Effect of early blood counts on overall survival (OS) following glasdegib + LDAC in newly diagnosed AML: BRIGHT AML 1003 post hoc analysis

7525 Background: Addition of glasdegib (GLAS) to LDAC approximately doubled OS without significant worsening of myelosuppression-related complications, ostensibly by targeting leukemic stem cells dependent on the hedgehog pathway, which is not involved in normal adult hematopoiesis. We assessed potential association of early blood counts and OS. Methods: In BRIGHT AML 1003, patients (pts) with newly diagnosed AML were randomized to GLAS + LDAC (n = 78) or LDAC alone (n = 38). GLAS was given once daily continuously and LDAC on days 1–10 of a 28-day cycle. We evaluated peripheral blood counts measured early in the study (cycle 2 day 1 [C2D1]), approximately 1 month before the first bone marrow assessments. OS was compared for GLAS+LDAC vs LDAC alone subgroups meeting thresholds of absolute neutrophil count (ANC; ≥1000 or 500/µL), hemoglobin (Hb; ≥10 or 9 g/dL) or platelets (≥100,000 or 50,000/µL). Data cut-off was Apr 2019. Results: Among all pts regardless of baseline values, achievement of ANC, Hb and platelet thresholds at C2D1 was associated with improved OS with GLAS+LDAC (table, left side). Notably, in pts who did not meet ANC, Hb or platelet thresholds (table, right side), OS benefit with GLAS+LDAC was also observed (table, all p≤0.05). Among pts below threshold at baseline, C2D1 recovery of platelets ≥50,000 or 100,000 and Hb ≥9 or 10 was associated with improved OS (not shown). Clinical trial information: NCT01546038 . Conclusions: In pts with newly diagnosed AML, improved OS was associated with various blood count thresholds after 1 cycle of GLAS+LDAC vs LDAC alone. In pts with baseline measurements below threshold, recovery of specific thresholds was associated with improved OS. These exploratory results are consistent with the hematopoiesis-sparing mechanism of GLAS, and merit further evaluation. [Table: see text]