Design of preparative regimens for stem cell transplantation in breast cancer

We have evaluated tandem cycles of a tri-drug combination, termed CVP (cyclophosphamide, etoposide [VP-16], and cisplatin [Platinol]), at four levels in more than 300 patients with various types of tumors. Tandem CVP appears to be at least therapeutically equivalent to alternatives. A second potentially noncross-resistant combination of mitoxantrone and thiotepa (MT), with or without etoposide, has been used in sequence following CVP to improve long-term, disease-free survival in patients who have multiple metastatic sites, who relapse shortly after adjuvant therapy, or who show other unfavorable clinical features. A combination of MT and etoposide (MVT) achieved an overall response rate of 61% in 32 patients with metastatic or refractory breast cancer. The etoposide was then eliminated to decrease the major toxicities of this regimen. MT was subsequently given to 37 evaluable patients prior to bone marrow infusion. The overall response rate was 48.5%. Thirty patients with metastatic breast cancer were then treated with induction therapy, a cycle of CVP, and then a cycle of MT. Given the low complete remission (CR) rate to induction therapy in these patients, the CR rate achieved with CVP-MT was encouraging. Further studies are ongoing.