Hua Bai

Quantification of mutant alleles in circulating tumor DNA can predict survival in lung cancer

Purpose We aimed to investigate the feasibility of droplet digital PCR (ddPCR) for the quantitative and dynamic detection of EGFR mutations and next generation sequencing (NGS) for screening EGFR-tyrosine kinase inhibitors (EGFR-TKIs) resistance-relevant mutations in circulating tumor DNA (ctDNA) from advanced lung adenocarcinoma (ADC) patients. Results Detection limit of EGFR mutation in ctDNA by ddPCR was 0.04%. Taking the EGFR mutation in tumor tissue as the golden standard, the concordance of EGFR mutations detected in ctDNA was 74% (54/73). Patients with EGFR mutation in ctDNA (n = 54) superior progression-free survival (PFS, median, 12.6 vs. 6.7 months, P < 0.001) and overall survival (OS, median, 35.6 vs. 23.8 months, P = 0.028) compared to those with EGFR wild type in ctDNA (n = 19). Patients with high EGFR-mutated abundance in ctDNA (> 5.15%) showed better PFS compared to those with low EGFR mutated abundance (≤ 5.15%) (PFS, median, 15.4 vs. 11.1 months, P = 0.021). NGS results showed that 66.6% (8/12) total mutational copy number were elevated and 76.5% (26/34) mutual mutation frequency increased after disease progression. Methods Seventy-three advanced ADC patients with tumor tissues carrying EGFR mutations and their matched pre- and post-EGFR-TKIs plasma samples were enrolled in this study. Absolute quantities of plasma EGFR mutant and wild-type alleles were measured by ddPCR. Multi-genes testing was performed using NGS in 12 patients. Conclusions Dynamic and quantitative analysis of EGFR mutation in ctDNA could guide personalized therapy for advanced ADC. NGS shows good performance in multiple genes testing especially novel and uncommon genes.

Comprehensive Analysis of the Discordance of EGFR Mutation Status between Tumor Tissues and Matched Circulating Tumor DNA in Advanced Non-Small Cell Lung Cancer.

Introduction: This study aimed to address the underlying reasons for and clinical significance of the discordant EGFR mutation (EGFRm) status between tumor tissue (TT) and circulating tumor DNA (ctDNA). Methods: Three groups of EGFR tyrosine kinase inhibitor (EGFR TKI)‐treated patients whose EGFRm status was determined by the amplification refractory mutation system (ARMS) were included (group A, TT‐positive/ctDNA‐positive EGFRm status; group B, TT‐negative/ctDNA‐positive EGFRm status; and group C, TT‐positive/ctDNA‐negative EGFRm status). Patients with discordant EGFRm status were reevaluated by droplet digital polymerase chain reaction (ddPCR) and next‐generation sequencing. Meanwhile, surgical tumor specimens were microdissected for EGFRm detection by ddPCR. Results: Of the 2463 patients with matched TT and ctDNA specimens, 1017 patients carried EGFRm in TT and/or ctDNA by the ARMS. Of these 1017 patients, 472 received EGFR TKIs, including 264, 28, and 180 in groups A, B, and C, respectively. The median progression‐free survivals of those receiving EGFR TKIs across the three groups were similar (p = 0.062). Through ddPCR and next‐generation sequencing of biopsy specimens (n = 22) and microdissected surgical specimens (n = 5), 27 patients in group B were identified as harboring EGFRm. After reevaluation by ddPCR, 64 patients in group C tested positive for EGFRm in their ctDNA. ctDNA as a screen for EGFRm then tissues as supplement (ctDNA→TT pattern) had similar detection efficiency and saved about 30% of TT compared with TT for initial EGFRm detection followed by ctDNA (TT→ctDNA pattern). Conclusions: Intratumor heterogeneity and the relatively low sensitivity of the ARMS contributed to discordant EGFRm status between TT specimens and ctDNA. The ctDNA→TT pattern might be a rational clinical procedure for EGFRm determination.

Potential Resistance Mechanisms Revealed by Targeted Sequencing from Lung Adenocarcinoma Patients with Primary Resistance to Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitors (TKIs)

Introduction EGFR tyrosine kinase inhibitors (TKIs) have greatly improved the prognosis of lung adenocarcinoma. However, approximately 5% to 10% of patients with lung adenocarcinoma with EGFR sensitive mutations have primary resistance to EGFR TKI treatment. The underlying mechanism is unknown. Methods This study used next‐generation sequencing to explore the mechanisms of primary resistance by analyzing 11 patients with primary resistance and 11 patients sensitive to EGFR TKIs. Next‐generation targeted sequencing was performed on the Illumina X platform for 483 cancer‐related genes. EGFR mutation was initially detected using the amplification refractory mutation system. Results Potential primary resistance mechanisms were revealed by mutations unique to the EGFR TKI resistance group. Among the 11 resistant patients, 45% (five of 11) harbored a known resistance mechanism, such as MNNG HOS Transforming gene (MET) amplification de novo T790M mutation or overlapping T790M and phosphatase and tensin homolog gene (PTEN) loss and erb‐b2 receptor tyrosine kinase 2 gene (ERBB2) amplification. In six of 11 resistant cases (54%), potential novel mutations that might lead to drug resistance were identified (including transforming growth factor beta receptor 1 gene [TGFBR1] mutation and/or EGFR structural rearrangement mechanistic target of rapamycin kinase gene [MTOR] mutation, transmembrane protease, serine 2 gene [TMPRSS2] fusion gene, and v‐myc avian myelocytomatosis viral oncogene homolog gene [MYC] amplification). By analyzing somatic mutation patterns, the frequency of C:G→T:A transitions in the patients with primary resistance was significantly higher than that in sensitive group and occurred more frequently in the non‐CpG region (Cp(A/C/T)→T). Conclusion The mechanisms of primary resistance to EGFR TKIs may be highly heterogeneous. Mutations in EGFR and its downstream pathway, as well as mutations that affect tumor cell function, are related to primary resistance. Somatic single‐nucleotide mutation patterns might be associated with primary resistance to EGFR TKIs.

Correlation among genetic variations of c-MET in Chinese patients with non-small cell lung cancer

Background The purpose of our research was to determine the correlation of amplification, protein expression and somatic mutation of c-MET in IIIb-IV stage NSCLC (Non-small cell lung cancer). We also explored correlation of c-MET variation with clinical outcome. Results c-MET expression was observed in 28.6% (56/196) cases, and among those 13.8% (27/196) were shown to be FISH positive. Only 2.67% patients in this study carried the c-MET mutation. Cases with c-MET FISH positive were all IHC positive ,but in IHC positive cases, only half were FISH positive. Among patients with IHC2+ staining, 35.5% was FISH positive, while cases with IHC3+ staining,64% was FISH positive. Both protein expression and copy number of c-MET did not significantly correlate with clinical prognosis in these patients treated with EGFR-TKIs. Conclusions IHC could be used as a preliminary screening method for c-MET copy number amplification and should be confirmed by FISH only in IHC positive case which facilitate selection of ALK or MET inhibitor therapy. Methods c-MET gene copy number, protein expression and somatic mutation for exon 14 were detected by fluorescent- In-Situ-Hybridization (FISH), Immunohistochemistry (IHC), and Denaturing-High-Performance-Liquid-Chromatography (DHPLC), respectively, in 196 NSCLC patients. The relationship between c-MET abnormalities and clinical outcome of targeted therapy was analyzed by McNemars test.

Prediction of chemotherapeutic efficacy in non-small cell lung cancer by serum metabolomic profiling

Purpose: No validated biomarkers that could identify the subset of patients with lung adenocarcinoma who might benefit from chemotherapy have yet been well established. This study aimed to explore potential biomarker model predictive of efficacy and survival outcomes after first-line pemetrexed plus platinum doublet based on metabolomics profiling. Experimental Design: In total, 354 consecutive eligible patients were assigned to receive first-line chemotherapy of pemetrexed in combination with either cisplatin or carboplatin. Prospectively collected serum samples before initial treatment were utilized to perform metabolomics profiling analyses under the application of LC/MS-MS. Binary logistic regression analysis was carried out to establish discrimination models. Results: There were 251 cases randomly sorted into discovery set, the rest of 103 cases into validation set. Seven metabolites including hypotaurine, uridine, dodecanoylcarnitine, choline, dimethylglycine, niacinamide, and l-palmitoylcarnitine were identified associated with chemo response. On the basis of the seven-metabolite panel, a discriminant model according to logistic regression values g(z) was established with the receiver operating characteristic curve (AUC) of 0.912 (Discovery set) and 0.909 (Validation set) in differentiating progressive disease (PD) groups from disease control (DC) groups. The median progression-free survival (PFS) after chemotherapy in patients with g(z) ≤0.155 was significantly longer than that in those with g(z) > 0.155 (10.3 vs.4.5 months, P < 0.001). Conclusions: This study developed an effective and convenient discriminant model that can accurately predict the efficacy and survival outcomes of pemetrexed plus platinum doublet chemotherapy prior to treatment delivery. Clin Cancer Res; 24(9); 2100–9. ©2018 AACR.

Analysis of topoisomerase I expression and identification of predictive markers for efficacy of topotecan chemotherapy in small cell lung cancer: Topoisomerase I in SCLC

We evaluated topoisomerase I (TOPO1) expression in patients with small cell lung cancer (SCLC) and identified predictive factors for the efficacy of second‐line topotecan chemotherapy.

Impact of PD-L1, transforming growth factor-β expression and tumor-infiltrating CD8+ T cells on clinical outcome of patients with advanced thymic epithelial tumors: PD-L1, TGF-β, and CD8+ TILs in TETs

Advanced thymic epithelial tumors (TETs) are indolent and poorly responsive to chemotherapy. PD‐1/PD‐L1 inhibitors have shown remarkable clinical benefit in several cancers; however, many immunomodulatory molecules have been identified that affect the immune response. This study examined the progonostic roles of PD‐L1, transforming growth factor‐β (TGF‐β), and CD8+ tumor‐infiltrating lymphocytes (CD8+ TILs) in patients with TETs.

Mechanistic Exploration of Cancer Stem Cell Marker Voltage-Dependent Calcium Channel α2δ1 Subunit-mediated Chemotherapy Resistance in Small-Cell Lung Cancer

Purpose: Chemoresistance in small-cell lung cancer (SCLC) is reportedly attributed to the existence of resistant cancer stem cells (CSC). Studies involving CSC-specific markers and related mechanisms in SCLC remain limited. This study explored the role of the voltage-dependent calcium channel α2δ1 subunit as a CSC marker in chemoresistance of SCLC, and explored the potential mechanisms of α2δ1-mediated chemoresistance and strategies of overcoming the resistance. Experimental Design: α2δ1-positive cells were identified and isolated from SCLC cell lines and patient-derived xenograft (PDX) models, and CSC-like properties were subsequently verified. Transcriptome sequencing and Western blotting were carried out to identify pathways involved in α2δ1-mediated chemoresistance in SCLC. In addition, possible interventions to overcome α2δ1-mediated chemoresistance were examined. Results: Different proportions of α2δ1+ cells were identified in SCLC cell lines and PDX models. α2δ1+ cells exhibited CSC-like properties (self-renewal, tumorigenic, differentiation potential, and high expression of genes related to CSCs and drug resistance). Chemotherapy induced the enrichment of α2δ1+ cells instead of CD133+ cells in PDXs, and an increased proportion of α2δ1+ cells corresponded to increased chemoresistance. Activation and overexpression of ERK in the α2δ1-positive H1048 cell line was identified at the protein level. mAb 1B50-1 was observed to improve the efficacy of chemotherapy and delay relapse as maintenance therapy in PDX models. Conclusions: SCLC cells expressing α2δ1 demonstrated CSC-like properties, and may contribute to chemoresistance. ERK may play a key role in α2δ1-mediated chemoresistance. mAb 1B50-1 may serve as a potential anti-SCLC drug. Clin Cancer Res; 24(9); 2148–58. ©2018 AACR.