Idelalisib (Zydelig, Gilead Sciences) is a first‑in‑class inhibitor of enzymes that regulate important cellular functions including proliferation, cell death and migration. It has a marketing authorisation in the UK for use 'in combination with rituximab for the treatment of adult patients with chronic lymphocytic leukaemia who have received at least 1 prior therapy, or as first‑line treatment in the presence of 17p deletion or TP53 mutation in patients unsuitable for chemo‑immunotherapy'.
The summary of product characteristics lists the following adverse reactions to idelalisib, alone or with rituximab, as affecting more than 10% of patients: infections, neutropenia, diarrhoea, transaminase increase, rash, pyrexia and increased triglycerides. For full details of adverse reactions and contraindications, see the summary of product characteristics.
The recommended dose and schedule in the summary of product characteristics is 150 mg taken orally, twice daily. Treatment is continued until disease progression or unacceptable toxicity; in most cases, treatment can be resumed at 100 mg twice daily when the adverse event has been resolved. Idelalisib is priced at £3,114.75 for 60 150‑mg tablets (BNF 2015). The mean cost of a 1‑year treatment course for idelalisib is £37,922. The company has a simple discount agreement that provides a discount to the list price of idelalisib. The level of the discount is commercial in confidence.