Association of Polymorphisms inAKT1andEGFRwith Clinical Outcome and Toxicity in Non–Small Cell Lung Cancer Patients Treated with Gefitinib

Abstract

EGFR mutations are strongly predictive of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor activity in non-small cell lung cancer (NSCLC), but resistance mechanisms are not completely understood. The interindividual variability in toxicity also points out to the need of novel pharmacogenetic markers to select patients before therapy. Therefore, we evaluated the associations between EGFR and AKT1 polymorphisms and outcome/toxicity in gefitinib-treated NSCLC patients. Polymorphic loci in EGFR, and AKT1, and EGFR and K-Ras mutations were assessed in DNA isolated from blood samples and/or paraffin-embedded tumor from 96 gefitinib-treated NSCLC patients. Univariate and multivariate analyses compared genetic variants with clinical efficacy and toxicity using Fisher's, log-rank test, and Cox's proportional hazards model. AKT1-SNP4 association with survival was also evaluated in 127 chemotherapy-treated/gefitinib-naive patients, whereas its relationship with AKT1 expression and gefitinib cytotoxicity was studied in 15 NSCLC cell lines. AKT1-SNP4 A/A genotype was associated with shorter time-to-progression (P = 0.04) and overall survival (P = 0.007). Multivariate analyses and comparison with the gefitinib-nontreated population underlined its predictive significance, whereas the in vitro studies showed the association of lower AKT1 mRNA levels with gefitinib resistance. In contrast, EGFR-activating mutations were significantly correlated with response, longer time-to-progression, and overall survival, whereas EGFR −191C/A (P < 0.001), −216 G/T (P < 0.01), and R497K (P = 0.02) polymorphisms were strongly associated with grade >1 diarrhea. AKT1-SNP4 A/A genotype seems to be a candidate biomarker of primary resistance, whereas EGFR −191C/A, −216G/T, and R497K polymorphisms are associated with diarrhea when using gefitinib in NSCLC patients, thus offering potential new tools for treatment optimization.

Association Between DNA-repair Polymorphisms and Survival in Pancreatic Cancer Patients Treated with Combination Chemotherapy

“…According to previous analyses [29], patients were grouped as patients without versus with toxicity as well as patients without severe toxicity (grade: 0-2) versus those with severe toxicity (grade: 3-4). n Polymorphisms & PFS As a secondary end point of the study we also evaluated differences in PFS (table 2), and the XPD AspAsn 61 (50.0) 11.2 (9.5-13.0) 8.7 (7.4-9.9) AsnAsn 17 (13.9) 11.6 (9.3-13.9) 8.2 (4.5-11.8) AsnAsn + AspAsn 78 (63.9) 11.2 (9.9-12.6) 0.008 † 8. n Polymorphisms & outcome in gemcitabine monotherapy-treated patients Patients (n = 65) treated with gemcitabine monotherapy were considered for an exploratory ana lysis to endorse the hypothesis of the specific value of DNA-repair polymorphisms in patients treated with platinumbased regimens.…”

“…n Genotyping DNA was isolated from blood samples shipped to the Laboratory Medical Oncology (VU University Medical Center, Amsterdam, The Netherlands), as described previously [29]. Details of genetic variants and methods can be found in the Supplementary material.…”

On the pharmacogenetics of non-small cell lung cancer treatment

“…The haplotype including two functional polymorphisms (AKT1-SNP3 and SNP4) was associated with lower Akt protein levels in tissues from Caucasians and with the lowest apoptotic response of EBVtransformed lymphoblastoids to radiation [71,72]. In 96 Caucasian patients treated with gefitinib, the AKT1-SNP4 A/ A genotype was correlated with shorter OS [73], while AKT1-rs2498804 GT and GG alleles were associated with the occurrence of brain metastases [74]. Similarly, a recent study in Korean NSCLC patients showed that other AKT1 polymorphisms could be used as prognostic markers for patients with early-stage NSCLC, suggesting that several genetic variations in the PI3K/AKT pathway may be prognostic and/or predictive factors of response to different drugs [75].…”

Pharmacogenetic study of patients with advanced non-small cell lung cancer (NSCLC) treated with second-line pemetrexed or pemetrexed–carboplatin

“…These PCRs were performed using 1.2 L of DNA sample and 5 L of reagents, in a total reaction volume of 6.2 L. The reaction mixture underwent the following thermo cycling conditions: 95 • C for 10 min, 40 amplification cycles at 92 • C for 15 s followed by final annealing and extension step at 60 • C for 1 min, as previously described [22]. The analysis of the samples was done in a blinded fashion and related to clinical outcome.…”