Fcγ receptors and immunomodulatory antibodies in cancer.

The discovery of both cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) as negative regulators of antitumour immunity led to the development of numerous immunomodulatory antibodies as cancer treatments. Preclinical studies have demonstrated that the efficacy of immunoglobulin G (IgG)-based therapies depends not only on their ability to block or engage their targets but also on the antibody's constant region (Fc) and its interactions with Fcγ receptors (FcγRs). Fc-FcγR interactions are essential for the activity of tumour-targeting antibodies, such as rituximab, trastuzumab and cetuximab, where the killing of tumour cells occurs at least in part due to these mechanisms. However, our understanding of these interactions in the context of immunomodulatory antibodies designed to boost antitumour immunity remains less explored. In this Review, we discuss our current understanding of the contribution of FcγRs to the in vivo activity of immunomodulatory antibodies and the challenges of translating results from preclinical models into the clinic. In addition, we review the impact of genetic variability of human FcγRs on the activity of therapeutic antibodies and how antibody engineering is being utilized to develop the next generation of cancer immunotherapies.

A pleiotropic ATM variant (rs1800057 C>G) is associated with risk of multiple cancers.

ATM (ataxia-telangiectasia mutated) is an important cell-cycle checkpoint kinase required for cellular response to DNA damage. Activated by DNA double strand breaks, ATM regulates the activities of many downstream proteins involved in various carcinogenic events. Therefore, ATM or its genetic variants may have a pleiotropic effect on cancer development. We conducted a pleiotropic analysis to evaluate associations between genetic variants of ATM and risk of multiple cancers. With genotyping data extracted from previously published genome-wide association studies of various cancers, we performed multivariate logistic regression analysis, followed by a meta-analysis for each cancer site, to identify cancer risk-associated single-nucleotide polymorphisms (SNPs). In the ASSET two-sided analysis, we found that two ATM SNPs were significantly associated with risk of multiple cancers. One tagging SNP (rs1800057 C>G) was associated with risk of multiple cancers (two-sided P = 5.27 × 10-7). Because ATM rs1800057 is a missense variant, we also explored the intermediate phenotypes through which this variant may confer risk of multiple cancers and identified a possible immune-mediated effect of this variant. Our findings indicate that genetic variants of ATM may have a pleiotropic effect on cancer risk and thus provide an important insight into common mechanisms of carcinogenesis.

Genetic variants of BIRC3 and NRG1 in the NLRP3 inflammasome pathway are associated with non-small cell lung cancer survival.

The nod-like receptor protein 3 (NLRP3) is one of the most characterized inflammasomes, and its genetic variation and functional dysregulation are involved in pathogenesis of several cancers. To systematically evaluate the role of NLRP3 in predicting outcomes of patients with non-small cell lung cancer (NSCLC), we performed a two-phase analysis for associations between genetic variants in NLRP3 inflammasome pathway genes and NSCLC survival by using a published genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. We used multivariate Cox proportional hazards regression analysis with Bayesian false discovery probability (≤0.80) for multiple testing correction to evaluate associations between 20,730 single-nucleotide polymorphisms (SNPs) in 176 genes and overall survival of 1,185 NSCLC patients from the PLCO trial. We further validated the identified significant SNPs in another GWAS dataset with survival data from 984 NSCLC patients of the Harvard Lung Cancer Susceptibility (HLCS) study. The results showed that two independent SNPs in two different genes (i.e., BIRC3 rs11225211 and NRG1 rs4733124) were significantly associated with the NSCLC overall survival, with a combined hazards ratio (HR) of 0.83 [95% confidence interval (CI) = 0.74-0.93 and P = 0.0009] and 1.18 (95% CI = 1.06-1.31) and P = 0.002], respectively. However, further expression quantitative trait loci (eQTL) analysis showed no evidence for correlations between the two SNPs and mRNA expression levels of corresponding genes. These results indicated that genetic variants in the NLRP3 imflammasome pathway gene-sets might be predictors of NSCLC survival, but the molecular mechanisms underlying the observed associations warrant further investigations.

Novel genetic variants in genes of the Fc gamma receptor-mediated phagocytosis pathway predict non-small cell lung cancer survival.

BACKGROUND: Both antibody-dependent cellular cytotoxicity and phagocytosis activate innate immunity, and the Fc gamma receptor (FCGR)-mediated phagocytosis is an integral part of the process. We assessed associations between single-nucleotide polymorphisms (SNPs) in FCGR-related genes and survival of patients with non-small cell lung cancer (NSCLC). METHODS: We evaluated associations between 24,734 (SNPs) in 97 FCGR-related genes and survival of 1,185 patients with NSCLC using a published genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial and validated the results in another independent dataset of 894 NSCLC patients. RESULTS: In the single-locus analysis with Bayesian false discovery probability (BFDP) for multiple testing correction, we found 1,084 SNPs to be significantly associated overall survival (OS) (P<0.050 and BFDP ≤0.80), of which two independent SNPs (PLCG2 rs9673682 T>G and PLPP1 rs115613985 T>A) were further validated in another GWAS dataset of 894 patients from the Harvard Lung Cancer Susceptibility (HLCS) Study, with combined allelic hazards ratios for OS of 0.87 [95% confidence interval (CI): 0.81-0.94 and P=5.90×10-4] and 1.18 (95% CI: 1.08-1.29 and 1.32×10-4, respectively). Expression quantitative trait loci analysis showed that the rs9673682 G allele was significantly correlated with increased mRNA expression levels of PLCG2 in 373 transformed lymphoblastoid cell-lines (P=7.20×10-5). Additional evidence from differential expression analysis further supported a tumor-suppressive effect of PLCG2 on OS of patients with lung cancer, with lower mRNA expression levels in both lung squamous carcinoma and adenocarcinoma than in adjacent normal tissues. CONCLUSIONS: Genetic variants in PLCG2 of the FCGR-mediated phagocytosis pathway may be promising predictors of NSCLC survival, possibly through modulating gene expression, but additional investigation of the molecular mechanisms of PLPP1 rs115613985 is warranted.

Genetic variants of the peroxisome proliferator-activated receptor (PPAR) signaling pathway genes and risk of pancreatic cancer.

Because the peroxisome proliferator-activated receptor (PPAR) signaling pathway is involved in development and progression of pancreatic cancer, we investigated associations between genetic variants of the PPAR pathway genes and pancreatic cancer risk by using three published genome-wide association study datasets including 8477 cases and 6946 controls of European ancestry. Expression quantitative trait loci (eQTL) analysis was also performed for correlations between genotypes of the identified genetic variants and messenger RNA (mRNA) expression levels of their genes by using available databases of the 1000 Genomes, TCGA, and GTEx projects. In the single-locus logistic regression analysis, we identified 1141 out of 17 532 significant single-nucleotide polymorphisms (SNPs) in 112 PPAR pathway genes. Further multivariate logistic regression analysis identified three independent, potentially functional loci (rs12947620 in MED1, rs11079651 in PRKCA, and rs34367566 in PRKCB) for pancreatic cancer risk (odds ratio [OR] = 1.11, 95% confidence interval [CI], [1.06-1.17], P = 5.46 × 10-5 ; OR = 1.10, 95% CI, [1.04-1.15], P = 1.99 × 10-4 ; and OR = 1.09, 95% CI, [1.04-1.14], P = 3.16 × 10-4 , respectively) among 65 SNPs that passed multiple comparison correction by false discovery rate (< 0.2). When risk genotypes of these three SNPs were combined, carriers with 2 to 3 unfavorable genotypes (NUGs) had a higher risk of pancreatic cancer than those with 0 to 1 NUGs. The eQTL analysis showed that rs34367566 A>AG was associated with decreased expression levels of PRKCB mRNA in 373 lymphoblastoid cell lines. Our findings indicate that genetic variants of the PPAR pathway genes, particularly MED1, PRKCA, and PRKCB, may contribute to susceptibility to pancreatic cancer.

Genetic variants in PDSS1 and SLC16A6 of the ketone body metabolic pathway predict cutaneous melanoma-specific survival.

A few single-nucleotide polymorphisms (SNPs) have been identified to be associated with cutaneous melanoma (CM) survival through genome-wide association studies, but stringent multiple testing corrections required for the hypothesis-free testing may have masked some true associations. Using a hypothesis-driven analysis approach, we sought to evaluate associations between SNPs in ketone body metabolic pathway genes and CM survival. We comprehensively assessed associations between 4196 (538 genotyped and 3658 imputed) common SNPs in 44 ketone body metabolic pathway genes and CM survival, using a dataset of 858 patients of a case-control study from The University of Texas M.D. Anderson Cancer Center as the discovery set and another dataset of 409 patients from the Nurses' Health Study and the Health Professionals Follow-up Study as the replication set. There were 95/858 (11.1%) and 48/409 (11.7%) patients who died of CM, respectively. We identified two independent SNPs (ie, PDSS1 rs12254548 G>C and SLC16A6 rs71387392 G>A) that were associated with CM survival, with allelic hazards ratios of 0.58 (95% confidence interval [CI] = 0.44-0.76, P = 9.00 × 10-5 ) and 1.98 (95% CI = 1.34-2.94, P = 6.30 × 10-4 ), respectively. Additionally, associations between genotypes of the SNPs and messenger RNA expression levels of their corresponding genes support the biologic plausibility of a role for these two variants in CM tumor progression and survival. Once validated by other larger studies, PDSS1 rs12254548 and SLC16A6 rs71387392 may be valuable biomarkers for CM survival.

Novel genetic variants in HDAC2 and PPARGC1A of the CREB-binding protein pathway predict survival of non-small-cell lung cancer.

The CREB-binding protein (CBP) pathway plays an important role in transcription and activity of acetyltransferase that acetylates lysine residues of histones and nonhistone proteins. In the present study, we hypothesized that genetic variants in the CBP pathway genes played a role in survival of non-small-cell lung cancer (NSCLC). We tested this hypothesis using the genotyping data from the genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. In the single-locus analysis, we evaluated associations between 13 176 (1107 genotyped and 12 069 imputed) single-nucleotide polymorphisms (SNPs) in 72 genes and survival of 1185 patients with NSCLC. The identified 106 significant SNPs in the discovery were further validated in additional genotyping data from another GWAS dataset of 984 patients with NSCLC in the Harvard Lung Cancer Susceptibility Study. The combined results of two datasets showed that two independent, potentially functional SNPs (i.e., HDAC2 rs13213007G>A and PPARGC1A rs60571065T>A) were significantly associated with NSCLC overall survival, with a combined hazards ratio (HR) of 1.26 (95% confidence interval (CI), 1.09-1.45; P = .002) and 1.23 (1.04-1.47; P = .017), respectively. Furthermore, we performed an expression quantitative trait loci analysis and found that the survival-associated HDAC2 rs13213007A allele (GA+AA), but not PPARGC1A rs60571065A allele (TA+AA), was significantly associated with increased messenger RNA expression levels of HDAC2 in 373 lymphoblastoid cell lines. These results indicate that the HDAC2 rs13213007A allele is a potential predictor of NSCLC survival, likely by altering the HDAC2 expression.

Genetic variants in the liver kinase B1-AMP-activated protein kinase pathway genes and pancreatic cancer risk.

The liver kinase B1-AMP-activated protein kinase (LKB1-AMPK) pathway has been identified as a new target for cancer therapy, because it controls the glucose and lipid metabolism in response to alterations in nutrients and intracellular energy levels. In the present study, we aimed to identify genetic variants of the LKB1-AMPK pathway genes and their associations with pancreatic cancer (PanC) risk using 15 418 participants of European ancestry from two previously published PanC genome-wide association studies. We found that six novel tagging single-nucleotide polymorphisms (SNPs) (i.e, MAP2 rs35075084 T > deletion, PRKAG2 rs2727572 C > T and rs34852782 A > deletion, TP53 rs9895829 A > G, and RPTOR rs62068300 G > A and rs3751936 G > C) were significantly associated with an increased PanC risk. The multivariate logistic regression model incorporating the number of unfavorable genotypes (NUGs) with adjustment for age and sex showed that carriers with five to six NUGs had an increased PanC risk (odds ratio = 1.24, 95% confidence interval = 1.16-1.32 and P < 0.0001), compared to those with zero to four NUGs. Subsequent expression quantitative trait loci (eQTL) analysis further revealed that these SNPs were associated with significantly altered mRNA expression levels either in 373 normal lymphoblastoid cell lines (TP53 SNP rs9895829, P < 0.05) or in whole blood cells of 369 normal donors from the genotype-tissue expression project (GTEx) database [RPTOR SNP rs60268947 and rs28434589, both in high linkage disequilibrium (r2 > 0.9) withRPTOR rs62068300, P < 0.001]. Collectively, our findings suggest that these novel SNPs in the LKB1-AMPK pathway genes may modify susceptibility to PanC, possibly by influencing gene expression.

Genetic variants of genes in the NER pathway associated with risk of breast cancer: A large-scale analysis of 14 published GWAS datasets in the DRIVE study.

A recent hypothesis-free pathway-level analysis of genome-wide association study (GWAS) datasets suggested that the overall genetic variation measured by single nucleotide polymorphisms (SNPs) in the nucleotide excision repair (NER) pathway genes was associated with breast cancer (BC) risk, but no detailed SNP information was provided. To substantiate this finding, we performed a larger meta-analysis of 14 previously published GWAS datasets in the Discovery, Biology and Risk of Inherited Variants in Breast Cancer (DRIVE) study with 53,107 subjects of European descent. Using a hypothesis-driven approach, we selected 138 candidate genes from the NER pathway using the "Molecular Signatures Database (MsigDB)" and "PathCards". All SNPs were imputed using IMPUTE2 with the 1000 Genomes Project Phase 3. Logistic regression was used to estimate BC risk, and pooled ORs for each SNP were obtained from the meta-analysis using the false discovery rate for multiple test correction. RegulomeDB, HaploReg, SNPinfo and expression quantitative trait loci (eQTL) analysis were used to assess the SNP functionality. We identified four independent SNPs associated with BC risk, BIVM-ERCC5 rs1323697_C (OR = 1.06, 95% CI = 1.03-1.10), GTF2H4 rs1264308_T (OR = 0.93, 95% CI = 0.89-0.97), COPS2 rs141308737_C deletion (OR = 1.06, 95% CI = 1.03-1.09) and ELL rs1469412_C (OR = 0.93, 95% CI = 0.90-0.96). Their combined genetic score was also associated with BC risk (OR = 1.12, 95% CI = 1.08-1.16, ptrend < 0.0001). The eQTL analysis revealed that BIVM-ERCC5 rs1323697 C and ELL rs1469412 C alleles were correlated with increased mRNA expression levels of their genes in 373 lymphoblastoid cell lines (p = 0.022 and 2.67 × 10-22 , respectively). These SNPs might have roles in the BC etiology, likely through modulating their corresponding gene expression.

Functional variant of MTOR rs2536 and survival of Chinese gastric cancer patients.

We previously reported that some single nucleotide polymorphisms (SNPs) of candidate genes involved in the MTOR complex1 (MTORC1) were associated with risk of gastric cancer (GCa). In the present study, we further evaluated associations of eight potentially functional SNPs of MTOR, MLST8 and RPTOR with survival of 1002 GCa patients and also investigated molecular mechanisms underlying such associations. Specifically, we found that the MTOR rs2536 C allele at the microRNA binding site was independently associated with a 26% reduction of death risk (HR = 0.74, 95% CI = 0.57-0.96, p = 0.022). The results remained noteworthy with a prior false positive probability of 0.1. Genotype-phenotype correlation analysis in 144 patients' adjacent normal gastric tissue samples revealed that the MTOR expression levels were lower in rs2536 TC/CC carriers than that in wild-type TT carriers (p = 0.043). Dual luciferase assays revealed that the rs2536 C allele had a higher binding affinity to microRNA-150, leading to a decreased transcriptional activity of MTOR, compared to the rs2536 T allele. Further functional analysis revealed that MTOR knockdown by small interference RNA impaired proliferation, migration, and invasion ability in GCa cell lines. In conclusion, The MTOR rs2536 T > C change may be a biomarker for survival of Chinese GCa patients, likely by modulating microRNA-induced gene expression silencing. Additional studies are needed to validate our findings.

Potentially functional genetic variants in the complement-related immunity gene-set are associated with non-small cell lung cancer survival.

The complement system plays an important role in the innate and adaptive immunity, complement components mediate tumor cytolysis of antibody-based immunotherapy, and complement activation in the tumor microenvironment may promote tumor progression or inhibition, depending on the mechanism of action. In the present study, we conducted a two-phase analysis of two independently published genome-wide association studies (GWASs) for associations between genetic variants in a complement-related immunity gene-set and overall survival of non-small cell lung cancer (NSCLC). The GWAS dataset from Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial was used as the discovery, and multivariate Cox proportional hazards regression with false-positive report probability for multiple test corrections were performed to evaluate associations between 14,699 single-nucleotide polymorphisms (SNPs) in 111 genes and survival of 1,185 NSCLC patients. The identified significant SNPs in a single-locus analysis were further validated with 984 NSCLC patients in the GWAS dataset from the Harvard Lung Cancer Susceptibility (HLCS) Study. The results showed that two independent, potentially functional SNPs in two genes (VWF rs73049469 and ITGB2 rs3788142) were significantly associated with NSCLC survival, with a combined hazards ratio (HR) of 1.22 [95% confidence interval (CI) = 1.07-1.40, P = 0.002] and 1.16 (1.07-1.27, 6.45 × 10-4 ), respectively. Finally, we performed expression quantitative trait loci (eQTL) analysis and found that survival-associated genotypes of VWF rs73049469 were also significantly associated with mRNA expression levels of the gene. These results indicated that genetic variants of the complement-related immunity genes might be predictors of NSCLC survival, particularly for the short-term survival, possibly by modulating the expression of genes involved in the host immunity.

An ERCC4 regulatory variant predicts grade-3 or -4 toxicities in patients with advanced non-small cell lung cancer treated by platinum-based therapy.

Platinum-based chemotherapy (PBC) in combination with the 3rd generation drugs is the first-line treatment for patients with advanced non-small cell lung cancer (NSCLC); however, the efficacy is severely hampered by grade 3-4 toxicities. Nucleotide excision repair (NER) pathway is the main mechanism of removing platinum-induced DNA adducts that contribute to the toxicity and outcome of PBC. We analyzed data from 710 Chinese NSCLC patients treated with PBC and assessed the associations of 25 potentially functional single nucleotide polymorphisms (SNPs) in nine NER core genes with overall, gastrointestinal and hematologic toxicities. Through a two-phase study, we found that ERCC4 rs1799798 was significantly associated with overall and gastrointestinal toxicities [all patients: GA/AA vs. GG, odds ratio (OR)adj =1.61 and 2.35, 95% confidence interval (CI)=1.11-2.33 and 1.25-4.41, and Padj =0.012 and 0.008, respectively]. Our prediction model for the overall toxicity incorporating rs1799798 demonstrated a significant increase in the area under the curve (AUC) value, compared to that for clinical factors only (all patients: AUC = 0.61 vs. 0.59, 95% CI = 0.57-0.65 vs. 0.55-0.63, P = 0.010). Furthermore, the ERCC4 rs1799798 A allele was associated with lower ERCC4 mRNA expression levels according to the expression quantitative trait loci (eQTL) analysis. Our study provided some new clue in future development of biomarkers for assessing toxicity and outcomes of platinum drugs in lung cancer treatment.

Anexelekto (AXL) Increases Resistance to EGFR-TKI and Activation of AKT and ERK1/2 in Non-Small Cell Lung Cancer Cells.

Recently, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have revolutionized non-small cell lung cancer (NSCLC) treatment. However, resistance remains a major obstacle. Anexelekto (AXL) is a member of receptor tyrosine kinases (RTKs) and shares the same downstream signaling pathways with EGFR, such as PI3K/AKT and MAPK/ERK. AXL overexpression in resistant tumors has been implicated in many previous studies in vitro and in vivo. In this study, we further examined whether expression of AXL and its downstream targets increased in gefitinib-resistant PC9 cells (PC9GR). In addition, we hypothesize that knocking down AXL in PC9GR and overexpressing AXL in PC9 using genetic tools can restore and decrease the sensitivity to gefitinib, respectively. We found that silencing AXL could sensitize the resistance to gefitinib, and the downstream pathways were significantly inhibited. Interestingly, we also discovered that increased AXL expression did promote the resistance, and its downstream targets were activated accordingly. Then 69 NSCLC patients who harbored EGFR mutation were recruited to analyze the expression of AXL and the association between AXL expression and clinical characteristics. We found that 5 of the 69 patients were AXL positive (about 7%), and AXL was related to tumor differentiation and tumor size. In this study, we concluded that the molecular mechanisms of AXL mediated resistance involved in the increased activity of the PI3K/AKT and MAPK/ERK1/2 pathways, and AXL overexpression could promote resistance, but it can be weakened when AXL expression is silenced.

Treatment and prognostic analysis of patients with leptomeningeal metastases from non-small cell lung cancer.

BACKGROUND: Leptomeningeal metastases (LM) from non-small cell lung cancer (NSCLC) are associated with poor prognosis and optimal treatment for this subgroup of NSCLC patients is controversial. The purpose of this study is to evaluate treatment options and prognostic factors of NSCLC patients with LM. METHODS: We retrospectively analyzed data of 108 patients who had been diagnosed with LM from NSCLC between May 2006 and August 2013. RESULTS: The median survival time (MST) of the 108 patients was 5.3 months, and the one-year survival rate was 23.7%. Forty-nine patients received whole brain radiotherapy (WBRT) and the MST of patients who received WBRT and those who did not were 6.4 and 4.3 months, respectively. Forty-two patients were treated with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) after being diagnosed with LM. These patients had prolonged survival (11.1 vs. 4.4 months). Patients who received concomitant WBRT and EGFR-TKIs had the longest MST (12.3 months). Eastern Cooperative Oncology Group performance status, whether patients received WBRT, and/or EGFR-TKIs were independent prognostic factors for patients with LM from NSCLC. CONCLUSION: WBRT, EGFR-TKIs or combined therapy, could lead to better clinical outcomes for NSCLC patients with LM. EGFR-TKIs plus WBRT has the potential to be the standard strategy for LM in NSCLC patients.

Enforced expression of RASAL1 suppresses cell proliferation and the transformation ability of gastric cancer cells.

RAS protein activator like 1 (RASAL1) is a member of the RAS GTPase-activating protein (GAP) family, and it is an important molecule in the regulation of RAS activation. In the present study, we investigated the role of RASAL1 in gastric carcinogenesis. Decreased expression pattern of RASAL1 in gastric cancer tissues and cell lines was found in protein and RNA levels, although there was no statistically significant relationship between RASAL1 and clinicopathological features. Restored expression of RASAL1 induced by DNA methylation inhibitor 5-aza-2'-deoxycytidine (5'-AZA) and HDAC inhibitor trichostatin A (TSA) implied that RASAL1 expression is regulated by epigenetic mechanisms. The biological role of RASAL1 in gastric carcinogenesis was determined by in vitro tumorigenicity assays. Overexpression of RASAL1 showed suppression of cell proliferation due to cell apoptosis. Subsequently, enforced expression of RASAL1 repressed significantly the gastric cancer cell transformation ability. These findings demonstrated that decreased RASAL1 expression is a characteristic of gastric cancer and regulated by epigenetic mechanisms. RASAL1 may be a functional tumor suppressor involved in gastric cancer. This study provides novel insights into the biological role of RASAL1 in gastric carcinogenesis.