A Phase I dose escalation trial of continuous infusion paclitaxel to augment high dose cyclophosphamide and thiotepa plus stem cell rescue for the treatment of patients with advanced breast carcinoma

BACKGROUND: Paclitaxel, an effective chemotherapeutic agent in the management of breast carcinoma, may have activity in women whose disease has recurred after high dose chemotherapy. With this is mind the authors explored the addition of a 120-hour continuous infusion of paclitaxel to a previously reported regimen comprised of high dose cyclophosphamide and thiotepa. METHODS: Thirty-one women with advanced breast carcinoma (30 patients with Stage IV disease and 1 patient with Stage IIIB disease) underwent harvest and cryopreservation of bone marrow and/or peripheral blood progenitor cells. High dose cyclophosphamide (2.5 g/m2) and thiotepa (225 mg/m2) were administered intravenously on Days -7, -5, and -3. Paclitaxel was administered as a 120-hour continuous infusion starting on Day -7. RESULTS: Three patients were treated at the initial cohort dose of 50 mg/m2 (over 120 hours), 6 patients at 100 mg/m2, 6 patients at 125 mg/m2, 6 patients at 150 mg/m2, 6 patients at 180 mg/m2, and 4 patients at 210 mg/m2. All patients completed the treatment protocol as planned with no associated transplant-related deaths. Mucositis as evidenced by either stomatitis or noninfectious diarrhea was experienced by all patients and was determined to be the dose-limiting toxicity at the 210 mg/m2 dose level. One patient with dose-limiting mucositis required intubation for airway protection and also experienced Grade 3 (according to the Cancer and Leukemia Group B common toxicity grading scale) pulmonary and neurologic toxicity. Only one Grade 3 toxicity was encountered below the maximum tolerated dose in a patient who developed diffuse alveolar hemorrhage at a dose of 125 mg/m2. No allergic reactions or clinical evidence of peripheral neuropathies were encountered. Cardiac, hepatic, and renal toxicities were minimal. Response rates in this previously treated patient population were difficult to assess in light of the high incidence of bone metastases; an overall response rate of 24% was obtained. CONCLUSIONS: Paclitaxel at a dose of 180 mg/m2 as a 120-hour continuous infusion may be added safely to high dose cyclophosphamide and thiotepa with autologous stem cell rescue. Further studies are ongoing to evaluate the efficacy and further define the toxicity of this recommended Phase II dose.