The FDA in America has issued a Dear Healthcare Professional letter regarding cases of lung cancer in clinical trials and during post-marketing surveillance in patients treated with Pfizer’s inhaled insulin (INH), Exubera®▼. This adds to concerns previously expressed by the EMEA .
What is the background to this?
As we previously blogged, Pfizer announced in October 2007 that marketing of Exubera®▼ would stop, due to poor uptake. It is likely that some patients are still using Exubera®▼ as Pfizer put in place a transition programme to supply the product, initially up to 16 January but now extended, up to December 2008 (dependent on stock levels and expiry dates). In addition, some patients may be part of clinical trials.
What does this warning say?
A review of data has found six newly diagnosed cases of primary lung cancer among Exubera®▼-treated patients in clinical trials compared to one case in the comparator treated patients. In addition, there has been one post-marketing report. In trials, the incidence of new primary lung cancer per 100 patient-years of drug exposure was 0.13 for Exubera®▼ patients and 0.02 for those treated with a comparator. All the patients diagnosed with lung cancer had a history of smoking. Pfizer states that due to the small number of cases, it is not possible to determine whether the emergence of these events is linked to Exubera®▼. There is also insufficient information in the report to make an assessment of the statistical significance of this.
What is the current advice around lung function with inhaled insulin?
The summary of product characteristics recommends that all patients should have a baseline lung function examination and a repeat test at six months, and at specified intervals thereafter depending on the results. In addition, patients must have stopped smoking for at least 6 months before starting treatment and must not smoke during therapy with INH. Adverse effects noted include cough and decline in lung function.
Clinicians should attempt to identify patients who have had recent supplies of inhaled insulin, or are part of a clinical trial and explain the circumstances of these concerns and, where appropriate, offer alternative treatment. Patients may have heard about this in the media so we should be ready to respond to enquiries from patients, because, even if they no longer use the product, they are likely to be concerned about the news.
Other developments in this area
In January 2008, Novo Nordisk ended the development of AERx, another inhaled insulin product. The following month, Lilly pulled out from the development of AIR inhaled insulin  and it is unclear whether a third company, Mannkind, will continue with their Technosphere inhaled insulin. Other formulations of insulin (e.g. intranasal) are still in development, so we must remain vigilant to the possibility of an increased risk of lung cancer .
1 – Anon. New Exubera lung cancer warning. Scrip 2008; 3353:1 and 19
2 – Anon. Pfizer drops Exubera, but hope remains for inhaled insulin. Scrip 2007; 3305:18