As of April 15, 2024, 39 patients (median age, 74 years) with a median of 2 prior lines of therapy (range: 1-5) were treated with DFV890 in the dose-optimization part. Based on an 8-week screening period, 8 patients (20.5%) were RBC transfusion independent at baseline. Eighteen patients received low dose (17 with LR-MDS; 1 with LR-CMML), and 21 patients received high dose (18 with LR-MDS; 3 with LR-CMML). At data cutoff, 10 (25.6%) patients had discontinued treatment. Median duration of exposure was 10.7 weeks (range, 0.6-42.0 weeks). Adverse events (AEs) leading to study drug discontinuation were only reported in the high dose arm (2 patients, grade ≥3 neutropenia, n=1 and blood bilirubin increased, n=1). Treatment-related AEs (TRAEs) were reported in 10 patients (25.6%), with 4 (10.3%) experiencing grade ≥3 TRAEs (anemia [n=2], neutropenia, and rash [n=1 each]). No serious AEs related to DFV890 were reported. Peripheral cytokines were assessed as a marker of preliminary activity. Decrease in plasma IL-18 and IL-1RA levels observed in most patients, with a higher frequency in the low dose arm (IL-18 decreased in 8/8 patients in low dose arm vs. 4/7 in high dose arm; IL-1RA in 7/8 vs. 5/7), potentially due to less frequent dose interruptions. Changes in serum IL-6 levels were more heterogeneous; notably, among the patients with complete mutation and biomarker data, both patients with mutations in TET2 showed dramatic decreases in serum IL-6; IL-18 and IL-1RA also decreased in those patients. In addition, out of 8 patients who were transfusion-independent at baseline, 6 reported an increase in hemoglobin with treatment, 4 of whom with an increment >10% from baseline. Updated data including hematologic response assessment according to IWG will be presented at the meeting.
