SF3B1 in chronic lymphocytic leukemia.

To the Editor: Wang et al. (Dec. 29 issue)1 report that SF3B1 mutation is associated with a shorter time to initiation of treatment in patients with chronic lymphocytic leukemia. However, this result should be interpreted with caution. In the discovery cohort of 91 patients, 29 were classified as having stage 0 disease, 43 as having stage I, and 19 as having stage III–IV according to the Rai classification (ranging from 0 [low risk] to I or II [intermediate risk] to III or IV [high risk]). At the time of the sampling, 61 of the patients had not received chemotherapy, whereas 30 had prior exposure to chemotherapy. It should be noted that the SF3B1 mutations could be acquired during progression of the disease, as shown in a recent article in which the mutations appeared in two of three cases in the serial analysis during the clinical course.2 These findings suggest that a number of SF3B1 mutations were acquired after initiation of treatment in the present study. Clinicians need information on whether SF3B1 mutation in patients who have not received chemotherapy is predictive of the time to initiation of treatment. Would the authors provide us with the data limited to the population in the discovery cohort?