A retrospective observational study to evaluate the clinical outcomes and routine management of patients with chronic lymphocytic leukaemia treated with idelalisib and rituximab in the UK and Ireland (RETRO-idel).

Idelalisib (IDL) is an oral first-in-class phosphatidylinositol 3-kinase delta (PI3Kδ) inhibitor approved for chronic lymphocytic leukaemia (CLL) alongside rituximab (R) since 2014. However, little data exist on routine practice. The RETRO-idel was a protocol-led, retrospective study of 110 patients [n = 27 front-line (1L)] who received IDL-R.