A phase Ib study of cancer stem cell (CSC) pathway inhibitor BBI-608 in combination with gemcitabine and nab-paclitaxel (nab-PTX) in patients (pts) with metastatic pancreatic ductal adenocarcinoma (mPDAC).

284 Background: BBI-608 is an oral first-in-class cancer stemness inhibitor that works by blocking STAT3-mediated transcription of cancer stemness genes. Potent anti-CSC activity was observed in vitro and in vivo, in mono- and combination therapy. In phase I studies, BBI-608 was generally well tolerated with encouraging signs of anti-tumor activity. Methods: A phase Ib open label, multi-center study in pts with mPDAC was performed to determine RP2D, safety, tolerability, and preliminary anti-cancer activity of BBI-608 in combination with Gemcitabine and nab-PTX. BBI-608 was administered at 240 mg BID in combination with Gemcitabine 125 mg/m2 and nab-PTX 1000 mg/m2administered weekly for 3 out every 4 weeks until progression of disease, unacceptable toxicity, or other discontinuation criterion was met. Results: 31 pts were enrolled and received BBI-608 in combination with Gemcitabine and nab-PTX for a total sum of 83 study cycles. 25 of 31 pts (80.6%) were treatment-naive and 6 pts (19.4%) received 1 prior...