William G. Wierda, MD, PhD, on Fixed-Duration Ibrutinib and Venetoclax in First-Line CLL

CAPTIVATE study was a frontline trial for previously untreated patients where patients received oral therapy, three months of ibrutinib monotherapy and then 12 cycles or 12 months of combined ibrutinib plus venetoclax for previously untreated CLL. This was fixed duration treatment and this trial has been presented in multiple venues and has been published. There were two major cohorts on this study, the fixed duration cohort where all patients received the same treatment and then the MRD cohort where there was randomization based on MRD status at end of the 15 cycles of therapy based on MRD status for additional treatment. But this poster and update focuses on the fixed duration cohort and again is the long-term follow-up. Final analysis, we have about 7 years follow-up on this trial of combined therapy in the frontline setting. It took patients 70 years or younger for enrollment independent of other risk features, so independent of IGHV mutation status. There were patients with 17p mutated TP53 included in that trial. And we have long-term follow-up in terms of progression-free survival and overall survival, which are exceptionally good with this frontline treatment. We don't have a median overall progression-free survival. With the seven-year follow-up, we report the 5 1/2 year progression-free survival at about 76%. We do have a median progression-free survival for patients who have a TP53 abnormality. The median PFS for those patients is about four years, which is a reasonably good outcome. For patients with that high-risk feature of mutated TP53 or 17p deletion, we also did an analysis of outcomes. Progression-free survival correlated with early MRD status. Clearly, end-of-treatment MRD status correlates with progression-free survival. Undetectable MRD status correlates with a longer progression-free survival. But we looked at cycle 7 MRD status and looked among patients with a mutated immunoglobulin gene versus those with an unmutated immunoglobulin gene. And interestingly, we saw that for the unmutated cases, that's the higher-risk patient population for shorter PFS. Overall, there wasn't a correlation with early MRD status on this study. As I said, end-of-treatment MRD status did correlate with long-term outcomes. Interestingly, for the patients with a mutated immunoglobulin gene, there was clear correlation with MRD status, early MRD status and outcomes. Early undetectable MRD status correlated with a longer progression-free survival. We have done also some follow-up and collected data on progression and retreatment and there were patients who have been retreated. We did not see any BTK or PLC gamma 2 mutations. Among the 53 patients who we have samples on and could test for mutations, there were two patients who had BCL2 mutations associated with relapse and progression, but no patients with BTK or PLC gamma 2 mutations. We have 36 patients who have had retreatment, 25 have had ibrutinib monotherapy and 11 have had combined therapy. Most of those patients have responded to treatment and we're still collecting data on the follow-up for those patients. Now the trial is closed. We won't collect any additional follow-up because of the closure of the trial, but we have seen very good outcomes with responses at least among those patients who have had either monotherapy retreatment or combined therapy for their retreatment strategy.