Example profile of CAR transgene expansion and persistence detected by qPCR in patients with B-ALL. Typical cellular kinetics of the tisagenlecleucel transgene expansion profile after infusion in a patient with B-ALL. The shaded area represents area under the curve (AUC) for up to 28 days. Tlast and Tloss denote the time corresponding to the last quantifiable transgene levels (persistence) and loss of transgene, respectively. Nonquantifiable transgene levels (on days 919 and 1451) are not displayed on this semilog plot. Clast, last measurable level of transgene present. Cmax refers to the maximal expansion of CAR transgene level in a patient, and time corresponding to Cmax is denoted as Tmax. The area of exposure up to a certain period can be quantified and denoted as AUC. Tloss was determined as the first available time point after Cmax when transgene levels dropped below 50 copies per μg of DNA. Patients in whom the Tloss was not observed were considered to have persistence up to and time to the last quantifiable transgene level (Tlast).
