Rapid administration of multiple cycles of high-dose myelosuppressive chemotherapy in patients with metastatic breast cancer.

PURPOSE

To determine the feasibility and safety of a rapidly cycled sequence of high-dose myelosuppressive chemotherapy courses.

PATIENTS AND METHODS

Seventeen patients with metastatic breast cancer were treated with two courses of cyclophosphamide (CPA; 3.0 g/m2) supported by granulocyte colony-stimulating factor (G-CSF). Following the first CPA treatment, peripheral-blood leukaphereses commenced when the leukocyte count recovered to 1.0 x 10(9)/L. After hematologic recovery from the second dose of CPA, patients were treated with carboplatin 1,500 mg/m2, etoposide 1,200 mg/m2, and CPA 5.0 g/m2 administered over 3 days. The peripheral-blood progenitors (PBPs) were reinfused 3 days later, and G-CSF was recommenced.

RESULTS

All patients received the three courses. The median interval between treatments was 14 days (range, 13 to 21). Sixteen of the 34 courses of CPA resulted in admissions for fever. Following the third course, neutrophil counts recovered to 0.5 x 10(9)/L at a median of 9 days (range, 8 to 18) after PBP reinfusion and platelets recovered to 50 x 10(9)/L at a median of 12 days (range, 9 to 102). There were no treatment-related deaths. Flow-cytometric analysis was performed on the leukapheresis collections of eight patients. Seven patients with at least 2.0 x 10(6) CD34+ CD33- cells per kilogram body weight exhibited prompt hematologic recovery. One patient with 0.03 x 10(6) CD34+ CD33- cells was still cytopenic on day 21, and required reinfusion of her back-up marrow. Among seven patients with measurable or assessable disease, there were two complete responses (CRs) and four partial responses (PRs).

CONCLUSION

These preliminary results suggest that multiple, rapidly cycled courses of high-dose myelosuppressive chemotherapy can be administered. PBPs, harvested during the G-CSF-augmented rebound from CPA-induced cytopenia, produce rapid hematologic recovery in patients undergoing high-dose chemotherapy (HDC). Further follow-up will be necessary to assess the efficacy of this specific regimen in the treatment of metastatic breast cancer.