Targeting IMPDH to inhibit SAMHD1 in KMT2A-rearranged leukaemia

Area of Science:

• Molecular Biology
• Cancer Research
• Pharmacology

Background:

• Cytarabine (ara-C) and fludarabine (F-ara-A) are crucial in treating leukaemias.
• SAMHD1 protein confers resistance to these drugs.
• Inosine monophosphate dehydrogenase inhibitors (IMPDHi) show promise against KMT2A-rearranged acute myeloid leukaemia (AML).

Purpose of the Study:

• To investigate if IMPDH inhibition enhances ara-C and F-ara-A efficacy in AML.
• To determine if this enhancement is linked to KMT2A status.
• To elucidate the mechanism of IMPDH inhibition in AML cells.

Main Methods:

• Phenotypic screening to identify SAMHD1 inhibitors.
• Testing IMPDH inhibitors (IMPDHi) in AML cell lines and primary samples.
• Assessing synergy between IMPDHi and ara-C/F-ara-A.
• Investigating the role of SAMHD1 and KMT2A status.
• Measuring GTP and dGTP levels to understand mechanism.

Main Results:

• Sensitivity to IMPDHi was independent of KMT2A status.
• IMPDHi synergized with ara-C and F-ara-A in a SAMHD1-dependent manner in a subset of AML cells.
• This synergy was not observed in acute lymphoblastic leukaemia cell lines.
• IMPDHi depleted GTP and dGTP, increasing active triphosphate metabolites in SAMHD1-proficient cells.

Conclusions:

• IMPDH inhibition enhances the efficacy of ara-C and F-ara-A in a SAMHD1-dependent manner in certain AML cases.
• The combination of IMPDHi with ara-C and F-ara-A may offer therapeutic benefits for specific AML patient groups.
• Findings suggest a novel therapeutic strategy for AML treatment.