# Mercaptopurine

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

## TL;DR

Mercaptopurine is a daily tablet, or a liquid for children, that keeps acute lymphoblastic leukaemia in remission during the long maintenance phase of treatment.

## Summary

Mercaptopurine, developed by Elion and Hitchings and approved in 1953, is indicated for acute lymphoblastic leukaemia as part of a combination maintenance regimen; daily oral mercaptopurine with weekly methotrexate for two to three years is the backbone of maintenance in every paediatric and adult ALL protocol. Purixan (2014) is an oral suspension that made accurate paediatric dosing possible; the EU authorised the equivalent Xaluprine in 2012. TPMT and NUDT15 genotyping is recommended before starting because poor metabolisers suffer life-threatening myelosuppression on standard doses; hepatotoxicity and a small excess of later malignancy are recognised. Thioguanine is the related agent used in AML.

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-10
- Also known as: 6-MP; Xaluprine
- Tags: nci-list; generic
- Brand: Purinethol / Purixan
- Modality: Thiopurine antimetabolite
- Mechanism: Purine analogue converted to thioguanine nucleotides that are incorporated into DNA and RNA and inhibit de novo purine synthesis; inactivated by TPMT and NUDT15, whose variants dictate dosing.
- Approvals: US 1953: Acute lymphoblastic leukaemia, combination maintenance therapy; US 2014: Oral suspension for ALL maintenance (Purixan); EU 2012: ALL in adults, adolescents and children (Xaluprine oral suspension)

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Mercaptopurine
- US label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/search.cfm?labeltype=all&query=mercaptopurine
- NCI drug page: https://www.cancer.gov/about-cancer/treatment/drugs/mercaptopurine
- EPAR (Xaluprine): https://www.ema.europa.eu/en/medicines/human/EPAR/xaluprine

## Connected records

- drugs: [Methotrexate](https://onco.cc/drugs/methotrexate/), [Thioguanine](https://onco.cc/drugs/thioguanine/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [High-risk acute lymphoblastic leukaemia in children (high-risk B-ALL and T-ALL)](https://onco.cc/cancers/all-paediatric-high-risk/), [Infant acute lymphoblastic leukaemia (KMT2A-rearranged, under one year)](https://onco.cc/cancers/all-infant/), [Standard-risk B-cell acute lymphoblastic leukaemia in children](https://onco.cc/cancers/all-paediatric-standard-risk/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [TPMT and NUDT15 genotyping before thiopurines](https://onco.cc/technologies/tpmt-nudt15-genotyping/)
- trials: [Combination Chemotherapy in Treating Young Patients With Newly Diagnosed High-Risk B Acute Lymphoblastic Leukemia and Ph-Like TKI Sensitive Mutations](https://onco.cc/trials/nct02883049/), [Combination Chemotherapy With or Without Lestaurtinib in Treating Younger Patients With Newly Diagnosed Acute Lymphoblastic Leukemia](https://onco.cc/trials/nct00557193/), [Inotuzumab Ozogamicin and Frontline Chemotherapy in Treating Young Adults With Newly Diagnosed B Acute Lymphoblastic Leukemia](https://onco.cc/trials/nct03150693/), [International Collaborative Treatment Protocol For Children And Adolescents With Acute Lymphoblastic Leukemia](https://onco.cc/trials/nct01117441/), [LCH-IV, International Collaborative Treatment Protocol for Children and Adolescents With Langerhans Cell Histiocytosis](https://onco.cc/trials/nct02205762/), [Phase II Study of Carmustine, Streptozocin, and Mercaptopurine for Refractory or Recurrent Brain Neoplasms](https://onco.cc/trials/nct00004688/), [Therapy for Pediatric Relapsed or Refractory Precursor B-Cell Acute Lymphoblastic Leukemia and Lymphoma](https://onco.cc/trials/nct01700946/)
- terms: [B-ALL risk groups (NCI criteria, ETV6::RUNX1, hyperdiploidy, hypodiploidy, iAMP21, IKZF1, CNS status)](https://onco.cc/terms/b-all-cytogenetic-risk/)
- roadmaps: [Chemotherapy roadmap: mustard gas → curative combinations → the warhead inside smarter drugs](https://onco.cc/roadmaps/chemotherapy-roadmap/), [Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first](https://onco.cc/roadmaps/paediatric-oncology-roadmap/)
- targets: [NUDT15](https://onco.cc/targets/nudt15/)

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