# IMP dehydrogenase (IMPDH2)

Source: https://onco.cc/targets/impdh2/  
OnCo record `impdh2` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

IMPDH is the bottleneck enzyme for making guanine nucleotides; mycophenolate blocks it to hold back the donor T cells that cause graft-versus-host disease after stem cell transplantation, and the enzyme is over-expressed in fast-growing tumours.

## Summary

Inosine monophosphate dehydrogenase catalyses the rate-limiting step of guanine nucleotide synthesis, and the type 2 isoform is induced in proliferating lymphocytes and in many cancers. Mycophenolate mofetil, a prodrug of the IMPDH inhibitor mycophenolic acid, is used with a calcineurin inhibitor to prevent graft-versus-host disease after allogeneic stem cell transplantation, and IMPDH is also the target of the old antileukaemic drug tiazofurin and part of the action of ribavirin. Because glioblastoma, small-cell lung cancer and other tumours depend on IMPDH2 for nucleotide supply, repurposing mycophenolate as an anticancer agent is in early trials.

## Fields

- Kind: Target
- Last checked: 2026-09-04
- Tags: chembl-gap
- Symbol: IMPDH2
- Class: enzyme
- Biology: A tetrameric NAD-dependent dehydrogenase that oxidises IMP to XMP; lymphocytes rely on this de novo route because they lack an efficient guanine salvage pathway.
- Where found: Activated lymphocytes; Glioblastoma, small-cell lung cancer and other rapidly dividing tumours

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/IMP_dehydrogenase
- UniProt P12268: IMPDH2: https://www.uniprot.org/uniprotkb/P12268/entry
- HGNC:6053 IMPDH2: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:6053
- ChEMBL target CHEMBL2111369: https://www.ebi.ac.uk/chembl/explore/target/CHEMBL2111369

## Connected records

- targets: [Dihydrofolate reductase (DHFR)](https://onco.cc/targets/dhfr/), [GART (trifunctional purine synthesis enzyme)](https://onco.cc/targets/gart/)
- cancers: [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- terms: [Graft-versus-host disease (GVHD) and graft-versus-leukaemia](https://onco.cc/terms/gvhd/)

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JSON: https://onco.cc/api/v1/entities/impdh2.json