Hematologic effects of interleukin-1 beta, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor in tumor-bearing mice treated with fluorouracil.

Myelosuppression following intensive chemotherapy in cancer patients is associated with increased morbidity and mortality. Hematopoietic growth factors such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), alone or in combination with interleukin-1 (IL-1), have been shown to counteract myelosuppression resulting from some, but not all, chemotherapeutic regimens. In an attempt to apply these findings to intensive therapy with proliferation-dependent chemotherapeutic drugs such as fluorouracil (5-FU), we investigated combination biochemotherapy in a murine model. Female CD8F1 [(BALB/c X DBA/8)F1] mice bearing first-passage transplants of spontaneous CD8F1 breast tumors were treated intraperitoneally once a week for 3 successive weeks with a course of 5-FU alone or with a course of 5-FU in combination with recombinant human interleukin-1 beta (rHuIL-1 beta) alone or in combination with CSFs. rHuIL-1 beta alone or in combination with rHuG-CSF or recombinant murine GM-CSF significantly improved tumor growth inhibition (60% vs. 90%) and survival (20% vs. 90%-100%), increased the maximally tolerated dose of 5-FU, accelerated recovery of neutrophil counts in peripheral blood, and reduced duration of significant neutropenia and loss of body weight (29% vs. 10% loss). Clinical trials of IL-1 have been initiated in patients with advanced cancer receiving multiple courses of high-dose 5-FU.