Preemptive TPMT Genotyping and Adherence to Genotype-Based Therapeutic Recommendations Reduces the Healthcare Cost in Patients Receiving Azathioprine or 6-Mercaptopurine for Autoimmune Diseases

Proactive pharmacogenomics in azathioprine-treated pediatric inflammatory bowel disease at a Chinese tertiary hospital

Background

Despite the emergence of numerous innovative targeted therapies for the management of pediatric inflammatory bowel disease (IBD), azathioprine continues to be a pivotal first-line therapeutic agent. Nonetheless, the considerable frequency of myelosuppression associated with its use warrants careful consideration and further investigation. This study aims to investigate the application of pharmacogenomics in Chinese pediatric IBD treated with azathioprine, and to elucidate its association with the occurrence of myelosuppression.

Methods

We conducted a retrospective analysis to determine the prevalence of pharmacogenetic abnormalities and thiopurine-induced myelosuppression in Chinese pediatric patients with IBD.

Results

Among the 227 patients underwent pharmacogenetic testing, abnormal genetypes occurred in 66 patients, among which 7 patients exhibited aberrant TPMT and 59 had aberrant NUDT15. Of the 58 patients who were treated with azathioprine, 23 cases experienced myelosuppression. All three children with heterozygous mutations in NUDT15 developed leukopenia following azathioprine treatment. Among patients with normal pharmacogenetic results, 20 cases (36.4%) developed myelosuppression, while 35 cases (63.6%) did not. The dose of azathioprine was below the recommended level in guidelines. The mean dose of azathioprine (mg/kg/day) in the myelosuppression group was 1.22 ± 0.32, compared to 1.42 ± 0.42 in the non-myelosuppression group, which represented a statistically significant difference (p < 0.05). Age, gender, and the use of concomitant biologics, mesalazine, or glucocorticoids did not show significant differences between the groups (p > 0.05).

Conclusion

NUDT15 C415T is prevalent in China and is associated with an increased risk of azathioprine-induced myelosuppression. A reduced dose of azathioprine should be considered for Chinese pediatric patients with IBD, even in those with normal pharmacogenetic profiles.

Budget impact analysis of TPMT and NUDT15 pharmacogenomic testing for 6-mercaptopurine in pediatric acute lymphoblastic leukemia patients

BACKGROUND

Pharmacogenomic testing identifies gene polymorphisms impacting drug metabolism, aiding in optimizing treatment efficacy and minimizing toxicity, thus potentially reducing healthcare utilization. 6-Mercaptopurine metabolism is affected by thiopurine methyltransferase ( TPMT ) and nudix hydrolase 15 ( NUDT15 ) polymorphisms. We sought to estimate the budget impact of preemptive pharmacogenomic testing for these genes in pediatric acute lymphoblastic leukemia (ALL) patients from an institutional perspective.

METHODS

A Markov model was constructed to model the first cycle of the maintenance phase of chemotherapy for pediatric ALL patients transitioning between one of three health states: stable, moderately myelosuppressed, and severely myelosuppressed over 16 weeks, with each health state's associated costs derived from the literature. The patient's likelihood to experience moderate or severe myelosuppression based on metabolism phenotype was calculated from the literature and applied on a weekly basis, and the marginal budget impact of preemptive pharmacogenomic testing vs. no pharmacogenomic testing was calculated. One-way sensitivity analysis was conducted to assess parameter influence on results.

RESULTS

Preemptive pharmacogenomic testing of TPMT and NUDT15 provided savings of up to $26 028 per patient during the maintenance phase. In the sensitivity analysis, the cost of outpatient management of moderate myelosuppression had the greatest impact on the budget, resulting in cost savings ranging from $8592 to $30 129 when the minimum and maximum costs of management were used in the model.

CONCLUSION

Preemptive pharmacogenomic testing for TPMT and NUDT15 polymorphisms before initiation of maintenance therapy for pediatric ALL patients yielded considerable cost savings.

Developments in pharmacogenetics, pharmacogenomics, and personalized medicine

The development of Pharmacogenetics and Pharmacogenomics in Western Europe is highly relevant in the worldwide scenario. Despite the usually low institutional support, many research groups, composed of basic and clinical researchers, have been actively working for decades in this field. Their contributions made an international impact and paved the way for further studies and pharmacogenomics implementation in clinical practice. In this manuscript, that makes part of the Special Issue entitled Spanish Pharmacology, we present an analysis of the state of the art of Pharmacogenetics and Pharmacogenomics research in Europe, we compare it with the developments in Spain, and we summarize the most salient contributions since 1988 to the present, as well as recent developments in the clinical application of pharmacogenomics knowledge. Finally, we present some considerations on how we could improve translation to clinical practice in this specific scenario.