A phase I/II clinical trial is investigating the use of olaparib in CLL patients stratified by ATM status (11q deletion or ATM mutation: ISRCTN34386131 http://www.isrctn.com/ISRCTN34386131) and phase I studies of talazoparib have been undertaken in haematological malignancies (NCT01399840). Here, ATM is linked to B-cell chronic lymphocytic leukemia.