An open-label Phase 1b study to investigate the preliminary safety and activity of aldoxorubicin plus gemcitabine in subjects with metastatic solid tumors administered at doses of 170, 250 or 350 mg/m2 by intravenous infusion (IVI) on Day 1 every 21 days plus 900 mg/m2 gemcitabine on Days 1 and 8 every 21 days.