A PHASE-II STUDY OF MITOXANTRONE, ETOPOSIDE, AND THIOTEPA WITH AUTOLOGOUS MARROW SUPPORT FOR PATIENTS WITH RELAPSED BREAST-CANCER

To further improve the effect of high-dose chemotherapy in the treatment of locally advanced and metastatic breast cancer, we sought to develop a second active high-dose noncross-resistant regimen to use in tandem with our customary high-dose regimen of cyclophosphamide, etoposide, and cisplatin (CVP). We performed a phase II trial of high-dose mitoxantrone 30 mg/m2, etoposide 200 mg/m2 every 12 hours x 6, and thiotepa 250 mg/m2 x 3 days (MVT) in 31 patients with heavily pretreated metastatic breast cancer and one with locally advanced chemotherapy-refractory breast cancer. These patients were ineligible for high-dose CVP chemotherapy because of the amount of prior treatment and poor-response status. Of the 32 patients, 14 responded to cycle 1, did not experience any grade 4 toxicity, and received a second cycle of MVT. Overall, seven of 31 patients achieved a complete response (CR; 23%). Four of the 14, who were partial responders to the first cycle, achieved a CR after the second cycle. The overall response rate was 19 of 31 (61%) with an overall median freedom from progression of 4 to 5 months and an overall median survival of 9 months. Toxicity consisted primarily of mucositis (grade 3 or 4 in 69%). The results indicate that high-dose MVT produces significant activity, even in heavily pretreated patients. Administration of a second cycle of high-dose therapy with MVT increased the CR rate, and the morbidity and mortality from the second cycle were not greater than that for the first cycle. Because of the high incidence of grade 3 or 4 mucositis with this regimen, we are currently completing a follow-up study of high-dose mitoxantrone and thiotepa alone.