The US Food and Drug Administration and Swiss biotechnology company, Serono, have amended the product label for the latter's multiple sclerosis drug, Novantrone (mitoxantrone), to highlight a risk of heart damage associated with the medicine's use.

In a “dear doctor” letter posted on the agency’s website, Serono said that post-marketing surveillance reports had shown that “diminished cardiac function” could occur early on in treatment with Novantrone. The warning has been added to the product’s label together with a warning over the risk of patients developing a form of leukaemia.

The letter stated that potentially fatal congestive heart could failure occur either during therapy or months to years after treatment is stopped, adding that all patients should be carefully assessed for cardiac signs and symptoms before starting treatment.

Serono also highlighted reports of MS and cancer patients treated with Novantrone developing treatment-related leukaemia. “In 1,774 patients with breast cancer who received Novantrone concomitantly with other cytotoxic agents and radiotherapy, the cumulative risk of developing treatment-related [leukaemia], was estimated as 1.1% and 1.6% at five and ten years, respectively,” the company said in the statement.

The firm licensed Novantrone from Amgen back in 2002 [[14/11/02e]], but it’s best selling MS offering is Rebif (interferon beta-1a), which is going from strength to strength, with 2004 sales topping $1.1 billion dollars – a 33% increase on the previous twelve months [[02/02/05c]]. Novantrone brought in $84 million in 2004 sales, which was up 9%.