Gene Expression and Polymorphisms of DNA Repair Enzymes: Cancer Susceptibility and Response to Chemotherapy

First-Line Treatment with Olaparib for Early Stage BRCA-Positive Ovarian Cancer: May It Be Possible? Hypothesis Potentially Generating a Line of Research

Olaparib is currently approved in maintenance treatment of advanced ovarian cancer after response to first-line chemotherapy for breast related cancer antigens (BRCA) mutated patients. The use of this agent is based on data from SOLO1 study that observed a decreased risk of disease progression or death and a median progression-free survival about 36 months longer in case of therapy with olaparib. However, this trial recruited only patients with advanced stage ovarian cancer. The aim of this review is to retrace the available data in order to clarify the potential efficacy and feasibility of olaparib administration in newly diagnosed epithelial ovarian cancer also in early stages.

Rucaparib: An emerging parp inhibitor for treatment of recurrent ovarian cancer

Recently, Poly-ADP-Ribose Polymerase (PARP) inhibitors are one of the most intensively studied group of antiblastic agents for the management of recurrent ovarian cancer. Among this family, Olaparib was the first to be approved by European Medicines Agency as maintenance therapy post-response to platinum-based chemotherapy for recurrent ovarian cancer in women with deleterious BRCA1/2 mutation. Following that, the Food and Drug Administration (FDA) approved Olaparib monotherapy as fourth or later line of treatment in advanced ovarian cancer with deleterious germ-line BRCA1/2 mutation. On March 2017, Niraparib, was approved as maintenance treatment of patients with recurrent epithelial ovarian, who are in complete or partial response to platinum-based chemotherapy, independently of BRCA mutation. Rucaparib inhibits PARP-1, 2 and 3, PARP-4, -12, -15 and -16, as well as tankyrase 1 and 2. On December 2016, it was granted accelerated approval by the FDA, based on data from two multicenter, single arm, phase II trials that evaluated the efficacy of Rucaparib in patients with deleterious, germline and/or somatic BRCA mutation-associated, advanced OC, who have been treated with two or more lines of chemotherapy. The maximum tolerated dose reported was 600 mg twice a day administered orally. Phase III studies are currently ongoing to further validate the efficacy of Rucaparib in the treatment setting and explore its usefulness in a maintenance setting as well. The focus of our review is to report the most recent investigations and clinical progress regarding Rucaparib for treatment of recurrent ovarian cancer.

Pharmacogenetics of platinum-based chemotherapy in non-small cell lung cancer: predictive validity of polymorphisms of ERCC1

INTRODUCTION

The efficacy of platinum-based chemotherapy for patients with non-small cell lung cancer (NSCLC) is limited by chemoresistance. Platinum drugs damage DNA by introducing intrastrand and interstrand crosslinks which result in cell death. Excision repair cross-complementing 1 (ERCC1) is a member of the nucleotide excision repair (NER) pathway which erases such defects. Single nucleotide polymorphisms (SNPs) in ERCC1 impair this activity and have been suggested to predict the response to chemotherapy. Area covered: Among the polymorphisms of proteins involved in uptake, metabolism, cytotoxicity and efflux of platinum drugs, codon 118 C/T and C8092A in ERCC1 are the best characterized SNPs studied for their predictive power. Here, the divergent results for studies of these markers in NSCLC are summarized and the reasons for this contradictory data discussed. Expert opinion: Cytotoxicity of platinum compounds comprise complex cellular processes for which DNA repair may not constitute the rate limiting step. These drugs are administered as doublets to histologically diverse patients and, furthermore, the NER pathway in ERCC1 wildtype cohorts may be still impaired by the chemotherapeutics applied. At present, assessment of a limited number of polymorphism in DNA repair proteins is not reliably associated with response to treatment in NSCLC patients.

ERCC1 SNPs as Potential Predictive Biomarkers in Non-Small Cell Lung Cancer Patients Treated With Platinum-Based Chemotherapy

Polymorphisms in ERCC1, XPD, and XRCC1 were examined for (a) association with the clinical outcome of 107 non-small cell lung cancer patients receiving front-line platinum-based chemotherapy, and (b) correlation with the ERCC1 mRNA levels of 176 chemo-naive primary tumors. The ERCC1-C8092 allele and the number of ERCC1 polymorphic variants (C8092A and Asn118Asn) were associated with progression-free survival. In non-squamous histology, tumoral ERCC1 mRNA levels were lower in patients homozygous for ERCC1-C8092 as compared with the patients carrying the A allele (p = .024). These findings merit investigation in larger cohorts of patients treated with uniform regimens.

Correlation of apolipoprotein A-I kinetics with survival and response to first-line platinum-based chemotherapy in advanced non-small cell lung cancer

The aim of this study was to determine whether apolipoprotein A-I (ApoA-I) kinetics predict the overall survival in patients with advanced-stage non-small cell lung cancer (NSCLC) during platinum-based first-line therapy. A total of 125 NSCLC patients from January 2008 to September 2014 were retrospectively reviewed. Serum ApoA-I level was measured at baseline and thereafter at the start of each palliative chemotherapy cycle for all patients. Patients were divided into four groups according to ApoA-I kinetics. Patients whose ApoA-I ≥ 1.01 g/L and never decreased during treatment, patients whose ApoA-I ≥ 1.01 g/L and decreased (ApoA-I < 1.01 g/L) at least one time during treatment, patients whose ApoA-I < 1.01 g/L and normalized (ApoA-I ≥ 1.01) at least one time during treatment, and patients whose ApoA-I < 1.01 g/L and never normalized during treatment were assigned to non-decreased, decreased, normalized, and non-normalized ApoA-I groups, respectively. Overall survival rates were significantly different between the four groups, with 2-year survival rates of 88.6 and 17.5 % for the non-decreased and the decreased ApoA-I groups, respectively, and none survived 2 years later in the normalized and the non-normalized ApoA-I groups. When compared with the non-decreased group, the hazard ratios of death were 0.05, 0.44, and 1.73 in the normalized, decreased, and non-normalized groups, respectively (P < 0.001). Normalization of ApoA-I was associated with a low risk of progression, whereas patients with a decreased level of ApoA-I showed a progression of disease in most cases. ApoA-I can be a novel, widely available biomarker for patients with NSCLC.

Can pharmacogenetics explain efficacy and safety of cisplatin pharmacotherapy?

Several recent pharmacogenetic studies have investigated the variability in both outcome and toxicity in cisplatin-based therapies. These studies have focused on the genetic variability of therapeutic targets that could affect cisplatin response and toxicity in diverse type of cancer including lung, gastric, ovarian, testicular, and esophageal cancer. In this review, we seek to update the reader in this area of investigation, focusing primarily on DNA reparation enzymes and cisplatin metabolism through Glutathione S-Transferases (GSTs). Current evidence indicates a potential application of pharmacogenetics in therapeutic schemes in which cisplatin is the cornerstone of these treatments. Therefore, a collaborative effort is required to study these molecular characteristics in order to generate a genetic panel with clinical utility.

Dynamic volume perfusion CT in patients with lung cancer: baseline perfusion characteristics of different histological subtypes

OBJECTIVE

To evaluate dynamic volume perfusion CT (dVPCT) tumor baseline characteristics of three different subtypes of lung cancer in untreated patients.

MATERIALS AND METHODS

173 consecutive patients (131 men, 42 women; mean age 61 ± 10 years) with newly diagnosed lung cancer underwent dVPCT prior to biopsy. Tumor permeability, blood flow (BF), blood volume (BV) and mean transit time (MTT) were quantitatively assessed as well as tumor diameter and volume. Tumor subtypes were histologically determined and compared concerning their dVPCT results. dVPCT results were correlated to tumor diameter and volume.

RESULTS

Histology revealed adenocarcinoma in 88, squamous cell carcinoma in 54 and small cell lung cancer (SCLC) in 31 patients. Tumor permeability was significantly differing between adenocarcinoma, squamous cell carcinoma and SCLC (all p<0.05). Tumor BF and BV were higher in adenocarcinomathan in SCLC (p = 0.001 and p=0.0002 respectively). BV was also higher in squamous cell carcinoma compared to SCLC (p = 0.01). MTT was not differing between tumor subtypes. Regarding all tumors, tumor diameter did not correlate with any of the dVPCT parameters, whereas tumor volume was negatively associated with permeability, BF and BV (r = -0.22, -0.24, -0.24, all p<0.05). In squamous cell carcinoma, tumor diameter und volume correlated with BV (r = 0.53 and r = -0.40, all p<0.05). In SCLC, tumor diameter und volume correlated with MTT (r = 0.46 and r = 0.39, all p<0.05). In adenocarcinoma, no association between morphological and functional tumor characteristics was observed.

CONCLUSIONS

dVPCT parameters are only partially related to tumor diameter and volume and are significantly differing between lung cancer subtypes.

ERCC1/BRCA1 expression and gene polymorphisms as prognostic and predictive factors in advanced NSCLC treated with or without cisplatin

BACKGROUND

The FAST was a factorial trial in first-line treatment of advanced non-small-cell lung cancer (NSCLC), addressing the role of replacing cisplatin with a non-platinum agent. The prognostic and predictive effect of ERCC1/BRCA1 expression and ERCC1/XPD/XRCC1-3 gene polymorphisms on outcomes of patients was examined.

METHODS

Patients were randomised to receive treatment with or without cisplatin. ERCC1/BRCA1 expression was determined by immunohistochemistry. ERCC1 (C8092A, C118T), XPD (Lys751Gln), XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) gene polymorphisms were evaluated on tumour DNA by TaqMan allelic discrimination assay.

RESULTS

Tumour samples were available from 110 of 433 patients enrolled: 54.7% were ERCC1 positive and 51.4% were BRCA1 positive. Overall, ERCC1-negative patients had better response rate (P=0.004), progression-free survival (P=0.023) and overall survival (P=0.012) compared with positive ones, with no statistically significant treatment interaction. The BRCA1-positive patients showed numerically better outcomes, although not statistically significant, with no treatment interaction. Among DNA repair gene polymorphisms, only XRCC1 Gln/Gln genotype evidenced a potential prognostic role (P=0.036).

CONCLUSION

This study confirms the prognostic role of ERCC1 expression and XRCC1 (Arg399Gln) polymorphism in advanced NSCLC treated with first-line chemotherapy. None of these biomarkers was shown to be a specific predictive factor of cisplatin efficacy.

DNA repair and cytotoxic drugs: the potential role of RAD51 in clinical outcome of non-small-cell lung cancer patients

Many of the cytotoxic drugs used in the treatment of non-small-cell lung carcinoma patients can interfere with DNA activity and the definition of an individual DNA repair profile could be a key strategy to achieve better response to chemotherapeutic treatment. Although DNA repair mechanisms are important factors in the prevention of carcinogenesis, these molecular pathways are also involved in therapy response. RAD51 is a crucial element in DNA repair by homologous recombination and has been shown to interfere with the prognosis of patients treated with chemoradiotherapy. There is increasing evidence that genetic polymorphisms in repair enzymes can influence DNA repair capacity and, consequently, affect chemotherapy efficacy. We conducted this review to show the possible influence of the RAD51 genetic variants in damage repair capacity and treatment response in non-small-cell lung carcinoma patients.

Individualized Chemotherapy in Advanced NSCLC Patients Based on mRNA Levels of BRCA1 and RRM1

OBJECTIVE

Experimental evidence suggests that the overexpression of breast cancer-specific tumor suppressor protein 1 (BRCA1) gene enhances sensitivity to docetaxel and resistance to cisplatin and ribonucleotide reductase M1 (RRM1) gene overexpression enhances resistance to gemcitabine. To further examine the effect of BRCA1 and RRM1 mRNA levels on outcome in advanced non-small cell lung cancer (NSCLC), we performed this non-randomized phase II clinical trial which tested the hypothesis that customized therapy would confer improved outcome over non-customized therapy.

METHODS

RNA was isolated from fresh tumor tissue. Patients received chemotherapy regimen based on their BRCA1 and RRM1 mRNA levels: both low-cisplatin plus gemcitabine (GP); both high-vinorelbine plus cisplatin (NP); BRCA1 low and RRM1 high-cisplatin plus docetaxel (TP); BRCA1 high and RRM1 low-vinorelbine plus gemcitabine (GN).

RESULTS

From Dec 2005 to Nov 2008, 94 metastatic and locally advanced NSCLC patients from our institute were enrolled in this study. The median age was 58 years old. Among them, 21 patients received GP, 30 patients received TP and 43 patients received NP chemotherapy. GP group had a higher response rate, and longer median time to progression (TTP) and median overall survival (OS) time than the other 2 groups. The response rates in the GP, TP and NP groups were 42.9%, 36.7% and 27.9%, respectively (P=0.568). The median TTP was 5.6, 5.0, 4.8 months (P=0.975), respectively, and the median OS time was 12.5, 11.0, 9.7 months (P=0.808), respectively.

CONCLUSION

Chemotherapy customized according to BRCA1 and RRM1 expression levels is associated with higher response rate and longer TTP and OS time in the GP group. This suggests that BRCA1 and RRM1 mRNA levels could be used as biomarkers in individual therapy in NSCLC.

Impact of two common xeroderma pigmentosum group D (XPD) gene polymorphisms on risk of prostate cancer

Background

DNA repair genes (eg: xeroderma pigmentosum group D, XPD) may affect the capacity of encoded DNA repair enzymes to effectively remove DNA adducts or lesions, which may result in enhanced cancer risk. The association between XPD gene polymorphisms and the susceptibility of prostate cancer (PCa) was inconsistent in previous studies.

Methodology/Principal Findings

A meta-analysis based on 9 independent case-control studies involving 3165 PCa patients and 3539 healthy controls for XPD Gln751Lys SNP (single nucleotide polymorphism) and 2555 cases and 3182 controls for Asn312Asp SNP was performed to address this association. Meanwhile, odds ratio (OR) and 95% confidence intervals (CIs) were used to evaluate this relationship. Statistical analysis was performed with STATA10.0. No significant association was found between XPD Gln751Lys SNP and PCa risk. On the other hand, in subgroup analysis based on ethnicity, associations were observed in Asian (eg. Asn vs. Asp: OR = 1.34, 95%CI = 1.16–1.55; Asn/Asn+Asn/Asp vs. Asp/Asp: OR = 1.23, 95%CI = 1.07–1.42) and African (eg. Asn vs. Asp: OR = 1.31, 95%CI = 1.01–1.70; Asn/Asn vs. Asp/Asp: OR = 1.71, 95%CI = 1.03–7.10) populations for Asn312Asp SNP. Moreover, similar associations were detected in hospital-based controls studies; the frequency of Asn/Asn genotype in early stage of PCa men was poorly higher than those in advanced stage of PCa men (OR = 1.45, 95%CI = 1.00–2.11).

Conclusion/Significance

Our investigations demonstrate that XPD Asn312Asp SNP not the Gln751Lys SNP, might poorly increase PCa risk in Asians and Africans, moreover, this SNPs may associate with the tumor stage of PCa. Further studies based on larger sample size and gene-environment interactions should be conducted to determine the role of XPD gene polymorphisms in PCa risk.

Role of genotyping in non-small cell lung cancer treatment: current status

Non-small cell lung cancer (NSCLC) is a common malignant disease with an extremely poor prognosis. Chemotherapeutic treatment for advanced disease is currently based on histological subtyping, but recent discoveries of genetic alterations in subsets of NSCLC have already changed clinical practice with regard to Egfr mutations as predictive markers of response to gefitinib and erlotinib. This has also paved the way for the integration of molecular analyses into early phase clinical trials, as demonstrated by the clinical development of crizotinib, effective in lung cancer harbouring Alk rearrangements. Similarly, other subgroups of NSCLC carry potentially targetable molecular alterations and their study has the potential to change the diagnostic and therapeutic approach to lung cancer in the near future. In contrast to a wealth of knowledge surrounding genomic alterations in lung adenocarcinomas, fewer data are available concerning squamous cell lung cancer (SCC), although recent data demonstrate that genotyping can provide new therapeutic perspectives in SCC treatment. Moreover, the study of molecular predictive markers of response to chemotherapy aims to improve chemotherapeutic treatment, increasing efficacy and limiting toxicity.

The potential of exploiting DNA-repair defects for optimizing lung cancer treatment

The tumor genome is commonly aberrant as a consequence of mutagenic insult and incomplete DNA repair. DNA repair as a therapeutic target has recently received considerable attention owing to the promise of drugs that target tumor-specific DNA-repair enzymes and potentiate conventional cytotoxic therapy through mechanism-based approaches, such as synthetic lethality. Treatment for non-small-cell lung cancer (NSCLC) consists mainly of platinum-based chemotherapy regimens and improvements are urgently needed. Optimizing treatment according to tumor status for DNA-repair biomarkers, such as ERCC1, BRCA1 or RRM1, could predict response to platinum, taxanes and gemcitabine-based therapies, respectively, and might improve substantially the response of individual patients' tumors. Finally, recent data on germline variation in DNA-repair genes may also be informative. Here, we discuss how a molecular and functional DNA-repair classification of NSCLC may aid clinical decision making and improve patient outcome.

A C118T polymorphism of ERCC1 and response to cisplatin chemotherapy in patients with late-stage non-small cell lung cancer

PURPOSE

To investigate the association between a single-nucleotide polymorphism (SNP) of ERCC1, Asn118Asn (C → T), and the response of patients with late-stage non-small cell lung cancer (NSCLC) (n = 142) to cisplatin-based chemotherapy.

METHODS

The SNP, Asn118Asn (C → T), in codon 118 of ERCC1 was detected using an AllGlo™ Probe-based real-time PCR kit. The short-term clinical outcomes were evaluated by measuring complete and partial responses (CR and PR), whereas progression-free survival (PFS) and overall survival (OS) were determined to indicate long-term outcomes.

RESULTS

The allelic frequencies of the ERCC1 codon 118 were found to be 60.6% (C/C), 33.1% (C/T), and 6.3% (T/T), respectively. Overall, the CR and PR to cisplatin-based treatment were 33.1%. Notably, the response rate of patients carrying an ERCC1 118 C/C allele was more than twofold higher than that of patients with a C/T or T/T genotype (95% confidence interval (CI), 1.065-3.910, P = 0.032). Correspondingly, the long-term median PFS and OS of patients carrying the ERCC1 118 C/C allele were significantly longer than those of patients carrying a C/T or T/T allele (P < 0.01). Besides, positive correlation was observed between the differentiation status and tumor staging as well as the C/C genotype.

CONCLUSIONS

Our results suggest that this polymorphism of ERCC1 at codon 118 is associated with patient response to cisplatin-based chemotherapy in treatments of late-stage NSCLC. Moreover, by assaying this SNP in blood cells, the ERCC1 codon 118 may represent a valuable biomarker in developing individualized treatments for NSCLC patients.

Association of ERCC2/XPD polymorphisms and interaction with tobacco smoking in lung cancer susceptibility: a systemic review and meta-analysis

The association of the two ERCC polymorphisms, Asp312Asn and Lys751Gln, with lung cancer risk remains controversial and inconclusive. To better evaluate the potential role of the two polymorphisms and interaction with tobacco smoking in lung cancer susceptibility presented in diverse populations, we have conducted a meta-analysis based on 26 studies from 24 publications which included analyses of Asp312Asn (7121 cases, 8962 controls) and Lys751Gln (8396 cases, 10510 controls) polymorphisms. Overall, significantly elevated lung cancer risk was associated with ERCC2 312Asn allele(homozygous model: OR=1.20[1.05-1.36], P=0.006; recessive model: OR=1.20[1.06-1.35], P=0.004) and 751Gln allele(homozygous model: OR=1.31[1.17-1.46], P<0.00001; heterozygous model: OR=1.11[1.04-1.19], P=0.003; recessive model: OR=1.23[1.11-1.37], P<0.0001; dominant model: OR=1.15[1.08-1.23], P<0.0001). In ethnic subgroup analyses, significantly increased risk was associated with ERCC2 312Asn allele for both Caucasians and Asians, and 751Gln allele for both Caucasians and Latino-Americans. When stratified by smoking status, significantly elevated risk of both polymorphisms for never-smokers was detected (dominant model, OR=1.46[1.09-1.95] and 1.57[1.19-2.08], P=0.01 and 0.002, respectively). In conclusion, this meta-analysis suggests that the two ERCC2 polymorphisms may contribute to lung cancer susceptibility serving as low-penetrance risk factors. Extremely large-scale evidence would be necessary to confirm the effects on ethnically specific populations and gene-environment interactions.

Association between polymorphisms of DNA repair genes and survival of advanced NSCLC patients treated with platinum-based chemotherapy

BACKGROUND

Single nucleotide polymorphism (SNP) in DNA repair genes can be used to explain the differences in survival of platinum-treated non-small cell lung cancer (NSCLC) patients regardless of their performance status. To define the role of DNA repair gene SNPs in NSCLC patients, we investigated the association between survival and 12 different SNPs of 9 DNA repair genes.

METHODS

340 patients were treated with platinum-based chemotherapy. Polymorphisms were detected by real time PCR with TaqMan probe, using genomic DNA extracted from peripheral blood samples. Multivariate logistic or Cox regression analyses were used to adjust for possible confounding variables.

RESULTS

The median overall survival time was 15 months and it was significantly longer in patients harboring ERCC1 118 C/T or T/T allele: 18 months as compared to 13.8 months for the C/C allele (P=0.014). Subgroup analysis revealed that ERCC1 118 C/T or T/T was associated with increased survival in elderly patients (P=0.018), male (P=0.022), squamous carcinoma (P=0.003), smoker (P=0.076) and those treated with non-gemcitabine/cisplatin or carboplatin (non-GP/GC) regimen (P=0.023). XRCC3C/C was associated with better survival in non-gemcitabine/cisplatin treated patients (P=0.014). Both of CCNH-V270A C/C or C/T and XPD 751 A/A showed a significant longer survival in the squamous cell carcinoma subgroup (P=0.047 and P=0.034 respectively).

CONCLUSION

Present data indicates that ERCC1 118 C/T or T/T might provide a better prognostic predictive marker of NSCLC patients treated with platinum-based chemotherapy, mainly in elderly subgroup, male, squamous carcinoma, smoker and those treated with non-GP/GC regimen.

Establishment of primary mouse lung adenocarcinoma cell culture

Lung cancer is the most common malignant disease worldwide and is the leading cause of death from cancer. Primary cultures derived from lung cancer are essential for understanding abnormal growth function in lung epithelia. In this study, 2 out of 5 primary lung adenocarcinoma cultures derived from DNA repair-deficient mice were established and characterised using electron microscopy and immunostaining. Results of the tumourigenicity tests confirmed that these primary cells are tumourigenic. In conclusion, an effective primary culture method provides a tool for clinical antitumour drug testing.

Chemotherapy-induced neutropenia does not correlate with DNA repair gene polymorphisms and treatment efficacy in advanced non-small-cell lung cancer patients

BACKGROUND

Platinum doublets are standard chemotherapy for advanced non-small-cell lung cancer (NSCLC). The aim of this study was to assess whether neutropenia is: (1) an indicator for treatment efficacy, or (2) associated with specific polymorphisms.

PATIENTS AND METHODS

Four hundred ninety-four patients, treated with cisplatin-docetaxel were retrospectively analyzed. Relative dose intensity (RDI) was assessed for both drugs. Neutrophil counts were assessed only on Day 21 of each cycle. Genotyping was performed for 4 different polymorphisms in ERCC1, XRCC3, XPD-23, and XPD-10.

RESULTS

The median overall survival was 9 months. The mean RDI was 0.94 for cisplatin and 0.93 for docetaxel. Four hundred three patients received ≥ 3 cycles of chemotherapy, and 239 received ≥ 6 cycles. Thirty-one percent developed neutropenia, and 19% had Grade (G)3-4 neutropenia. RDI was lower in patients with neutropenia (G1-4; 0.87-0.93) when compared with those without (G0; 0.94-0.95; P < .02). Male patients (P = .02) had inferior survival when compared with female patients, and ECOG (Eastern Cooperative Oncology Group) 1-2 patients (P < .001) had worse survival when compared with ECOG 0. There was no significant survival difference with respect to Grade of neutropenia (G0, 8.7 vs. G1-2, 11.6 vs. G3-4, 9.6 months; P = .41). In ECOG 0 patients, survival was significantly better for neutropenic G1-4 (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.31-0.96; P = .034) when compared with non-neutropenic (G0) patients. No association was observed between examined polymorphisms and neutropenia.

CONCLUSION

RDI was significantly higher in patients who did not develop neutropenia during treatment, but as the nadir period was not explored in our study, the low occurrence of neutropenia in our cohort is considered underestimated. There was no significant survival difference with respect to grade of neutropenia. Finally, none of the examined single nucleotide polymorphisms (SNPs) were associated with the presence of neutropenia, disease characteristics, response rates, or survival.

Association of DNA Repair Gene Polymorphisms With Response to Platinum-Based Doublet Chemotherapy in Patients With Non–Small-Cell Lung Cancer

Purpose

To identify polymorphisms in DNA repair genes that affect responses to platinum-based doublet chemotherapy in patients with non–small-cell lung cancer (NSCLC).

Patients and Methods

In total, 640 patients with NSCLC who received platinum-based doublet chemotherapy in the National Cancer Center Hospital in Japan from 2000 to 2008 and whose responses were evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) participated in a study of the association between response and genotypes for 30 single nucleotide polymorphisms (SNPs) in 27 DNA repair genes. Candidate SNPs were selected in a discovery set of 201 patients, and their associations were validated in an independent set of 439 patients by prespecified P value criteria.

Results

Homozygotes for the minor allele TP53-72Pro of the Arg72Pro SNP in the TP53 gene showed a better response rate (54.3%) than those for the major allele TP53-72Arg (29.1%; P = 4.4 × 10−5) irrespective of therapeutic regimens, and minor allele homozygotes had significantly longer progression-free and overall survivals than major allele homozygotes (hazard ratio [HR], 0.85; 95% CI, 0.74 to 0.98; P = .020; and HR, 0.86; 95% CI, 0.74 to 0.99; P = .039). Minor allele carriers for SNP Lys940Arg in the poly (ADP-ribose) polymerase 1 (PARP1) gene showed a better response rate to the paclitaxel regimen (45.8%) than to the gemcitabine regimen (10.5%; P for interaction = .019).

Conclusion

Polymorphisms in the TP53 and PARP1 genes are involved in inter-individual differences in the response to platinum-based doublet chemotherapy in patients with NSCLC.

Evaluation of single nucleotide polymorphisms (SNPs) in the p53 binding protein 1 (TP53BP1) gene in breast cancer patients treated with breast-conserving surgery and whole-breast irradiation (BCS + RT)

PURPOSE

TP53BP1 is a key component of radiation-induced deoxyribonucleic acid damage repair. The purpose of this study was to evaluate the significance of a known common single nucleotide polymorphism in this gene (rs560191) in patients treated with breast-conserving surgery and whole-breast irradiation (BCS + RT).

METHODS AND MATERIALS

The population consisted of 176 premenopausal women treated with BCS + RT (median follow-up, 12 years). Genomic deoxyribonucleic acid was processed by use of TaqMan assays. Each allele for rs560191 was either C or G, so each patient was therefore classified as CC, CG, or GG. Patients were grouped as GG if they were homozygous for the variant G allele or CC-CG if they carried at least one copy of the common C allele (CC or CG).

RESULTS

Of the 176 women, 124 (71%) were CC-CG and 52 (29%) were GG. The mean age was 44 years for GG vs. 38 years for CC-CG (p < 0.001). GG was more common in African-American women than white women (69% vs. 13%, p < 0.001) and more commonly estrogen receptor negative (70% vs. 49%, p = 0.02). There were no significant correlations of rs560191 with other critical variables. Despite the fact that GG patients were older, the 10-year rate of local relapses was higher (22% for GG vs. 12% for CC-CG, p = 0.04).

CONCLUSIONS

This novel avenue of investigation of polymorphisms in radiation repair/response genes in patients treated with BCS + RT suggests a correlation to local relapse. Additional evaluation is needed to assess the biological and functional significance of these single nucleotide polymorphisms, and larger confirmatory validation studies will be required to determine the clinical implications.

ERCC1, RRM1 and BRCA1 mRNA expression levels and clinical outcome of advanced non-small cell lung cancer

This study was to investigate whether the expressions of DNA repair genes ERCC1 (excision repair cross complementing 1), RRM1 (ribonucleotide reductase subunit M1) and BRCA1 (breast cancer 1) affected clinical outcome in patients with NSCLC. Patients with stage IIIb/IV NSCLC were given platinum-based chemotherapy. Messenger RNA expression levels of ERCC1, BRCA1 and RRM1 were determined by real-time polymerase chain reaction with TaqMan probes in the tumor. The relationship between these three genes with chemoresponse and overall survival was analyzed in this study. Eighty-five patients (median age 59, range 30-78) were enrolled into the study. Median overall survival (OS) was 13 months (range 10.8-15.2). Time to progression (TTP) was 6.1 months (range 5.5-6.7). Patients with low ERCC1 expression benefited more from a platinum-containing regimen (P=0.094). Patients with low RRM1 expression benefited more from a gemcitabine-containing regimen. Patients with high BRCA1 expression benefited more from an anti-tubulin-containing regimen (P=0.046). Partial response rate was 42.4%. A statistically significant difference in OS was seen in patients with low ERCC1 levels compared to patients with high ERCC1 ones. (16.5 vs. 10.0 months, P=0.045). A significant relationship was observed between the expression of ERCC1 and BRCA1 and TTP (6.5 vs. 5.1 months, P=0.001, 5.2 vs. 6.5, P=0.019, respectively). High expression of BRCA1 was associated with better survival in the anti-tubulin-containing regimen subgroup (8.7 vs. 13.0, P=0.035). ERCC1, RRM1 and BRCA1 are promising predictive and prognostic biomarkers in advanced non-small cell lung cancer.