A phase Ib, single-centre, dose-escalation trial with a traditional escalation rule with fixed dose levels ("3 + 3" rule). The recommended phase II dose will be defined as the maximum predefined dose level at which 0 of 3 or ≤ 1 of 6 subjects experience a drug-related dose limiting toxicity (DLT) during cycle 1 and 2 of treatment. An estimated 10-20 patients will be required for this study.