Glasdegib is a potent and selective oral inhibitor of the Hedgehog pathway. We report data from the single-arm, lead-in cohort of an open-label phase 1b/2 trial of glasdegib in patients with primary/secondary myelofibrosis (MF) previously treated with at least one Janus kinase inhibitor (JAKi). Patients received glasdegib 100 mg orally once daily until there was no further clinical benefit. Primary endpoints included adverse events (AEs). Secondary endpoints included patients with spleen volume reduction (SVR) ≥35% at week 24, patients with ≥50% total symptom score (TSS) reduction, and pharmacokinetics. All 21 treated patients had one or more AE and five (23.8%) had serious AEs. Most common (>30%) AEs were dysgeusia (61.9%), muscle spasms (57.1%), alopecia (38.1%), fatigue (33.3%), and decreased appetite (33.3%). Although no patient had ≥35% SVR at week 24, one patient previously treated with ruxolitinib had an SVR of 32.9%. At week 12, two (9.5%) patients had ≥50% reduction in TSS from baseline and ˜40% had ≥20% reduction. One patient had an anaemia response. Following administration of glasdegib 100 mg once daily, the median time to peak plasma concentrations at steady-state generally occurred at 1 h post-dose. The safety profile of glasdegib monotherapy was manageable in patients with primary/secondary MF. Further study of glasdegib in combination with JAKi in a MF population may be warranted.

This is the primary report of the randomized, placebo-controlled phase 3 BRIGHT AML 1019 clinical trial of glasdegib in combination with intensive chemotherapy (cytarabine and daunorubicin) or non-intensive chemotherapy (azacitidine) in patients with untreated acute myeloid leukemia. Overall survival (primary endpoint) was similar between the glasdegib and placebo arms in the intensive (n = 404; hazard ratio [HR] 1.05; 95% confidence interval [CI]: 0.782-1.408; two-sided p = 0.749) and non-intensive (n = 325; HR 0.99; 95% CI: 0.768-1.289; two-sided p = 0.969) studies. The proportion of patients who experienced treatment-emergent adverse events was similar for glasdegib versus placebo (intensive: 99.0% vs. 98.5%; non-intensive: 99.4% vs. 98.8%). The most common treatment-emergent adverse events were nausea, febrile neutropenia, and anemia in the intensive study and anemia, constipation, and nausea in the non-intensive study. The addition of glasdegib to either cytarabine and daunorubicin or azacitidine did not significantly improve overall survival and the primary efficacy endpoint for the BRIGHT AML 1019 phase 3 trial was not met. Clinical trial registration: ClinicalTrials.gov: NCT03416179.