Two weeks ago, Roche sent docs in the UK a letter warning them of the risk of osteonecrosis, or jaw bone damage, in patients who are being treated with its Avastin medication and concurrent or previous use of chemotherapy or bisphosphonates. This group of meds are taken to inhibit the loss of bone mass in people with osteoporosis and have been linked to jaw bone damage and thigh fractures (see here).

Avastin is used to treat colorectal, kidney and lung cancer, as well as glioblastoma, but may work to exacerbate soft-tissue damage that plays a role in causing osteonecrosis. So far, there have been 55 cases reported of osteonecrosis, or a rate of less than one in 10,000 patients. Overall, Avastin has been given to about 800,000 cancer patients.

However, the letter was distributed only to docs in the UK. Why not the US? A Roche spokeswoman says European regulators asked Roche to issue a letter. “The vast majority of cases were confounded by other risk factors…The potential risk of Avastin patients developing osteonecrosis is very low, with no evidence of a causal relationship between Avastin therapy and development of osteonecrosis,” she writes. As for the US and other countries, Roche is submitting an updated label to regulators, but for now “we will not be issuing a Dear Doctor letter in the US,” unless the FDA wants one issued.

In other words, patients on different sides of the pond are being treated differently. Pfizer, you may recall, took a similar stance with its Sutent med (see here). In both cases, doctors and patients in the US, where the prescribing info does not mention such a risk, are not being alerted to the same possible side effects as those in the UK. Both drugmakers may be playing by the rules, but that may not help patients. We have asked the FDA for comment and will update if the agency replies.