Clinical response of carboplatin-based chemotherapy and its association to genetic polymorphism in lung cancer patients from North India - A clinical pharmacogenomics study.

Purpose: Lung cancer mostly diagnosed at advanced inoperable stages; thereby, the chemo-, radiation-, targeted or immune-therapy alone or in combination remains the treatment of choice. In chemotherapy, platinum-based compounds such as cisplatin and carboplatin and third-generation drugs such as docetaxel, paclitaxel, gemcitabine, and vinorelbine are widely used. The beneficial therapeutic outcome of the chemotherapy alone or in combination with radiation (chemoradiation) and/or development of drug resistance depends on the inter-individual genetic differences. Hence, this study was carried out to find gene biomarker that could be useful in the diagnosis of the disease and to predict the outcome of chemo/chemoradiation therapy in ethnic North Indian population.

Materials And Methods: In this clinical study, lung cancer (n = 52) patients from North Indian population were recruited. All the patients were treated with carboplatin target area under curve-5 in combination with third-generation drugs (gemcitabine 1.2 mg/m; paclitaxel 175 mg/m; and etopside 100 mg/m) and radiation therapy. The genomic DNA was isolated from the blood sample and performed polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism.

Results: We found hazard ratio to be significantly higher for XPDLys751Gln (hazard ratio [HR] =2.11, 95% confidence interval [CI]: 0.98-4.53, P = 0.056) and IL1 β511C/T (HR = 9.9, 95% CI: 2.55-38.40, P = 0.001). GSTT1 null (HR = 0.39, 95%CI: 0.18-0.84, P = 0.017) genotype has better response to chemotherapy. Generalized multidimensional reduction model suggested that IL1RN (cross-validation consistency [CVC] =10/10, P = 0.054) and XRCC1399Gln, GSTM1 (CVC = 10/10, P = 0.001) as best predicted model in lung cancer patients to the treatment response.

Conclusion: Genetic polymorphisms and single nucleotide polymorphisms in DNA repair gene (XRCC1, XPD) and drug-metabolizing gene (GSTM1 and GSTT1) could serve as genetic biomarkers in lung cancer patients treated with the above indicated chemotherapy. Based on genotype and chemotherapy treatments, the toxicity effects can be minimized, this will help in the development of personalized medicine in future with better efficacy.