A phase I-II study of high-dose cyclophosphamide, thiotepa and escalating doses of mitoxantrone with autologous stem cell rescue in patients with refractory malignancies

Twenty-five patients with refractory solid tumors were treated with high-dose cyclophosphamide, thiotepa and mitoxantrone followed by autologous stem cell rescue in a phase I dose escalation study. The dose-limiting toxic effect was mucositis at 60 mg/m² of mitoxantrone in combination with cyclophosphamide and thiotepa. The early death rate due to toxic effects was 24%; all deaths were attributed to infections. Hematopoietic recovery was quite prolonged with median times to granulocyte (>500 x 10⁶/l) and platelet (>50 x 10⁹/l) recovery at 58 and 148 days, respectively. The overall response rate was 56%. The median time to progression was 14 weeks. Thus, this regimen has activity against refractory malignancies although early and prohibitive toxicity occurs when mitoxantrone is escalated in this setting.