The US FDA has given its blessing to the use of Johnson & Johnson/AbbVie's Imbruvica as the first chemotherapy-free treatment option for newly-diagnosed chronic lymphocytic leukaemia (CLL) patients.
The approval means that Imbruvica (ibrutinib) - a first-in-class drug that has shown impressive efficacy in extending progression-free survival (PFS) in clinical trials - can now be given to CLL patients regardless of the treatment history.
First approved in 2014, BTK inhibitor Imbruvica has already achieved blockbuster status with sales in excess of $1bn in 2015 from its current indications of second-line therapy for CLL and mantle cell lymphoma (MCL) and the treatment of Waldenström's macroglobulinaemia.
The continued expansion into new patient populations keeps the product on course to meet its projected peak sales forecasts of up to $10bn which if reached would justify AbbVie's $21bn acquisition of Imbruvica developer Pharmacyclics which closed last year.
Earlier this year, AbbVie's chief financial officer William Chase acknowledged that "a significant portion of our valuation for Pharmacyclics is attributed to advancing in the first-line therapy in treatment-naïve CLL patients".
The approval is based on the results of the RESONATE-2 trial, which compared Imbruvica to chlorambucil in 269 treatment-naïve patients with CLL or small lymphocytic lymphoma (SLL) aged 65 years or older.
In the trial, Imbruvica reduced the risk of disease progression or death by 84% compared to chlorambucil, with the median PFS not reached after nearly 19 months. AbbVie and J&J's drug also achieved partial or complete responses in 82% of patients, compared to 35% of the chemotherapy group.
Michael Severino, AbbVie's chief scientific officer, said: "We believe RESONATE-2 represents a practice-changing study that will set a new treatment standard for many treatment-naïve patients."
CLL is a slow-progressing cancer of the bone marrow and blood and is the most common leukaemia diagnosed in adults in western countries, with around 14,600 cases diagnosed in the US each year.
With the FDA approval in hand, Imbruvica remains on course to bring in revenues to AbbVie of "at least $1.8bn this year", according to Chase.
The drug is also is also being evaluated in mid- to late-stage trials in follicular lymphoma, marginal zone lymphoma, diffuse large B-cell lymphoma, multiple myeloma, graft versus host disease and pancreatic cancer, as well as in a number of combination studies with checkpoint inhibitors.
The broad potential of BTK inhibitors was also exemplified by AstraZeneca's recent decision to spend $4bn for a majority stake in Acerta - with an option to acquire the company outright for another $3bn - in order to get hold of Imbruvica rival acalabrutinib.