A major limitation of menin inhibitor monotherapy is acquired resistance. Up to 39% of patients on revumenib develop mutations in the menin (MEN1) gene. These mutations prevent the drug from binding to its target, leading to rapid relapse and highlighting the need for combination therapies or next-generation agents.

Clinical data suggests that using time-limited venetoclax-BTK inhibitor combinations in the frontline setting mitigates the emergence of BCL2 or BTK resistance mutations. This provides a key biological rationale supporting this approach, as it preserves future treatment options and allows for successful retreatment.

While the new CML drug Asciminib demonstrates better efficacy, its most significant advantage is superior tolerability. Clinical trial data shows it causes significantly fewer treatment discontinuations due to adverse events compared to both Imatinib and second-generation TKIs, improving patient adherence and quality of life.

Despite targeting core driver mutations NPM1 and KMT2A, Menin inhibitors as monotherapy show low (20-25%) and brief responses in AML. This subverts the expectation that targeting a primary driver would be highly curative (like arsenic in APL), suggesting these leukemias have other critical survival pathways.

When an AML patient presents with multiple targetable mutations (FLT3, NPM1, IDH), clinicians follow a treatment hierarchy. FLT3-targeted therapy is typically the first choice due to its aggressive phenotype. Menin inhibitors for NPM1 are next, followed by IDH inhibitors, guiding treatment decisions in complex cases.

Similar to FLT3 inhibitors like midostaurin, which failed in the relapsed setting but succeeded upfront, menin inhibitors are expected to show dramatically better efficacy when combined with standard induction or HMA/Venetoclax in newly diagnosed patients.

Unlike continuous BTK inhibitor therapy, using a BTK inhibitor as part of a time-limited combination regimen does not appear to select for resistance mutations. This crucial distinction means that a BTK inhibitor could potentially be used again effectively as a subsequent line of therapy if the patient relapses.

When menin inhibitors are combined with a chemotherapy backbone like induction or Aza/Ven for newly diagnosed AML, the risk of differentiation syndrome (DS) is significantly lower than when they are used as monotherapy in the relapsed setting.

Risk stratification in CML is moving beyond BCR-ABL. Additional mutations like ASXL1 are now known to predict poorer outcomes and reduced response to asciminib, while others like GATA2 are favorable, pushing for routine, broader genetic sequencing at diagnosis to personalize therapy.