Haichuan Hu

RET Fusions Define a Unique Molecular and Clinicopathologic Subtype of Non–Small-Cell Lung Cancer

PURPOSE The RET fusion gene has been recently described in a subset of non-small-cell lung cancers (NSCLCs). Because we have limited knowledge about these tumors, this study was aimed at determining the clinicopathologic characteristics of patients with NSCLC harboring the RET fusion gene. PATIENTS AND METHODS We examined the RET fusion gene in 936 patients with surgically resected NSCLC using a reverse transcriptase polymerase chain reaction (PCR) plus quantitative real-time PCR strategy, with validation using immunohistochemical and fluorescent in situ hybridization assays. A subset of 633 lung adenocarcinomas was also studied for EGFR, KRAS, HER2, and BRAF mutations, as well as ALK rearrangements. Patient characteristics, including age, sex, smoking history, stage, grade, International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification of subtypes of lung adenocarcinoma, and relapse-free survival, were collected. RESULTS Of 936 patients with NSCLC, the RET fusion gene was exclusively detected in 13 patients (11 of 633 patients with adenocarcinomas and two of 24 patients with adenosquamous cell carcinomas). Of the 13 patients, nine patients had KIF5B-RET, three patients had CCDC6-RET, and one patient had a novel NCOA4-RET fusion. Patients with lung adenocarcinomas with RET fusion gene had more poorly differentiated tumors (63.6%; P = .029 for RET v ALK, P = .007 for RET v EGFR), with a tendency to be younger (≤ 60 years; 72.7%) and never-smokers (81.8%) and to have solid subtype (63.6%) and a smaller tumor (≤ 3 cm) with N2 disease (54.4%). The median relapse-free survival was 20.9 months. CONCLUSION RET fusion occurs in 1.4% of NSCLCs and 1.7% of lung adenocarcinomas and has identifiable clinicopathologic characteristics, warranting further clinical consideration and targeted therapy investigation.

Tumor cells can follow distinct evolutionary paths to become resistant to epidermal growth factor receptor inhibition

Although mechanisms of acquired resistance of epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancers to EGFR inhibitors have been identified, little is known about how resistant clones evolve during drug therapy. Here we observe that acquired resistance caused by the EGFRT790M gatekeeper mutation can occur either by selection of pre-existing EGFRT790M-positive clones or via genetic evolution of initially EGFRT790M-negative drug-tolerant cells. The path to resistance impacts the biology of the resistant clone, as those that evolved from drug-tolerant cells had a diminished apoptotic response to third-generation EGFR inhibitors that target EGFRT790M; treatment with navitoclax, an inhibitor of the anti-apoptotic factors BCL-xL and BCL-2 restored sensitivity. We corroborated these findings using cultures derived directly from EGFR inhibitor–resistant patient tumors. These findings provide evidence that clinically relevant drug-resistant cancer cells can both pre-exist and evolve from drug-tolerant cells, and they point to therapeutic opportunities to prevent or overcome resistance in the clinic.

The allelic context of the C797S mutation acquired upon treatment with third generation EGFR inhibitors impacts sensitivity to subsequent treatment strategies

Purpose: A secondary EGFR mutation, T790M, is the most common resistance mechanism in EGFR-mutant adenocarcinomas that have progressed on erlotinib. Third-generation EGFR inhibitors capable of inhibiting mutant EGFR with T790M produce responses in nearly two thirds of patients. However, acquired resistance mechanisms in patients treated with these drugs are yet to be described. Experimental Design: To study acquired resistance to third-generation EGFR inhibitors, T790M-positive cells derived from an erlotinib-resistant cancer were made resistant to a third-generation TKI and then characterized using cell and molecular analyses. Results: Cells resistant to a third-generation TKI acquired an additional EGFR mutation, C797S, which prevented suppression of EGFR. Our results demonstrate that the allelic context in which C797S was acquired may predict responsiveness to alternative treatments. If the C797S and T790M mutations are in trans, cells will be resistant to third-generation EGFR TKIs, but will be sensitive to a combination of first- and third-generation TKIs. If the mutations are in cis, no EGFR TKIs alone or in combination can suppress activity. If C797S develops in cells wild-type for T790 (when third-generation TKIs are administered in the first-line setting), the cells are resistant to third-generation TKIs, but retain sensitivity to first-generation TKIs. Conclusions: Mutation of C797S in EGFR is a novel mechanism of acquired resistance to third-generation TKIs. The context in which the C797S develops with respect to the other EGFR alleles affects the efficacy of subsequent treatments. Clin Cancer Res; 21(17); 3924–33. ©2015 AACR. See related commentary by Ayeni et al., p. 3818

Protein expression of programmed death 1 ligand 1 and ligand 2 independently predict poor prognosis in surgically resected lung adenocarcinoma

Background The clinicopathologic characteristics of tumors expressing programmed death (PD-1) ligands (PD-Ls) PD-L1 or PD-L2 and their associations with common driver mutations in lung adenocarcinoma are not clearly defined, despite the progression of anti-PD-1/PD-L1 immunotherapy. Methods PD-L1 and PD-L2 expression was measured by immunohistochemistry in 143 surgically resected lung adenocarcinomas and was correlated with clinical variables, histologic subtypes, and the mutational status of EGFR, KRAS, HER2, and ALK. Results Positive PD-L1 expression was significantly associated with more advanced T status, N status, and pathologic stage. Histologically, lung adenocarcinomas with positive PD-L1 staining were less likely to be adenocarcinoma in situ or minimally invasive adenocarcinoma and more likely to have solid predominant subtype. Both PD-L1 expression (odds ratio =1.984, 95% confidence interval =1.010–3.894; P=0.047) and PD-L2 expression (odds ratio =2.328, 95% confidence interval =1.201–4.512; P=0.012) were independent predictors of poor overall survival. When the combined PD-L expression and pathologic stage were used together to predict overall survival, the concordance index increased to 0.763, and the Akaike information criteria value decreased to 356.08. Conclusion We defined the clinicopathologic features of lung adenocarcinomas with high expression of PD-L1 and PD-L2. We further demonstrated the role of PD-L expression as a useful prognostic marker for lung adenocarcinoma.

Frequency of Driver Mutations in Lung Adenocarcinoma from Female Never-Smokers Varies with Histologic Subtypes and Age at Diagnosis

Purpose: Our previous study revealed that 90% [47 of 52; 95% confidence interval (CI), 0.79–0.96] of Chinese never-smokers with lung adenocarcinoma harbor known oncogenic driver mutations in just four genes EGFR, ALK, HER2, and KRAS. Here, we examined the status of known driver mutations specifically in female never-smokers with lung adenocarcinoma. Experimental Design: Tumors were genotyped for mutations in EGFR, KRAS, ALK, HER2, and BRAF. Data on age, stage, tumor differentiation, histologic subtypes, and molecular alterations were recorded from 349 resected lung adenocarcinomas from female never-smokers. We further compared the clinicopathologic parameters according to mutational status of these genes. Results: Two hundred and sixty-six (76.2%) tumors harbored EGFR mutations, 16 (4.6%) HER2 mutations, 15 (4.3%) EML4-ALK fusions, seven (2.0%) KRAS mutations, and two (0.6%) BRAF mutations. In univariate analysis, patients harboring EGFR mutations were significantly older (P < 0.001), whereas patients harboring HER2 mutations were significantly younger (P = 0.036). Higher prevalence of KRAS (P = 0.028) and HER2 (P = 0.021) mutations was found in invasive mucinous adenocarcinoma (IMA). The frequency of EGFR mutations was positively correlated with acinar predominant tumors (P = 0.002). Multivariate analysis revealed that older age at diagnosis (P = 0.013) and acinar predominant subtype (P = 0.005) were independent predictors of EGFR mutations. Independent predictors of HER2 mutations included younger age (P = 0.030) and IMA (P = 0.017). IMA (P = 0.006) and poor differentiation (P = 0.028) were independently associated with KRAS mutations. Conclusions: The frequency of driver mutations in never-smoking female lung adenocarcinoma varies with histologic subtypes and age at diagnosis. These data have implications for both clinical trial design and therapeutic strategies. Clin Cancer Res; 18(7); 1947–53. ©2012 AACR.

ALK, ROS1 and RET fusions in 1139 lung adenocarcinomas: A comprehensive study of common and fusion pattern-specific clinicopathologic, histologic and cytologic features

BACKGROUND To have a comprehensive investigation of the clinicopathologic, histologic and cytologic features of fusion-positive lung adenocarcinomas. METHODS Quantitative real-time reverse transcriptase PCR (qRT-PCR) and reverse transcriptase PCR (RT-PCR) were simultaneously performed to screen ALK, ROS1 and RET fusions in resected tumor samples from 1139 Chinese lung adenocarcinoma patients, with validation of positive results using fluorescent in situ hybridization. Clinicopathologic characteristics, predominant histologic subtype and cytomorphology were assessed in fusion-positive lung adenocarcinomas and compared to those harboring EGFR, KRAS, HER2 or BRAF mutations. RESULTS There were 58 (5.1%) ALK fusions, 11 (1.0%) ROS1 fusions and 15 (1.3%) RET fusions. Tumors with ROS1 fusions had significantly larger diameter than ROS1 fusion-negative tumors (P = 0.007), whereas all the 15 tumors harboring RET fusions were ≤ 3 cm in diameter (P = 0.001). The three fusion genes were all more prevalent in solid-predominant adenocarcinoma. Compared to fusion-negative lung adenocarcinomas, tumors harboring a fusion gene had significantly higher prevalence of extracellular mucin (P < 0.001), cribriform pattern (P < 0.001), signet ring cells (P < 0.001) and hepatoid cytology (P < 0.001). No significant difference in relapse-free survival (P = 0.147) and overall survival (P = 0.444) was observed between fusion-positive and fusion-negative patients. CONCLUSIONS This study showed fusion-positive lung adenocarcinomas had identifiable common and fusion-pattern specific clinicopathologic, histologic and cytologic features, offering implications for fusion genes screening.

PIK3CA mutations frequently coexist with EGFR/KRAS mutations in non-small cell lung cancer and suggest poor prognosis in EGFR/KRAS wildtype subgroup.

Purpose PIK3CA gene encoding a catalytic subunit of the phosphatidylinositol-3-kinase (PI3K) is mutated and/or amplified in various neoplasia, including lung cancer. Here we investigated PIK3CA gene alterations, the expression of core components of PI3K pathway, and evaluated their clinical importance in non-small cell lung cancer (NSCLC). Materials and methods Oncogenic mutations/rearrangements in PIK3CA, EGFR, KRAS, HER2, BRAF, AKT1 and ALK genes were detected in tumors from 1117 patients with NSCLC. PIK3CA gene copy number was examined by fluorescent in situ hybridization and the expression of PI3K p110 subunit alpha (PI3K p110α), p-Akt, mTOR, PTEN was determined by immunohistochemistry in PIK3CA mutant cases and 108 patients without PIK3CA mutation. Results PIK3CA mutation was found in 3.9% of squamous cell carcinoma and 2.7% of adenocarcinoma. Among 34 PIK3CA mutant cases, 17 tumors harbored concurrent EGFR mutations and 4 had KRAS mutations. PIK3CA mutation was significantly associated with high expression of PI3K p110α (p<0.0001), p-Akt (p = 0.024) and mTOR (p = 0.001), but not correlated with PIK3CA amplification (p = 0.463). Patients with single PIK3CA mutation had shorter overall survival than those with PIK3CA-EGFR/KRAS co-mutation or wildtype PIK3CA (p = 0.004). A significantly worse survival was also found in patients with PIK3CA mutations than those without PIK3CA mutations in the EGFR/KRAS wildtype subgroup (p = 0.043) Conclusions PIK3CA mutations frequently coexist with EGFR/KRAS mutations. The poor prognosis of patients with single PIK3CA mutation in NSCLC and the prognostic value of PIK3CA mutation in EGFR/KRAS wildtype subgroup suggest the distinct mutation status of PIK3CA gene should be determined for individual therapeutic strategies in NSCLC.

FGFR1/3 Tyrosine Kinase Fusions Define a Unique Molecular Subtype of Non-Small Cell Lung Cancer

Purpose: The fibroblast growth factor receptor (FGFR)-3 fusion genes have been recently demonstrated in a subset of non–small cell lung cancer (NSCLC). To aid in identification and treatment of these patients, we examined the frequency, clinicopathologic characteristics, and treatment outcomes of patients who had NSCLC with or without FGFR fusions. Experimental Design: Fourteen known FGFR fusion variants, including FGFR1, FGFR2, and FGFR3, were detected by RT-PCR and verified by direct sequencing in 1,328 patients with NSCLC. All patients were also analyzed for mutations in EGFR, KRAS, HER2, BRAF, ALK, RET, and ROS1. Clinical characteristics, including age, sex, smoking status, stage, subtypes of lung adenocarcinoma, relapse-free survival, and overall survival, were collected. Results: Of 1,328 tumors screened, two (0.2%) were BAG4-FGFR1 fusion and 15 (1.1%) were FGFR3-TACC3 fusion. Six of 1,016 patients with lung adenocarcinoma were FGFR3-TACC3 fusions and 11 of 312 lung squamous cell carcinoma harbored BAG4-FGFR1 or FGFR3-TACC3 fusions. Compared with the FGFR fusion-negative group, patients with FGFR fusions were more likely to be smokers (94.1%, 16 of 17 patients, P < 0.001), significantly associated with larger tumor (>3 cm; 88.2%, 15 of 17 patients, P < 0.001) and with a tendency to be more poorly differentiated (53.9%, nine of 17 patients, P = 0.095). Conclusions: FGFR fusions define a molecular subset of NSCLC with distinct clinical characteristics. FGFR is a druggable target and patients with FGFR fusions may benefit from FGFR-targeted therapy, which needs further clinical investigation. Clin Cancer Res; 20(15); 4107–14. ©2014 AACR.

Frequency of well-identified oncogenic driver mutations in lung adenocarcinoma of smokers varies with histological subtypes and graduated smoking dose

PURPOSE We performed this analysis to reveal the association between six well-identified oncogenic driver mutations and clinical and pathological features in lung adenocarcinomas from smokers. It may have the potentiality to optimize existing treatment strategies and clinical trial design. METHODS In this series, 230 resected lung adenocarcinomas from smoker (>100 cigarettes in lifetime) at single center (Shanghai Cancer Center, Shanghai, China) were tested for mutation in EGFR, KRAS, BRAF, HER2, EML4-ALK and PIK3CA. Further we compared the mutation frequency with sex, age at diagnosis, stage, differentiation, smoking dose, and histological subtype. RESULTS Among 230 smokers, we detected 100 (43.5%) EGFR mutations, 38 (16.5%) KRAS mutations, 8 (3.5%) PIK3CA mutations, 7 (3.0%) BRAF mutations and 7 (3.0%) EML4-ALK fusions. No HER2 mutation was found. EGFR mutations occurred at a significantly higher frequency in patients with smoking dose ≤20 pack-years (p < 0.001) or age ≥60 years old at diagnosis (p = 0.018). Smoking dose >20 pack-years and age <60 years old at diagnosis were associated with the presence of KRAS mutation. With regard to association between histological subtypes and driver mutation frequency, EGFR mutation had positive correlation with histological subtype micropapillary (p = 0.003), lepidic (p = 0.011), as well as papillary (p = 0.05) predominant adenocarcinoma. Negative correlation was found between EGFR mutation and solid predominant (p < 0.001), as well as invasive mucinous adenocarcinoma (IMA) (p = 0.006). Besides, KRAS mutation had positive correlation with IMA (p = 0.043). The frequency of EGFR mutation decreased with increasing tobacco dose. In contrast, higher frequency of KRAS mutations was observed with increasing tobacco dose. Generally, the frequency of these driver mutations tested in our study decreased with increasing smoking dose. CONCLUSIONS This study represents the first comprehensive and concurrent analysis of these six well-identified driver mutations in a large cohort of lung adenocarcinoma from East-Asian smokers. Our molecular data in conjunction with the clinical and pathological features indicated that prospective genotyping of lung adenocarcinomas from smokers for these genetic alterations could lead to rationally chosen targeted therapy in the overwhelming majority of cases.

The Use of Quantitative Real-Time Reverse Transcriptase PCR for 5′ and 3′ Portions of ALK Transcripts to Detect ALK Rearrangements in Lung Cancers

Purpose: Approximately 3% to 7% of non–small cell lung cancers (NSCLC) harbor an ALK fusion gene, thus defining a tumor group that may be responsive to targeted therapy. The breakpoint in ALK consistently occurs at exon 20 and EML4 or other fusion partners, thus driving a strong expression of ALK kinase domain and resulting in an unbalanced expression in 5′ and 3′ portions of ALK transcripts. We have developed a rapid and accurate method by simultaneously detecting the expression in 5′ and 3′ portions of ALK mRNA. Experimental Design: Quantitative real-time reverse transcriptase PCR (qRT-PCR) was used to examine expression levels of the 5′ and 3′ portions of ALK transcripts in177 NSCLCs, in which EGFR, KRAS, HER2, and BRAF mutations were absent. If unbalanced ALK mRNA expression was seen, ALK rearrangement was assumed to exist. ALK FISH was used to confirm the accuracy of qRT-PCR. RT-PCR and 5′ RACE coupling sequencing identified the fusion variants. Results: Real-time RT-PCR showed excellent sensitivity and specificity (100% and 100%, respectively) for detection of ALK rearrangements in resected specimens. In addition, six novel ALK fusion variants were identified, including one KIF5B-ALK (E17;A20) and five EML4-ALK variants (E6a;A19, E6a/b ins 18;A20, E17b ins 39;A20, E10a/b, E13;A20, and E17 ins 65;A20). Conclusions: Real-time RT-PCR is a rapid and accurate method for diagnosing ALK-rearranged lung cancers. Coupling of 5′ RACE to this method should further facilitate rapid identification of novel ALK fusion genes. Clin Cancer Res; 18(17); 4725–32. ©2012 AACR.