Early clinical trial data suggests that topoisomerase-1 payload ADCs retain efficacy in patients previously treated with mirvetuximab. Because mirvetuximab has a different cytotoxic payload, this indicates that targeting the same receptor (FR-alpha) with a different type of toxin is a viable sequencing strategy.

Despite impressive data supporting HMA/Venetoclax, its application in younger, fit patients must be cautious. The pivotal VIALE-A trial excluded key subgroups like FLT3, core binding factor, and certain NPM1 patients, for whom intensive chemotherapy remains the standard.

Real-world data suggests that using one antibody-drug conjugate (ADC) immediately after another is often ineffective. A potential strategy to overcome this resistance is to administer a different class of chemotherapy before starting the second ADC.

The widespread use of PARP inhibitors has altered tumor biology in platinum-sensitive ovarian cancer. A recent meta-analysis of heavily pretreated patients, 97% of whom had prior PARP inhibitor exposure, revealed an objective response rate to subsequent therapy of only 17%—far lower than historical expectations, highlighting a critical unmet clinical need.

The modest benefit of PARP inhibitors in metastatic breast cancer, compared to ovarian cancer, is likely due to resistance induced by prior exposure to DNA-damaging agents like anthracyclines. This explains the clinical rationale for moving PARP inhibitors to earlier treatment settings, such as neoadjuvant or adjuvant therapy, before resistance develops.

Initial studies combining menin inhibitors with venetoclax/azacitidine showed high remission rates but also high mortality. Using each agent at its full, 28-day dose caused severe, fatal myelosuppression, forcing protocol amendments to shorten drug exposure to manage toxicity.

The BRUIN-313 trial successfully compared pirtobrutinib to bendamustine-rituximab (BR). However, BR is no longer the frontline standard of care. This 'straw man' comparator makes it difficult to position pirtobrutinib against current preferred treatments like other BTK inhibitors or venetoclax regimens, limiting immediate clinical applicability.

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.

While pirtobrutinib is effective after covalent BTK inhibitors, the reverse is unproven. Starting with pirtobrutinib frontline raises a critical unanswered question about whether patients will still respond to older covalent inhibitors, complicating sequencing decisions, especially for younger patients.