A role for IFNα is further supported by identification of an IFN gene signature within NK cells from reovirus-treated patients.18 Larger numbers of patients, ideally within the context of a formal clinical trial with therapeutic end points, will be needed to confirm any potential use of monocyte count as a biomarker for oncolytic immunotherapy for CLL. The gene discussed is IFNA1; the disease is B-cell chronic lymphocytic leukemia.