Ibandronate reduces osteolytic lesions but not tumor burden in a murine model of myeloma bone disease

We determined the effects of the potent bisphosphonate ibandronate in a mur ine model of human myeloma bone disease. In this model, bone lesions typica l of the human disease develop in mice following inoculation of myeloma cel ls via the tail vein. Treatment with ibandronate (4 mu g per mouse per day) significantly reduced the occurrence of osteolytic bone lesions in myeloma -bearing mice. However, ibandronate did not prevent the mice from developin g hindlimb paralysis and did not produce a detectable effect onsurvival. Th ere was no significant effect of ibandronate on total myeloma cell burden, as assessed by morphometric measurements of myeloma cells in the bone marro w, liver, and spleen, or by measurement of serum IgG2b levels. These result s support clinical findings that bisphosphonates may be useful for the trea tment of myeloma-associated bone destruction, but suggest that other therap ies are also required to reduce tumor growth. (C) 1999 by The American Soci ety of Hematology.