BBI608-201GBM: A phase Ib/II clinical study of napabucasin (BBI608) in combination with temozolomide (TMZ) for adult patients with recurrent glioblastoma (GBM).

Abstract

e13525 Background: Napabucasin, a first-in-class cancer stemness inhibitor in clinical development, suppresses cancer stemness by targeting STAT3-driven gene transcription. Pre-clinically, potent and broad-spectrum anti-cancer activity was observed in vitro and in vivo, alone and in combination with other agents. PK studies demonstrated napabucasin penetration in the murine orthotopic GBM model. Methods: A phase Ib/II open-label, multi-center study in pts with GBM at first recurrence who have not received bevacizumab, was performed to determine safety and preliminary activity of napabucasin administered orally at 480mg BID po in combination with TMZ 150mg/m²/day po; days 1 through 5 of each 28 day cycle, until disease progression or unacceptable toxicity. A 6-patient safety cohort was planned to evaluate the occurrence of DLT during the first 28 days of combination treatment with napabucasin and TMZ. 4 additional patients have been enrolled under the RP2D expansion phase. Results: 11 pts have been enrolled to date; no DLT was observed in the safety cohort and the RP2D of the combination is 480 mg BID for napabucasin. The safety profile was consistent with that of each agent as monotherapy and most common AEs included grade 1/2 diarrhea, nausea, abdominal cramps, and vomiting. Two patients requested to withdraw treatment due to concurrent conditions and AE s. 9 patients were evaluable by RANO; Disease Control Rate was observed in 5 patients (55.5%) of which 4 achieved PR (44.4%) and 1 achieved SD (11.1%). The Overall response rate was 44.4% in the evaluable patients. Conclusions: This phase Ib/II study demonstrated that napabucasin at 480 mg BID can be safely combined with temozolomide at full dose and showed encouraging anti-tumor activity in patients with recurrent Glioblastoma. Clinical trial information: NCT02315534. [Table: see text]