Glivec (imatinib), which has dramatically improved survival prospects for some cancer patients, can interfere with bone development, according to U.S. researchers.

Results of a study published this week in The New England Journal of Medicine indicated that the drug inhibits bone formation and resorption - a process known as bone remodelling.

Novartis has not found similar adverse effects in a large database it keeps of clinical trials and post-marketing data, though the study is interesting enough to warrant further research, said a spokesman for the drug maker Novartis AG.

“We have done a review of our safety database…We’re not seeing reporting of these adverse events. But we will be conducting further studies to better understand,” he said.

The side effect was detected by Dr. Ellin Berman and colleagues at the Memorial Sloan-Kettering Cancer Center in New York after some patients on the drug developed low levels of serum phosphate, a mineral important in bone formation.

The new finding was based on just 16 patients with low mineral levels, and the full significance of the discovery has yet to be ascertained, the company noted.

Glivec, or Gleevec as it is known in the United States, was approved 5 years ago. The drug has transformed life expectancy for people with chronic myelogenous leukaemia (CML) and gastrointestinal stromal tumuors (GIST). Five years of use shows patients taking Glivec have a 90 percent survival rate.

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