Association of NUDT15*3 and FPGS 2572C>T Variants with the Risk of Early Hematologic Toxicity During 6-MP and Low-Dose Methotrexate-Based Maintenance Therapy in Indian Patients with Acute Lymphoblastic Leukemia.

Genetic variants influencing the pharmacokinetics and/or pharmacodynamics of the chemotherapeutic drugs used in Acute Lymphoblastic Leukemia (ALL) therapy often contribute to the occurrence of treatment related toxicity (TRT). In this study, we explored the association of candidate genetic variants with early hematological TRT (grade 3-4) occurring within the first 100 days of low-dose methotrexate and 6-mercaptopurine based maintenance therapy (n = 73). Fourteen variants in the following candidate genes were genotyped using allele discrimination assay by real-time PCR: ABCB1, DHFR, GGH, FPGS, MTHFR, RFC1, SLCO1B1, TPMT, and NUDT15. Methotrexate polyglutamate (MTXPG3-5) levels in red blood cells were measured by LC-MS/MS. Early hematological TRT (grade 3-4) was seen in 54.9% of patients. The NUDT15*3 allele was associated with early TRT occurrence [HR: 3.04 (95% CI: 1.5-6.1); p = 0.007]. Sensitivity of early TRT prediction improved (from 30.7% to 89.7%) by considering FPGS variant (rs1544105) carrier status along with NUDT15*3 allele [HR = 2.7 (1.5-4.7, p = 0.008)]. None of the considered genetic variants were associated with MTXPG3-5 levels, which in turn were not associated with early TRT. NUDT15*3 allele carrier status could be used as a stratifying marker for Indian ALL patients to distinguish patients at high or low risk of developing early hematological TRT.

Folyl polyglutamate synthethase (FPGS) gene polymorphisms may influence methotrexate adverse events in South Indian Tamil Rheumatoid Arthritis patients.

The aim of the study was to look for the association of FPGS 2752 G > A (rs1544105), FPGS 1994 A > G (rs10106), and GGH 452 C > T (rs 11545078), GGH -401C > T (rs 3758149) gene polymorphisms with methotrexate (MTX) treatment response and MTX-induced adverse events in South Indian Tamil patients with rheumatoid arthritis (RA). Further the influence of these gene polymorphisms on MTX polyglutamate levels was analyzed. A total of 330 patients with RA were investigated. FPGS gene polymorphisms were analyzed by TaqMan 5'nuclease assay and GGH gene polymorphisms were analyzed by PCR-RFLP. Methotrexate polyglutamates (nmol/L of packed erythrocytes) were measured by liquid chromatography mass spectrometry (LCMS/MS) method. We found that the heterozygous genotype of FPGS rs1544105 [p = 0.02, OR 1.93, 95% CI (1.15-3.35)] and FPGS rs10106 AG genotype [p = 0.01, OR 2.11, 95% CI (1.20-3.71)] were associated with MTX adverse events. FPGS rs1544105 and GGH -401C > T SNPs influenced the polyglutamate levels. None of the investigated SNPs seems to be associated with MTX treatment outcome.

Nonassociation of homocysteine gene polymorphisms with treatment outcome in South Indian Tamil Rheumatoid Arthritis patients.

The aim of the study was to look for any association of MTR 2756A>G and MTRR 66A>G gene polymorphisms with clinical phenotype, methotrexate (MTX) treatment response, and MTX-induced adverse events in South Indian Tamil patients with rheumatoid arthritis (RA). A total of 335 patients with RA were investigated. MTR 2756A>G gene polymorphism was analyzed by PCR-RFLP, and MTRR 66A>G SNP was analyzed by TaqMan 5' nuclease assay. The allele frequencies were compared with HapMap groups. MTR 2756G allele was found to be associated with risk of developing RA. The allele frequencies of MTR 2756A>G and MTRR 66A>G SNPs in controls differed significantly when compared with HapMap groups. Neither of the SNPs influenced the MTX treatment outcome and adverse effects. Neither of the SNPs seems to be associated with MTX treatment outcome and adverse events in South Indian Tamil patients with RA.

Effect of thymidylate synthase (TYMS) gene polymorphisms with methotrexate treatment outcome in south Indian Tamil patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease causing joint damage and significant functional impairment. Methotrexate (MTX) remains the mainstay for the treatment of RA. MTX inhibits several enzymes of the folate and nucleotide pathways. Thymidylate synthase (TYMS) is an important enzyme in the de novo pyrimidine pathway responsible for DNA replication. The two common gene polymorphisms analyzed in TYMS are 28-bp tandem repeat polymorphism and a 6-bp insertion/deletion polymorphism. The present study was carried out to find the role of these TYMS gene polymorphisms with clinical phenotype, treatment response, and MTX adverse events in 254 patients with RA of south Indian Tamil ethnicity. TYMS gene polymorphisms were analyzed by PCR. The allele frequencies of TYMS gene polymorphisms did not differ between good and non-responders. However, the TYMS 28-bp tandem repeat 3R allele was higher in non-responders than in patients undergoing remission [64 vs 51.11%, p = 0.06, OR 0.58, 95% CI (0.34-1.00)]. The TYMS 6-bp deletion allele was higher in non-responders than good responders [78.20 vs 64.92%, p = 0.06, OR 0.51 95% CI (0.27-0.98)]. TYMS 3R allele and TYMS 6-bp deletion allele may favor non-response to MTX in south Indian Tamils. TYMS gene polymorphisms did not influence MTX adverse events.

ATIC 347C>G gene polymorphism may be associated with methotrexate-induced adverse events in south Indian Tamil rheumatoid arthritis.

AIM: To find the association of ATIC 347C>G gene polymorphism with methotrexate (MTX) treatment response and MTX-induced adverse events in south Indian Tamil patients with rheumatoid arthritis. PATIENTS & METHODS: A total of 319 rheumatoid arthritis and 310 healthy controls were recruited for the study and ATIC 347C>G gene polymorphism was analyzed by PCR-RFLP method. RESULTS: The genotype and allele frequencies of ATIC 347 C>G SNP did not differ between good and nonresponders and hence this SNP was not found to be associated with MTX treatment response. However, the ATIC 347 GG genotype (p = 0.02; odds ratio [OR]: 4.46; 95% CI: 1.28-15.52) and mutant G allele was associated with MTX-induced gastrointestinal adverse events (p = 0.01; OR: 2.60; 95% CI: 1.27-5.35). CONCLUSION:  ATIC 347C>G gene polymorphism may be associated with the development of MTX induced gastrointestinal adverse events.

Reduced folate carrier-1 80G > A gene polymorphism is not associated with methotrexate treatment response in South Indian Tamils with rheumatoid arthritis.

Methotrexate (MTX) is the most commonly used disease-modifying drug to treat rheumatoid arthritis (RA). Although there are no reliable molecular markers to predict the treatment response and adverse effects to MTX therapy, the polymorphisms in genes coding for MTX metabolizing enzymes and transporters may play a crucial role. The reduced folate carrier-1 (RFC-1) is a bidirectional anion exchanger which transports MTX and folinic acid. It is reported to influence MTX treatment response and adverse effects in some ethnic populations but not in others. It is also associated with susceptibility to various diseases including systemic lupus erythematosus (SLE). The present study was aimed at investigating the role of RFC-1 80G > A gene polymorphism in association with disease susceptibility, MTX treatment response and the MTX-induced adverse events in the South Indian Tamil patients with rheumatoid arthritis. The RFC-1 80G > A gene polymorphism was investigated in 327 patients with RA and in 322 healthy controls by PCR-RFLP method. It was found that the heterozygous RFC-1 80 GA genotype was associated with protection against RA [p = 0.02, odds ratio (OR) 0.69, 95 % confidence interval (CI) 0.50-0.95]. However, it was not found to be associated with MTX treatment response. The RFC-1 G allele frequency was higher in patients with adverse effects, but the difference was not statistically significant (p = 0.08, OR 1.44, 95 % CI 0.97-2.13). RFC-1 80G > A gene polymorphism confers protection for RA. However, it is not associated with MTX treatment response and MTX-induced adverse effects in South Indian Tamil patients with RA.

Multidrug resistance 1 (MDR1) 3435C>T gene polymorphism influences the clinical phenotype and methotrexate-induced adverse events in South Indian Tamil rheumatoid arthritis.

PURPOSE: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease primarily targeting the synovial joints causing joint damage and significant functional impairment. Methotrexate (MTX) remains the mainstay for the treatment of RA, and approximately 10-30% of the patients fail to attain remission because of inefficacy of the drug or due to development of adverse events. Multidrug resistance 1 (MDR1) gene encodes for permeable glycoprotein (P-gp) which is an integral membrane protein for the transport of chemotherapeutic agents, immunosuppressive drugs etc. MDR1 3435C>T results in a wobble mutation in exon 26 but is associated with altered P-gp expression and reduced P-gp function. The present study was carried out to find the role of MDR1 3435C>T gene polymorphism with clinical phenotype, treatment response, and MTX adverse events in 336 RA and 329 healthy controls of South Indian Tamil ethnicity. METHODS: MDR1 3435C>T gene polymorphism was analyzed by TaqMan 5' nuclease assay. RESULTS: We found MDR1 3435T allele as a risk allele for contributing to high EULAR disease activity [p = 0.02, OR 1.50, 95% CI (1.06-2.13)]. Also, MDR1 3435CT genotype was associated with deforming disease [p = 0.02, OR 1.79, 95% CI (1.11-2.88)]. However, this SNP did not influence the MTX treatment response in these patients. MDR1 3435CT genotype was associated with MTX-induced adverse events [p = 0.01, OR 2.01, 95% CI (1.15-3.52)], and the 3435 TT genotype remained protective for the development of adverse events [p = 0.009, OR 0.40, 95% CI (0.21-0.78)]. Also, the heterozygous 3435 CT genotype was associated with gastrointestinal events [p = 0.02, OR 3.62, 95% CI (1.25-10.47)], and CT genotype remained protective in patients developing infection [p = 0.002, OR 0.05, 95% CI (0.006-0.460)]. CONCLUSION: MDR1 3435C>T gene polymorphism influences the clinical phenotype and adverse events to MTX in the South Indian cohort of patients with RA.