Lymphocytosis, which occurred and persisted in many dasatinib-treated patients in all phases of chronic myeloid leukemia (CML), is associated with higher response rates, significantly longer response durations, and improved overall survival, a study published in the journal Cancer has shown.1

Because the proliferation of clonal cytotoxic T-cells or natural killer cells has been observed following treatment with dasatinib in small studies of patients with CML, researchers sought to evaluate the incidence of lymphocytosis and its association with response, survival, and side effects in these patients.

For the study, researchers analyzed data from 1402 dasatinib-treated patients with newly diagnosed CML in chronic phase (CML-CP), CML-CP refractory or intolerant to imatinib, or with CML in accelerated or myeloid-blast phase. Patients were participants in 3 large clinical trials.

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Researchers found that 32% to 35% of patients developed lymphocytosis, which persisted for more than 12 months. Of note, this persistence of lymphocytosis was not observed in patients treated with imatinib.

Results showed that patients who received dasatinib in all stages of CML and developed lymphocytosis were more likely to achieve a complete cytogenetic response. Further, patients with CML-CP and lymphocytosis had an increased likelihood of achieving major and deep molecular responses.

Investigators also observed significantly improved progression-free and overall survival rates in patients with CML-CP who were refractory to or intolerant of imatinib and had lymphocytosis.

In terms of its association with adverse events, pleural effusions were more frequently reported in patients with lymphocytosis.

“Prospective studies are warranted to characterize the functional activity of these cells and to assess whether an immunologic effect against CML is detectable,” the researchers conclude.


1. Schiffer CA, Cortes JE, Hochhaus A, et al. Lymphocytosis after treatment with dasatinib in chronic myeloid leukemia: effects on response and toxicity [published online ahead of print March 21, 2016]. Cancer. doi:10.1002/cncr.29933.