Current fixed-duration CLL regimens are not MRD-guided, so the test result does not alter the treatment plan. While a negative result is prognostically favorable, its main clinical utility is to provide reassurance. A detectable result can cause unnecessary patient anxiety.

Experts predict that emerging cell-free DNA (ctDNA) tests for lymphoma will shift treatment from fixed durations to a response-adapted approach. Monitoring minimal residual disease via ctDNA will allow clinicians to tailor the length of therapy based on the quality of response.

The SEQUOIA study showed that for high-risk CLL patients (e.g., p53 mutated), extending treatment with zanubrutinib and venetoclax beyond the planned duration significantly increases rates of undetectable MRD. This suggests a personalized, response-adapted approach, challenging the rigid concept of "fixed-duration" for all.

The CLL-17 trial, the first modern head-to-head comparison of major CLL strategies, showed no difference in 3-year survival between fixed-duration and continuous therapy. This landmark finding provides strong evidence that stopping treatment is a safe and effective strategy that reduces long-term toxicity for patients.

In current CLL practice, a positive MRD result after fixed-duration therapy does not trigger a change in treatment, such as extending therapy. It serves as a prognostic tool to inform the patient and physician about the likely duration of remission and the need for closer monitoring.

Despite strong single-agent trial results, experts believe the field is shifting away from continuous monotherapy. The most significant future impact for pirtobrutinib will likely be as a backbone of fixed-duration combination therapies with drugs like venetoclax, aiming for deeper remissions without indefinite treatment.

The UK FLAIR trial demonstrated for the first time that a time-limited regimen (ibrutinib-venetoclax), guided by MRD to a median duration of 27 months, achieved superior progression-free and overall survival compared to continuous ibrutinib therapy in frontline CLL.

A negative Minimal Residual Disease (MRD) result is not a universal surrogate for Progression-Free Survival (PFS). Its predictive power is context-dependent; it's meaningful when comparing similar treatments (e.g., BTKi + BCL2i vs. another BTKi + BCL2i), but less so when comparing entirely different drug classes.

The FLAIR trial's MRD-guided protocol, while effective, created a paradox. Lower-risk, IGHV-mutated patients, who typically do well on shorter treatments, took longer to achieve undetectable MRD. This resulted in them receiving a longer duration of therapy than their higher-risk counterparts, representing likely overtreatment.