Predictive potential role of glutathione S-transferases polymorphisms in response to chemotherapy and breast cancer prognosis

Single nucleotide polymorphisms as the efficient prognostic markers in breast cancer

BACKGROUND

Breast cancer (BC) is known as the most common malignancy in women. Environmental and genetic factors are associated with BC progression. Genetic polymorphisms have been reported as important risk factors of BC prognosis and drug response. Main body: Therefore, in the present review, we have summarized all single nucleotide polymorphisms (SNPs) which have been significantly associated with drug response in BC patients around the world. We have also categorized the reported SNPs based on their related genes functions to clarify the molecular biology of drug responses in BC.

CONCLUSION

The majority of SNPs were reported in detoxifying enzymes, which introduced such genes as the main genetic risk factors during BC drug responses. This review paves the way for introducing a prognostic panel of SNPs for the BC patients in the world.

Impact of glutathione transferases genes polymorphisms in nevirapine adverse reactions: a possible role for GSTM1 in SJS/TEN susceptibility

PURPOSE

Nevirapine (NVP) is used in developing countries as first-line treatment of HIV infection. Unfortunately, its use is associated with common serious adverse drug reactions, such as liver toxicity and the most severe and rare Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). GSTT1 and GSTM1 genes code for enzymes involved in the metabolism of a wide range of drugs. We hypothesized that this gene variability could be implicated in NVP adverse reactions.

METHODS

We analyzed the GSTM1 and GSTT1 null genotypes by multiplex PCR in a population of 181 patients from Mozambique, treated with NVP. A case/control association study was performed. We also counted the number of risk alleles in SJS/TEN patients and in controls, including the GSTM1 null genotype and four previously identified risk alleles in CYP2B6, HCP5, and TRAF3IP2 genes.

RESULTS

Among patients, 27 had developed SJS/TEN and 76 had developed hepatotoxicity during the treatment. The GSTM1 null genotype was more frequent in the cases with SJS/TEN than in the controls (OR = 2.94, P = 0.027). This association is also observed when other risk factors are taken into account, by a multivariate analysis (P = 0.024 and OR = 3.58). The risk allele counting analysis revealed a significantly higher risk for SJS/TEN in patients carrying three or four risk alleles. Moreover, all subjects with five or six risk alleles developed SJS/TEN, while subjects without any risk alleles were present only in the control group.

CONCLUSIONS

We observed an association between GSTM1 and SJS/TEN susceptibility. Moreover, GSTM1 contributes to the definition of a genetic risk profile for SJS/TEN susceptibility.

GSTP1 polymorphism predicts treatment outcome and toxicities for breast cancer

This study aimed to investigate the association of the GSTP1 gene polymorphism with the outcomes and toxicities of treatments in breast cancer. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for the association of GSTP1 polymorphism with tumour response and toxicities, and the hazard ratios (HRs) and 95% CIs were calculated for the association between GSTP1 polymorphism and overall survival (OS). The statistical analysis showed that the GSTP1 polymorphism was not associated with tumour response or OS. A significant increase in the incidence of toxicities was observed (GA vs. AA OR = 1.45, 95% CI = 1.04–2.01, P = 0.028; GG vs. AA OR = 1.47, 95% CI = 1.03–2.10, P = 0.036; recessive model OR = 1.54, 95% CI = 1.13–2.09, P = 0.006; and allele model OR = 1.35, 95% CI = 1.07–1.71, P = 0.011), especially in the chemotherapy ± surgery group (GA vs. AA OR = 1.64, 95% CI = 1.05–2.56, P = 0.030; recessive model OR = 1.72, 95% CI = 1.17–2.54, P = 0.006; and allele model OR = 1.57, 95% CI = 1.11–2.21, P = 0.010). Our results indicate that the GSTP1 polymorphism may be associated with increased toxicity, especially in patients treated with chemotherapy ± surgery.