Hypothetical model of “overall time to treatment class failure” according to initial continuous BTK inhibitor (acalabrutinib, zanubrutinib, ibrutinib) or finite-duration BCL2 inhibitor–based therapy (obinutuzumab plus venetoclax or ibrutinib plus venetoclax) with BCL2 inhibitor–based retreatment for typical patients with CLL (older adults and with comorbidities). Estimates are given for all patients (top) and the genetic subgroups (below). PFS1: first PFS event after frontline therapy estimated from phase 3 trials in older adult/unfit patients based on data summarized in Table 1; TFS: treatment-free survival (defined as time to next therapy or death); PFS2: PFS from beginning of second-line BCL2 inhibitor–based treatment. Of note, PFS1 and TFS are estimates from phase 3 trials (Table 1) and PFS2 is an educated guess from studies of venetoclax-based salvage treatment.^27,34-36,38  TFS is added on to PFS1 continuously, and median PFS2 is starting a new count for overall estimation of “time to treatment class failure” indicated by the fading of the lanes on the right.