Background: Despite recent progress in modern chemotherapy, metastatic solid tumors still have a poor outcome. The delivery of increased dose intensities of cytotoxic agents could improve response rates. We assessed the feasibility and safety of a high-dose sequential chemotherapy program in chemotherapy-naive patients with solid tumors.
Patients and methods: Thirty patients (14 with carcinoma of unknown primary site, seven with metastatic breast cancer, six with small-cell lung cancer, and three with other diseases) were treated by an induction therapy regimen consisting of four cycles of high-dose chemotherapy with hematopoietic progenitor cell and growth factor support. Peripheral blood progenitor cells were collected by apheresis as the leukocyte counts recovered from the nadir induced by the first cycle of chemotherapy (doxorubicin 75 mg/m2, cyclophosphamide 6000 mg/m2). Patients then received two cycles of etoposide (800 mg/m2) and carboplatin (900 mg/m2) separated by one cycle of doxorubicin (75 mg/m2) and cyclophosphamide (3000 mg/m2). G-CSF (5 microg/kg/d) was given until engraftment. Cycles were scheduled to be delivered every three weeks.
Results: A total of 108 cycles of chemotherapy were administered. Six patients went off study before the end of the program (three because of progressive disease, three because of toxicity). After the first cycle, a median number of 10 x 10(6)/kg CD34+ cells (range 8-30) were collected. The median number of apheresis procedures was 1 (range 1-3). From cycle 2 to cycle 4, the median number of days when there was an absolute neutrophil count of less than 500/microl increased from three to five, and the median number of days when the platelet count was less than 25,000/microl increased from three to six. Episodes of febrile neutropenia occurred in 36%, 50% and 46% of cycles during cycles 2, 3 and 4, respectively. The median numbers of days between cycle 1 and cycle 2, cycle 2 and cycle 3, cycle 3 and cycle 4 were 24 (range 20-30), 22 (range 20-36) and 22 (range 18-35), respectively. There were no treatment-related deaths. Non-hematologic toxicity included severe (WHO grades 3 or 4) nausea/vomiting in 19 (18%) cycles, mucositis in 8 (7%) cycles and diarrhea in 7 (6%) cycles.
Conclusion: Support with hematopoietic progenitor cells and growth factors allows the timely administration of repetitive cycles of high-dose chemotherapy in chemotherapy-naive patients, resulting in a significant increase in dose intensity. Toxicity is noteworthy but manageable and does not compromise further therapy.