After an accelerated approval from the FDA in 2014, the makers of idelalisib have decided to withdraw the previously approved indications for relapsed follicular B-cell non-Hodgkin lymphoma and relapsed small lymphocytic leukemia, according to a press release. 

Idelalisib is a twice-daily oral treatment that acts by inhibiting phosphoinositide 3-kinase and blocking P110δ.

Initial accelerated approval of idelalisib for follicular lymphoma and small lymphocytic leukemia was based on phase 2 clinical trial results showing a 54% objective response for follicular lymphoma and a 58% objective response for small lymphocytic leukemia. Continued approval was contingent on further trials showing continued clinical benefit. Patient enrollment in confirmatory trials had been a challenge due to the evolving landscape of cancer treatments, which led the company to withdraw the continued approval applications for these indications.

Idelalisib has boxed warnings for fatal and serious toxicities: hepatotoxicity, severe diarrhea and colitis, pneumonitis, infections, and intestinal perforation. Serious adverse reactions such as pneumonia, diarrhea, pyrexia, sepsis, and febrile neutropenia occurred in 50% of patients on idelalisib and led to 53% of patients discontinuing treatment.

In the US, idelalisib is still FDA approved to treat relapsed chronic lymphocytic leukemia. In the EU, UK, Canada, Australia, New Zealand, and Switzerland, idelalisib is still approved to treat follicular B-cell non-Hodgkin lymphoma in addition to chronic lymphocytic lymphoma.