Patients with a particularly difficult-to-treat form of chronic lymphocytic leukaemia have gained access to a new treatment option in the US after regulators expanded the use of Janssen Biotech/Pharmacyclics' Imbruvica (ibrutinib).
After a priority review, the US Food and Drug Administration has issued a green light for the drug's use in CLL patients with a particular genetic mutation called del 17p, who are known to have the poorest prognosis of all those with the blood cancer.
This is because the mutation is associated with poor responses to standard treatment for CLL, so it is particularly good news that these patients now have an additional option.
Imbruvica works by blocking the enzyme that allows cancer cells to grow and divide, and FDA approval is based on data from a clinical study showing that patients taking the drug experienced a 78% reduction in risk of disease progression or death (progression-free survival) compared to those on GlaxoSmithKline's Arzerra (ofatumumab), as well as a 57% reduction in risk of death (overall survival).
Side effects were also similar between the two treatment groups, with those most commonly associated with Imbruvica including low levels of platelets in the blood, a decrease in infection-fighting white blood cells called neutrophils, diarrhea, low red blood cells (anemia), fatigue, pain in the muscles and bones, upper respiratory tract infection, rash, nausea and fever.
Experts believe that, given its strong efficacy and tolerability, Imbruvica could well revolutionise the treatment of CLL. The drug is approved in the US for CLL as well as mantle cell lymphoma, and the extension of its label to include patients with del 17p makes it the first drug to be specifically approved for this patent population.
The FDA has also approved a change in the drug's labelling to reflect the fact that Imbruvica’s clinical benefit in treating CLL has now been verified, after having initially been given accelerated based on its effect on overall response rate.