Transaminitis is frequent and severe in subjects receiving idelalisib monotherapy. (A) An index case of idelalisib-related transaminitis. (B) The fraction of subjects experiencing an ALT elevation of the indicated grade at the indicated time. (C) Swim plot of the indicated toxicities of grade ≥2 at the time that they were first experienced by subjects enrolled in the trial. Other toxicities include one subject with grade 3 rash and 1 subject with grade 3 oral ulcers.