A patient on trastuzumab deruxtecan (TDXD) for seven years with no evidence of disease and no toxicity chose to continue the drug, declining to switch to a standard maintenance regimen. This illustrates a real-world challenge where patient preference and excellent outcomes can override the clinical logic of treatment de-escalation.
In the DB09 trial, the median progression-free survival (40 months) was double the median duration of TDXD treatment (20 months). This discrepancy suggests many patients discontinued the cytotoxic component and effectively entered a maintenance phase, validating the induction-maintenance model even within a continuous therapy trial design.
The standard practice of a 6-8 cycle chemotherapy induction followed by maintenance wasn't a deliberate trial design. It evolved organically from patient intolerance to cumulative toxicities like neuropathy, a limitation newer, less toxic drugs like TDXD don't necessarily share.
The PATINA trial revealed palbociclib, not known for CNS activity, unexpectedly lowered the incidence of CNS progression in triple-positive metastatic breast cancer (13.8% vs 20.4%). This suggests a potential new benefit for this drug in a patient population at high risk for brain metastases.