Maintenance therapy for acute lymphoblastic leukemia: basic science and clinical translations

Area of Science:

• Oncology
• Pharmacogenomics
• Clinical Pharmacology

Background:

• Maintenance therapy (MT) with methotrexate (MTX) and 6-mercaptopurine (6-MP) is a cornerstone in acute lymphoblastic leukemia (ALL) treatment.
• These drugs interfere with nucleotide synthesis, with thioguanine nucleotides (TGNs) incorporated into DNA (DNA-TG) being a key cytotoxic mechanism.
• Inter-individual variability in MTX and thiopurine metabolism, influenced by genetic polymorphisms (e.g., TPMT, NUDT15), affects efficacy and toxicity, leading to challenges in dose optimization.

Purpose of the Study:

• To review the essential role of MTX and 6-MP in ALL maintenance therapy.
• To discuss the mechanisms of action and the impact of genetic polymorphisms on thiopurine and MTX metabolism.
• To highlight emerging strategies like the Thiopurine Enhanced ALL Maintenance (TEAM) approach and the identification of genetic markers for relapse detection.

Main Methods:

• Review of existing literature on MTX and 6-MP in ALL maintenance therapy.
• Analysis of the role of genetic polymorphisms (TPMT, NUDT15) in thiopurine metabolism and toxicity.
• Discussion of novel therapeutic strategies and biomarkers for ALL relapse.

Main Results:

• MTX and 6-MP are vital for ALL cure, primarily through DNA incorporation of TGNs.
• Genetic variations in TPMT and NUDT15 significantly influence drug metabolism and toxicity, but do not fully explain inter-patient variability.
• The TEAM strategy, adding 6-thioguanine to standard MT, is under investigation to improve outcomes.
• Mutations in key metabolic and DNA repair pathways are linked to early ALL relapses.

Conclusions:

• Personalized MTX and 6-MP dosing, guided by pharmacogenomics, is crucial for optimizing ALL maintenance therapy.
• Understanding genetic influences and downstream metabolites like DNA-TG can help mitigate toxicity and reduce relapse rates.
• Further research into novel therapeutic strategies and early relapse detection biomarkers is essential for improving ALL survival.