KMT2A and acute lymphoblastic leukemia: As the MLL-r ALL PDX models demonstrated different degrees of response to SNDX-50469 (mice engrafted with MLL-1 and MLL-2 PDXs showed extended remissions while mice engrafted with MLL-7 relapse at <70 days), this enabled assessment of ctDNA as a biomarker for treatment response and disease progression across different clinical scenarios.