Population-Specific Distribution of TPMT Deficiency Variants and Ancestry Proportions in Ecuadorian Ethnic Groups: Towards Personalized Medicine

Pharmacogenomics of Chemotherapies for Childhood Cancers in Africa: A Scoping Review

Background

Pharmacogenomics holds significant promise in improving the efficacy and safety of chemotherapy for childhood cancers. However, the field remains underexplored in Africa, where high genetic diversity and substantial disease burdens, including cancers, create unique challenges. This review investigates the current state of pharmacogenomics research in childhood cancer chemotherapies across Africa, focusing on genetic variations influencing chemotherapy efficacy and adverse drug reactions. It also highlights critical gaps, such as limited infrastructure and insufficient healthcare worker knowledge, and emphasizes the importance of capacity-building initiatives in the region.

Methods

A scoping review was conducted encompassing studies published up to September 2024 that examined pharmacogenomic variations associated with chemotherapies in childhood cancer patients across Africa. The review included laboratory genetic analyses and surveys assessing healthcare workers' knowledge, attitudes, and perceptions regarding pharmacogenomics, particularly in the context of pediatric oncology.

Results

A total of 12 genes were identified across eight studies, including TPMT, CYP3A5, MDR1, MAPT, NUDT15, ITPA, IMPDH1, SLC29A1, SLC28A2, SLC28A3, ABCC4, and MTHFR. The most studied genes were TPMT and CYP3A5, which are involved in the metabolism of 6-mercaptopurine (6-MP) and vincristine, respectively. These studies spanned five African countries, including Kenya, Egypt, Zimbabwe, Nigeria, Tunisia, and Libya, and focused primarily on childhood cancers, particularly acute lymphoblastic leukemia. Chemotherapies frequently studied were 6-MP (reported in five studies), vincristine, cyclophosphamide, and methotrexate. Knowledge of pharmacogenomics among healthcare workers in Africa remains low, though a positive attitude towards its clinical applications was observed.

Conclusion

Pharmacogenomic variants, such as TPMT*3A, 3C, and CYP3A53, *6, significantly impact drug metabolism in African children with cancer. However, research remains regionally limited, and gaps in infrastructure and healthcare worker training persist. Expanding research efforts and improving pharmacogenomics capacity through pharmacist training and capacity-building initiatives are essential to advancing personalized medicine in Africa, ultimately improving treatment outcomes for pediatric cancer patients.

Assessing the Occurrence and Influence of Cancer Chemotherapy-Related Pharmacogenetic Alleles in the Chilean Population

BACKGROUND

Pharmacogenomic knowledge as a biomarker for cancer care has transformed clinical practice, however, as current guidelines are primarily derived from Eurocentric populations, this limits their application in Latin America, particularly among Hispanic or Latino groups. Despite advancements, systemic chemotherapy still poses challenges in drug toxicity and suboptimal response. This study explores pharmacogenetic markers related to anticancer drugs in a Chilean cohort, filling a gap in Latin American research. Notably, the influence of native South American Mapuche-Huilliche ancestry.

METHODS

To explore pharmacogenetic markers related to anticancer drugs, we utilized an ethnically Admixed Chilean genome-wide association studies (GWAS) dataset of 1095 unrelated individuals. Pharmacogenomic markers were selected from PharmGKB, totaling 36 level 1 and 2 evidence single nucleotide polymorphisms (SNPs) and 571 level 3 SNPs. Comparative analyses involved assessing SNP frequencies across diverse populations from the 1000 Genomes Project. Haplotypes were estimated, and linkage disequilibrium was examined. Ancestry-based association analyses explored relationships between SNPs and Mapuche-Huilliche and European ancestries. Chi-square distribution with p ≤ 0.05 and Bonferroni's multiple adjustment tests determined statistical differences between allele frequencies.

RESULTS

Our study reveals significant disparities in SNP frequency within the Chilean population. Notably, dihydropyrimidine dehydrogenase (DPYD) variants (rs75017182 and rs67376798), linked to an increased risk of severe fluoropyrimidine toxicity, exhibit an exceptionally low frequency (minor allele frequency (MAF) < 0.005). Nudix hydrolase 15 (NUDT15) rs116855232, associated with hematological mercaptopurine toxicity, is relatively common (MAF = 0.062), and is further linked to Mapuche-Huilliche ancestry. Thiopurine methyltransferase enzyme (TPMT), implicated in severe toxicity to mercaptopurines, SNPs rs1142345 and rs1800460 of TMPT gene demonstrate higher MAFs in Admixed Americans and the Chilean population (MAF range 0.031-0.057). Finally, the variant in the UDP-glucuronosyltransferase 1 gene (UGT1A1) rs4148323, correlated with irinotecan neutropenia, exhibits the highest MAF in East Asian (MAF = 0.136) and Chilean (MAF = 0.025) populations, distinguishing them from other investigated populations.

CONCLUSIONS

This study provides the first comprehensive pharmacogenetic characterization of cancer therapy-related SNPs and highlights significant disparities in SNP frequencies within the Chilean population. Our findings underscore the necessity for inclusive research and personalized therapeutic strategies to ensure the equitable and effective application of precision medicine across diverse global communities.