High frequency of NAT2 slow acetylator alleles in the Malay population of Indonesia: an awareness to the anti-tuberculosis drug induced liver injury and cancer

Economic Evaluation of Multiple-Pharmacogenes Testing for the Prevention of Adverse Drug Reactions in People Living with HIV

Purpose

Pharmacogenetics (PGx) testing is one of the methods for determining whether individuals are at risk of adverse drug reactions (ADRs). It has been reported that multiple-PGx testing, a sequencing technology, has a higher predictive value than single-PGx testing. Therefore, this study aimed to determine the most cost-effective PGx testing strategies for preventing drug-induced serious ADRs in human immunodeficiency virus (HIV)-infected patients.

Patients and Methods

Potential strategies, including 1) single-PGx esting (ie, HLA-B*57:01 testing before prescribing abacavir, HLA-B*13:01 testing before prescribing co-trimoxazole and dapsone, and NAT2 testing before prescribing isoniazid) and 2) multiple-PGx testing as a combination of four single-gene PGx tests in one panel, were all compared to no PGx testing (current practice). To evaluate total cost in Thai baht (THB) and quality-adjusted life years (QALYs) for each strategy-based approach to a societal perspective, a hybrid decision tree and Markov model was constructed. Incremental cost-effectiveness ratios (ICERs) were estimated. Uncertainty, threshold, and scenario analyses were all performed.

Results

Before prescribing HIV therapy, providing single or multiple-PGx testing might save roughly 68 serious ADRs per year, and the number needed to screen (NNS) to avoid one serious ADR was 40. Consequently, approximately 35% and 40% of the cost of ADR treatment could be avoided by the implementation of single- and multiple-PGx testing, respectively. Compared with no PGx testing strategy, the ICERs were 146,319 THB/QALY gained for single-PGx testing and 152,014 THB/QALY gained for multiple-PGx testing. Moreover, the probability of multiple-PGx testing being cost-effective was 45% at the Thai willingness to pay threshold of 160,000 THB per QALY. Threshold analyses showed that multiple-PGx testing remained cost-effective under the range of cost, sensitivity at 0.95–1.00 and specificity at 0.98–1.00.

Conclusion

Single and multiple-PGx testing might be cost-effective options for reducing the incidence of drug-induced serious ADRs in people living with HIV.

Semi-Automated Therapeutic Drug Monitoring as a Pillar toward Personalized Medicine for Tuberculosis Management

Standard tuberculosis (TB) management has failed to control the growing number of drug-resistant TB cases worldwide. Therefore, innovative approaches are required to eradicate TB. Model-informed precision dosing and therapeutic drug monitoring (TDM) have become promising tools for adjusting anti-TB drug doses corresponding with individual pharmacokinetic profiles. These are crucial to improving the treatment outcome of the patients, particularly for those with complex comorbidity and a high risk of treatment failure. Despite the actual benefits of TDM at the bedside, conventional TDM encounters several hurdles related to laborious, time-consuming, and costly processes. Herein, we review the current practice of TDM and discuss the main obstacles that impede it from successful clinical implementation. Moreover, we propose a semi-automated TDM approach to further enhance precision medicine for TB management.

Genetic screening to avoid adverse drug reactions from medication use and approach patients' better outcomes: A lesson learn from the report of the Queen Savang Vadhana Memorial Hospital

Background and Aims

The polymerase chain reaction (PCR) technique is adopted for pharmacogenetic testing and adverse drug reaction (ADR) analysis. Methods: PCR was used for testing of pharmacogenetic markers for HLA and non‐HLA polymorphism related to specific drugs.

Results

Among 76 cases that underwent genetic screening, 7.7%, 11.1%, and 2.7% of the patients were found to be genetically positive for allopurinol, carbamazepine, and abacavir, respectively. Two cases were genetically positive for interferon, and two cases of extensive metabolizers were positive for clopidogrel. One case of a NAT2 slow acetylator for isoniazid was found. Among the 74 cases with complete outcomes, 39.2% showed improvements and 18.9% reported a deterioration. Although no serious ADR was observed, two HLA‐B*5701‐negative cases reported ADRs (2.7%). All patients positive for IL28B were improved. One patient receiving clopidogrel showed improvements, but another showed deterioration. Finally, the outcome of slow acetylation NAT2 was worse without ADR.

Conclusion

PCR‐based pharmacogenetic testing is critical for ADR monitoring in a cost‐effective manner.

Acetylator Status Among Newly Diagnosed and Recurrent Tuberculosis Patients from Kupang, Eastern Part of Indonesia

Purpose

N-acetyltransferase-2 enzyme in the liver, encoded by NAT2 gene, plays a central role in metabolizing tuberculosis (TB) drug isoniazid (INH). Low compliance of patients toward six-month TB therapy and internal host factors, ie comorbid diseases, immune status, and genetic profiles, are factors leading to treatment failure and recurrence of pulmonary TB infection. This study aimed to explore the NAT2 acetylator status among newly diagnosed and recurrent pulmonary TB patients in eastern part of Indonesia.

Patients and Methods

Archived DNA of TB patients (n=124) and healthy controls (n=124) were sequenced, and NAT2 acetylator status was determined, then categorized as fast, intermediate, or slow acetylators. Pulmonary TB patients who had no previous TB treatment history were designated as newly diagnosed pulmonary TB, whereas patients with a history of TB treatment were designated as recurrent pulmonary TB. The demographic, clinical, and microbiological data between pulmonary TB groups were compared, and acetylator status was described among groups.

Results

Male was more significantly prevalent in the recurrent pulmonary TB group (p=0.025), and anemia was more prevalent in new pulmonary TB (p=0.003). The acetylator status in pulmonary TB patients compared to healthy controls were rapid (33.9% vs 48.1%), intermediate (57.8% vs 33.0%), and slow acetylators (8.3% vs 18.9%), respectively. Interestingly, the rapid and intermediate acetylator were significantly more prevalent in pulmonary TB patients than in healthy controls (p=0.023, OR=2.58 (1.12–5.97). Furthermore, no differences were found in acetylator status between new and recurrent pulmonary (p=0.776).

Conclusion

Rapid and intermediate acetylators status predominated the pulmonary TB patients in Kupang, eastern part of Indonesia, postulating different genetic makeup in this area. As the pulmonary TB patients in Kupang exhibit more rapid acetylator phenotype, the acetylator status might be relevant to be checked before TB therapy for adjusting treatment dose to prevent drug resistances.

NAT2 slow acetylator is associated with anti-tuberculosis drug-induced liver injury severity in indonesian population

Aim: We investigated the contribution of NAT2 variants and acetylator status to anti-tuberculosis drug-induced liver injury (AT-DILI) severity. Materials & methods: 100 patients with clinically severe AT-DILI and 210 non-AT-DILI controls were subjected to NAT2 genotyping by direct DNA sequencing. Results: NAT2 slow acetylator was significantly associated with AT-DILI risk (p = 2.7 × 10^-7; odds ratio [95% CI] = 3.64 [2.21-6.00]). Subgroup analysis of NAT2 ultra-slow acetylator revealed a stronger association with AT-DILI risk (p = 4.3 × 10^-6; odds ratio [95% CI] = 3.37 [2.00-5.68]). Subset analysis of NAT2 acetylator status and severity grade confirmed these results in AT-DILI patients with more severe disease whereas fast and intermediate acetylator phenotypes were associated with a decreased AT-DILI risk. Conclusion: We elucidated the role of NAT2 phenotypes in AT-DILI in Indonesian population, suggesting that NAT2 genotype and phenotype determination are important to reduce AT-DILI risk.

Isoniazid acetylation phenotypes in the Sudanese population; findings and implications

Background

Isoniazid (INH) is the mainstay antimicrobial in the treatment of tuberculosis (TB). It is acetlylated in the liver to acetyl-INH. However, there is variation in rate of acetylation of INH among TB patients (i.e. fast, intermediate or slow acetylators) which impacts on the treatment outcomes.

Aim

The isoniazid acetylation phenotypes in the expatriate Sudanese population were determined to provide future guidance since TB is prevalent in Sudan.

Methods

A community-based trial among Sudanese expatriates in Saudi Arabia was undertaken to identify INH-acetylation phenotypes. After overnight fasting, a single dose of 200 mg of INH was given to the volunteers. Three hours later, 5 ml of blood were drawn from each volunteer and prepared for High-Performance Liquid Chromatography (HPLC) analysis. The main outcomes were INH and Acetyl-INH concentrations in plasma and the subsequent Acetyl-INH/INH metabolic ratio (MR).

Results

The findings suggest that slow acetylation is highly prevalent among the study participants (n = 43; 84.31%). Moreover, there was no statistically significant correlation between age and the MR (r = −0.18, P = 0.20). Further, there was no significant association between gender and the MR (P = 0.124). Similarly, no significant association was found between smoking habits and MR (P = 0.24).

Conclusion

Isoniazid phenotyping suggests predominantly slow acetylation among the Sudanese in this sample. The study found no statistically significant associations between the MR and age or gender or smoking.

N-acetyltransferase 2 polymorphism and acetylation profiles in Buginese ethnics of Indonesia

BACKGROUND

N-acetyltransferase 2 (NAT2) is a key enzyme involved in the phase II metabolism of aromatic amines and heterocyclic aromatic amines present in a wide range of xenobiotics. The aim of this study was to investigate the NAT2 polymorphism in the Buginese ethnic group of Indonesia to determine the frequency of NAT2 alleles in this population.

RESULTS

We found six haplotypes consisting of six single-nucleotide polymorphisms and 12 NAT2 genotype variations. NAT2*6A haplotype (42%) showed the highest frequency, followed by NAT2*4 (33%), NAT2*7B (15%), NAT2*5B (5%), NAT2*12A (3%), and NAT2*13 (2%). In terms of phenotypes, the Buginese population comprised 18% rapid acetylators, 40% intermediate acetylators, and 42% slow acetylators.

CONCLUSION

We confirmed the high-frequency slow acetylator phenotype in the Buginese population. The NAT2*6A/*6A genotype was the most frequent slow acetylator genotype, followed by NAT2*6A/*7B. The pattern of NAT2 alleles of Buginese is similar to Southeast Asian populations but not Northeast Asian populations. However, the slow acetylator frequencies in the Buginese population were higher than those in Northeast Asian populations and lower than those in Caucasians and some American populations.

Glutathione S-transferase M1 and T1 null allele frequencies among Indonesian ethnics toward improved disease risk assessment

Genetic variations in the glutathione S-transferase genes GSTT1 and GSTM1 have been widely studied, and homozygous deletions or null genotypes have been reported in different populations. Previous studies suggest that individuals who are homozygous-null at the GSTM1 or GSTT1 locus may have an increased risk of environmentally related cancers and drug-induced hepatotoxicity. The aim of the present study was to determine the GSTM1 and GSTT1 polymorphisms in 154 healthy, unrelated individuals from the Javanese-Sundanese and Malay ethnic populations of Indonesia to provide a resource for improving the prognosis of possible susceptibilities in specific populations. The subjects were genotyped for the presence of GSTM1 and GSTT1 using the multiplex polymerase chain reaction technique. The GSTM1-null genotype was more frequent among Javanese-Sundanese ethnics (99%) than among the Indonesian Malay (67.2%). Similarly, Javanese-Sundanese ethnics showed a higher frequency of the GSTT1-null genotype (66.7%) than the Indonesian Malay (36.2%). Analysis of the combined distribution of the GSTM1 and GSTT1 genes revealed that 66.7% of the individuals from the Javanese-Sundanese population lack both the genes, whereas only 21.1% of the Indonesian Malay is GSTM1-null and GSTT1-null. This study contributes significant information on the variability of GSTT1 and GSTM1 gene polymorphisms worldwide, which can provide new knowledge about the relationship between ethnicity and the prevalence of certain diseases.