OPB-111077

OPB-111077 is a novel inhibitor of STAT3 and mitochondrial oxidative phosphorylation that exhibited promising anticancer activity in preclinical models. In this first-in-human phase I study of OPB-111077 in unselected advanced cancers, treatment-emergent adverse events, most frequently nausea, fatigue, and vomiting, were generally mild to moderate in intensity and could be medically managed. Overall, only modest clinical activity was observed after OPB-111077 given as monotherapy. Notable antitumor activity was seen in a subject with diffuse large B-cell lymphoma.

OPB-111077 is a novel inhibitor of STAT3 and mitochondrial oxidative phosphorylation with promising anticancer activity in preclinical models.

Open-label, phase I trial of OPB-111077 in advanced cancers with no available therapy of documented benefit. Initial dose escalation in unselected subjects was followed by dose expansion. Patients received oral OPB-111077 daily in 28-day cycles until loss of clinical benefit.

Eighteen subjects enrolled in dose escalation, and 127 in dose expansion. Dose-limiting toxicities were observed at 300 mg and 400 mg QD; maximum tolerated dose was defined as 250 mg QD. Frequently reported treatment-emergent adverse events (TEAEs) included nausea, fatigue, and vomiting. TEAEs were generally mild to moderate and could be medically managed. OPB-111077 reached micromolar drug concentrations, had an elimination half-life of approximately 1 day, and reached steady-state by day 8. A durable partial response was observed in one subject with diffuse large B-cell lymphoma. Seven subjects with diverse tumor types had stable disease or minor responses for at least eight treatment cycles (224 days).

OPB-111077 is generally well tolerated, and its pharmacokinetic profile is sufficient for further clinical development. Notable clinical activity was observed in a subject with diffuse large B-cell lymphoma. Overall, modest efficacy was observed against unselected tumors.

OPB-111077 is a novel, highly specific oral signal transducer and activator of transcription 3 inhibitor that has exhibited good efficacy against solid and blood cancers, including acute myeloid leukemia (AML), in preclinical models. In the present study, a phase 1b, two-stage, 3+3 dose-escalation clinical trial [dose level (DL)1 of 200 mg/day and DL2 of 250 mg/day on a once daily dose schedule in 28-day cycles] was conducted to assess the maximum tolerated dose (MTD), safety profile and the preliminary antitumor activity of OPB-111077 in patients with high-risk AML. A preliminary preclinical analysis evaluated the anti-proliferative activity of OPB-111077 in 19 patients with AML with a Vivia Biotech ex vivo PharmaFlow precision medicine test. A total of 12 patients were ultimately enrolled in the trial: 5 patients (42%) were treated with DL1, and 7 (58%) were escalated to DL2 of OPB-111077. Dose-limiting toxicities were not observed and the MTD was not reached. In addition, the most frequently reported treatment-emergent adverse events were nausea, vomiting and fatigue. Finally, clinical activity (overall response) was observed in 3 patients (25%). On the whole, the present study demonstrates that OPB-111077 exhibits a good safety and tolerability profile and an acceptable clinical response in patients with high-risk AML. A biomarker-driven design is useful for selecting the study population upfront.