Cancer treatment interferes with bone development

According to researchers in the U.S. the cancer drug Gleevec (imatinib), which has dramatically improved survival prospects for some cancer patients, can interfere with bone development.

Gleevec is the treatment of choice for patients with chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST).

Gleevec is considered to be a well tolerated drug, however, side effects do occur, including a variety of skin reactions in approximately 10% of patients, joint effusions, hypopigmentation, renal dysfunction, hepatic dysfunction, myelosuppression and anemia.

The researchers from the Memorial Sloan-Kettering Cancer Center in New York say that some patients taking Gleevec develop hypophosphatemia which inhibits bone formation and resorption, a process known as bone remodelling.

The study focused on altered bone and mineral metabolism in patients receiving Gleevec.

They researchers say the new finding was based on 16 patients with low mineral levels, and the full significance of the discovery has yet to be ascertained.

The side effect was detected by Dr. Ellin Berman and colleagues after some patients on the drug developed low levels of serum phosphate, a mineral important in bone formation.

Gleevec was approved 5 years ago and the drug has transformed life expectancy for people with chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors (GIST).

Five years of use shows patients taking Gleevec have a 90 percent survival rate.

The bone problem is mentioned as an infrequent side effect in prescription information, says drug company Novartis, but the results of the study in which this occurred were not clinically significant.

According to the researchers the results suggest that the effects of Gleevec are wide ranging and complex and the clinical implications other than replacement therapy are unclear.

The study is published in the current issue of the New England Journal of Medicine.