinib-induced large granular lymphocytosis and pleural effusion.

During follow-up of leukocyte counts in 20 consecutive patients (age range 29-81 years) treated with dasatinib, 9 patients (7 chronic myeloid leukemia in chronic phase, 2 Philadelphia chromosome-positive acute lymphoid leukemia in complete remission) developed lymphocytosis (>3,000/microl). Peripheral blood smears revealed a population of large granular lymphocytes. Large granular lymphocytosis (LGL) was first noted between 1 and 8 months after initiation of dasatinib, and it has persisted up to 33 months from the onset of LGL in one patient. Peak numbers of large granular lymphocytes ranged from 2,915 to 17,425/microl. The occurrence of LGL might interfere with achieving molecular response (MR, real-time quantification of major BCR-ABL1 mRNA less than 50 copies/microg RNA) in our small cohort; 8 (89%) of 9 patients with LGL attained MR, while only 6 (55%) of 11 patients without LGL eventually achieved MR. With respect to the relationship between LGL and pleural effusion (PE), 3 (27%) of 11 patients without LGL developed PE, while 5 (56%) of 9 patients with LGL developed PE. Moreover, the mean peak number of LGL was 9,215/microl, which was much higher than the mean peak number (4,635/microl) of LGL in patients without PE. These results may suggest possible association of both events in our cohorts.