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.

Despite clinical efficacy, menin inhibitor monotherapy provides a relatively short duration of response (4-6 months) in the relapsed/refractory setting. Their main clinical benefit is achieving a deep enough remission to allow patients to proceed to a potentially curative allogeneic stem cell transplant.

While MEN1 mutations cause resistance, they don't explain all treatment failures, especially with agents like Ziftomenib. Other mechanisms, including activation of RTK pathways (RAS, FLT3) and epigenetic bypass, are key drivers of acquired resistance.

Combinations of menin inhibitors with standard chemotherapy are achieving impressively high remission rates (e.g., 89% composite remission) in newly diagnosed KMT2A-rearranged AML. This is a significant development, as this genetic subtype has historically been very challenging to treat effectively.

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.

Preclinical data and early clinical findings suggest menin inhibitors could be effective against rare NUP98-rearranged leukemias. This is based on similarities in downstream pathways to the approved KMT2A and NPM1 mutations, hinting at a broader mechanism of action for this drug class.

Combining menin inhibitors with intensive chemotherapy can decrease the risk of differentiation syndrome, a severe side effect. The chemotherapy debulks the tumor, reducing the number of malignant cells available to cause this inflammatory reaction when they differentiate, improving tolerability.

The activity of menin inhibitors is not strictly limited to patients with KMT2A or NPM1 mutations. Emerging data shows responses in patients with rare NUC98 rearrangements and those with a specific HOXA9 transcriptome signature, suggesting a wider potential use.

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.