Hugues de Lavallade, MD, PhD, King’s College London, London, UK, discusses the PETALs trial (EudraCT 2013-004974-82). This phase III study evaluated ABL kinase domain mutational analysis by next-generation sequencing (NGS) in newly diagnosed chronic-phase chronic myeloid leukemia (CP-CML) patients undergoing first-line treatment with nilotinib alone or nilotinib in combination with pegylated interferon-α2a. This prospective trial demonstrated that NGS can detect low levels of kinase domain mutations in CP-CML patients after only 3-6 months. Dr Lavallade hopes that this trial will pave the way for the revision of the European LeukemiaNet (ELN) guidelines and outlines the potential impact on clinical practice. This interview took place at the American Society of Hematology (ASH) 2019 Annual Meeting and Exposition in Orlando, FL.