Limited efficacy of Venetoclax Combination Regimens in Acute Myeloid Leukemia with Extramedullary Relapse.

The recently approved Bcl-2 inhibitor venetoclax (VEN) has achieved promising outcomes in new and relapsed/refractory (R/R) acute myeloid leukemia (AML). Although its use is not well-established in R/R AML with extramedullary disease (EMD), some reports have shown promising outcomes. We retrospectively analyzed 11 patients of R/R AML with EMD [with (n=4) or without (n=7) concurrent marrow involvement], who were treated with VEN plus decitabine (n=9) or low-dose cytarabine (n=2) between May 2020 and October 2020 in Seoul St. Mary's Hospital. The median number of prior treatment lines was 3 (1-6) and most (n=9, 81.8%) had multiple sites of EMD. Nine patients (81.8%) received concurrent therapy for EM involvement sites with radiotherapy (RT) (n=4), surgery (n=1) and both of them (n=4). Among 11 patients, four patients (36.4%) had either marrow or EM responses to VEN-combination; EM response was seen in one patient (9.1%, partial response) who had received concurrent radiotherapy (25Gy, 10fx) during 1st cycle of VEN-combination, and other three patients showed marrow response without EM response. After median follow-up of 27.0 months, the median overall survival was estimated to be 5.4 months. To conclude, VEN-combination regimens have shown only modest efficacy in EM recurrence of AML with little impact on eliciting EM response.