Eligible patients will receive continuous metronomic oral cyclophosphamide at a dose of 50mg daily. Tumor assessments will be performed at baseline and every 6 weeks thereafter to assess response and disease progression. Toxicity will be monitored throughout treatment. The study's primary end point is defined as clinical benefit rate (CBR) at 12 weeks as a measure of disease control. The study is designed to distinguish a favorable true PFR of 40% from a null rate of 20% [Van Glabbeke et al. EJC 2002]. With a CBR of 40%, metronomic oral cyclophosphamide at this dose and schedule in this patient population will be considered worthy of further evaluation.