Valeria Santini, MD from the University of Florence, Florence, Italy discusses the impact of somatic gene mutations on response to lenalidomide in lower-risk myelodysplastic syndromes (MDS) patients without deletion 5q and patients ineligible for or refractory to erythropoiesis-stimulating agents (ESAs). Over 100 patients without the deletion 5q were treated with lenalidomide in the Phase III MDS-005 trial (NCT01029262). Around 26% of these patients responded to treatment and Dr Santini explains that they wanted to understand the factors that are predictive of response in these patients. The most frequent mutation found was SF3B1 and the majority of patients had ring sideroblasts. However, they did not find one specific mutation that predicts response. ASXL1 mutated patients were found to have a lower response rate. They checked whether there is a gene expression profile that would correlate with and predict response. However, they could not confirm the gene differentiation pattern that was indicated as predictive of response in a previous trial. They are evaluating several possible molecular factors that may be predictive. Recorded at the 2016 American Society of Hematology (ASH) Annual Meeting, held in San Diego, CA.