TP53 and neutropenia: There were also reports of an increased incidence of p53 mutations following prolonged Nutlin-3a exposure35 and concerns about this effect on the development of new cancers.36 In this study, the most frequently reported treatment-related AEs included thrombocytopenia, nausea, leukopenia, vomiting, and fatigue, and the most common treatment-related grade 3 or 4 AEs were thrombocytopenia, lymphopenia and neutropenia.