Clinical application of amplicon-based next-generation sequencing to therapeutic decision making in lung cancer

Clinical sequencing using a next-generation sequencing-based multiplex gene assay in patients with advanced solid tumors

Advances in next‐generation sequencing (NGS) technologies have enabled physicians to test for genomic alterations in multiple cancer‐related genes at once in daily clinical practice. In April 2015, we introduced clinical sequencing using an NGS‐based multiplex gene assay (OncoPrime) certified by the Clinical Laboratory Improvement Amendment. This assay covers the entire coding regions of 215 genes and the rearrangement of 17 frequently rearranged genes with clinical relevance in human cancers. The principal indications for the assay were cancers of unknown primary site, rare tumors, and any solid tumors that were refractory to standard chemotherapy. A total of 85 patients underwent testing with multiplex gene assay between April 2015 and July 2016. The most common solid tumor types tested were pancreatic (n = 19; 22.4%), followed by biliary tract (n = 14; 16.5%), and tumors of unknown primary site (n = 13; 15.3%). Samples from 80 patients (94.1%) were successfully sequenced. The median turnaround time was 40 days (range, 18–70 days). Potentially actionable mutations were identified in 69 of 80 patients (86.3%) and were most commonly found in TP53 (46.3%), KRAS (23.8%), APC (18.8%), STK11 (7.5%), and ATR (7.5%). Nine patients (13.0%) received a subsequent therapy based on the NGS assay results. Implementation of clinical sequencing using an NGS‐based multiplex gene assay was feasible in the clinical setting and identified potentially actionable mutations in more than 80% of patients. Current challenges are to incorporate this genomic information into better therapeutic decision making.

Changing the Therapeutic Landscape in Non-small Cell Lung Cancers: the Evolution of Comprehensive Molecular Profiling Improves Access to Therapy

Targeting genomic alterations has led to a paradigm shift in the treatment of patients with lung cancer. In an effort to better identify potentially actionable alterations that may predict response to FDA-approved and or investigational therapies, many centers have migrated towards performing targeted exome sequencing in patients with stage IV disease. The implementation of next-generation sequencing (NGS) in the evaluation of tumor tissue from patients with NSCLC has led to the discovery of targetable alterations in tumors that previously had no known actionable targets by less comprehensive profiling. An improved understanding of the molecular pathways that drive oncogenesis in NSCLC and a revolution in the technological advances in NGS have led to the development of new therapies through biomarker-driven clinical trials. This review will focus on the advances in molecular profiling that continue to fuel the revolution of precision medicine, identifying targets such as MET exon 14 skipping alterations and select recurrent gene alterations with increasing frequency.

Routine genetic testing of lung cancer specimens derived from surgery, bronchoscopy and fluid aspiration by next generation sequencing

After the development of EGFR tyrosine kinase inhibitors (TKIs), genetic testing of EGFR became required for effective treatment of lung cancer. Initially, the testing was conducted separately for each mutated region. However, many EGFR mutations have since been identified that determine the efficacy of EGFR-TKIs. Therefore, genetic testing of EGFR by next generation sequencing (NGS) may be a suitable strategy for lung cancer. Here we examined the applicability of the NGS method in regard to sensitivity, time and cost. A total of 939 specimens were obtained from 686 lung cancer patients at our hospital. DNA and RNA were simultaneously extracted from specimens derived from surgery, bronchoscopy, and fluid aspiration. Specimens included cerebrospinal fluid, pleural effusion, abdominal fluid, and pericardial effusion. From RNA, target regions (EGFR, KRAS, ALK fusion and RET fusion) were enriched by RT-PCR and sequenced with MiSeq. From DNA, PCR or PCR-RFLP conventional methods were performed. NGS and conventional methods were carried out routinely per week. Among the total 939 specimens, 38 specimens could not be examined with NGS. Among these, 34 specimens were analyzed by conventional testing with simultaneously extracted DNA. The remaining four specimens could not be tested with either method. Compared with the conventional method, the concordance rate of mutations was 99% (892/901), excluding specimens with NGS failure. The time period required from processing of specimens to results was 4 days, and the cost per sample was sufficiently low. In conclusion, the genetic testing with NGS method was useful for lung cancer treatment. The cost, sensitivity and time were able to tolerate routine examinations.

Tumor volume determines the feasibility of cell-free DNA sequencing for mutation detection in non-small cell lung cancer

Next‐generation sequencing (NGS) and digital PCR technologies allow analysis of the mutational profile of circulating cell‐free DNA (cfDNA) in individuals with advanced lung cancer. We have now evaluated the feasibility of cfDNA sequencing for mutation detection in patients with non‐small cell lung cancer at earlier stages. A total of 150 matched tumor and serum samples were collected from non‐small cell lung cancer patients at stages IA–IIIA. Amplicon sequencing with DNA extracted from tumor tissue detected frequent mutations in EGFR (37% of patients), TP53 (39%), and KRAS (10%), consistent with previous findings. In contrast, NGS of cfDNA identified only EGFR,TP53, and PIK3CA mutations in three, five, and one patient, respectively, even though adequate amounts of cfDNA were extracted (median of 4936 copies/mL serum). Next‐generation sequencing showed a high accuracy (98.8%) compared with droplet digital PCR for cfDNA mutation detection, suggesting that the low frequency of mutations in cfDNA was not due to a low assay sensitivity. Whereas the yield of cfDNA did not differ among tumor stages, the cfDNA mutations were detected in seven patients at stages IIA–IIIA and at T2b or T3. Tumor volume was significantly higher in the cfDNA mutation‐positive patients than in the negative patients at stages T2b–T4 (159.1 ± 58.0 vs. 52.5 ± 9.9 cm³, P = 0.014). Our results thus suggest that tumor volume is a determinant of the feasibility of mutation detection with cfDNA as the analyte.

Clinical Impact of Hybrid Capture-Based Next-Generation Sequencing on Changes in Treatment Decisions in Lung Cancer

INTRODUCTION

Targeted therapy significantly prolongs survival in lung adenocarcinoma. Current diagnostic guidelines include only EGFR and anaplastic lymphoma receptor tyrosine kinase gene (ALK) testing. Next-generation sequencing (NGS) reveals more actionable genomic alterations than do standard diagnostic methods. Data on the influence of hybrid capture (HC)-based NGS on treatment are limited, and we investigated its impact on treatment decisions and clinical outcomes.

METHODS

This retrospective study included patients with advanced lung cancer on whom HC-based NGS was performed between November 2011 and October 2015. Demographic and clinicopathologic characteristics, treatments, and outcome data were collected.

RESULTS

A total of 101 patients were included (median age 63 years [53% females, 45% never-smokers, and 85% with adenocarcinoma]). HC-based NGS was performed upfront and after EGFR/ALK testing yielded negative or inconclusive results in 15% and 85% of patients, respectively. In 51.5% of patients, HC-based NGS was performed before first-line therapy, and in 48.5%, it was performed after treatment failure. HC-based NGS identified clinically actionable genomic alterations in 50% of patients, most frequently in EGFR (18%), Ret proto-oncogene (RET) (9%), ALK (8%), Mesenchymal-epithelial transition factor (MET) receptor tyrosine kinase gene (6%), and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) (5%). In 15 patients, it identified EGFR/ALK aberrations after negative results of prior standard testing. Treatment strategy was changed for 43 patients (42.6%). The overall response rate in these patients was 65% (complete response 14.7%, partial response 50%). Median survival was not reached. Immunotherapy was administered in 33 patients, mostly without an actionable driver, with a presenting disease control rate of 32%, and with an association with tumor mutation burden.

CONCLUSIONS

HC-based NGS influenced treatment decisions in close to half of the patients with lung adenocarcinoma and was associated with an overall response rate of 65%, which may translate into a survival benefit.

A retrospective analysis of the clinicopathological and molecular characteristics of pulmonary blastoma

Purpose

The aim of this study was to analyze and summarize the clinicopathological and molecular characteristics of classic biphasic pulmonary blastoma (PB) to improve its diagnosis and treatment.

Patients and methods

A retrospective analysis was performed in patients who were diagnosed with PB at Sun Yat-Sen University Cancer Center from March 1995 to March 2015. Genomic DNA was profiled using a capture-based targeted sequencing panel.

Results

Sixteen patients with an average age of 40 years were included in this study. Accurate preoperative diagnosis was very challenging as surgically resected tissues with immunohistochemical staining were required for the diagnosis. Surgery was the optimal treatment for localized disease and there was no standard management for metastatic disease. Mutations were detected among 9 out of the 56 genes profiled, including BRCA2, ERBB4, ALK, MET, BRAF, RAF1, PTEN, EGFR, and PIK3CA.

Conclusion

Due to the low incidence rate and the reclassification of PB, no standard treatment is available. Although the numbers of cases are few with varying individual experiences, it is important to improve our understanding regarding this rare lung cancer. Targeted DNA sequencing may be of clinical use for molecular testing and the effects of targeted therapy need to be confirmed.

Case report: Durable response to afatinib in a patient with lung cancer harboring two uncommon mutations of EGFR and a KRAS mutation

Comprehensive genomic profiling for non-small cell lung cancer (NSCLC) is likely to identify more patients with rare genetic alterations including uncommon epidermal growth factor receptor gene (EGFR) mutations. It remains unclear how such patients should be treated, however. We here report a case of NSCLC positive for two uncommon mutations of EGFR and a KRAS mutation, including its treatment with the second-generation EGFR tyrosine kinase inhibitor (TKI) afatinib. Tumor specimen obtained by a NSCLC patient with no smoking history was analyzed by next-generation sequencing. Comprehensive genomic profiling revealed that the patient harbored the EGFR mutations G719C and S768I as well as the E49K mutation of KRAS. Treatment with afatinib was clinically effective as confirmed by PET-CT scans of bone metastases and by a marked decrease in the serum concentration of carcinoembryonic antigen. Afatinib was the most effective among seven EGFR-TKIs tested in inhibiting the growth of Ba/F3 cells expressing EGFR(S768I), showing an efficacy similar to that apparent with cells expressing the common EGFR mutant L858R, whereas first- and third-generation EGFR-TKIs were markedly less effective against EGFR(S768I) than against EGFR(L858R). These data suggest that EGFR-TKIs differ in their activity toward cells expressing EGFR(S768I) in vitro. Consistently, afatinib was clinically effective for the treatment of NSCLC harboring G719C and S768I mutations of EGFR. Further studies are warranted to determine the most appropriate EGFR-TKI for treatment of NSCLC harboring uncommon EGFR mutations.

Detection of lung adenocarcinoma with ROS1 rearrangement by IHC, FISH, and RT-PCR and analysis of its clinicopathologic features

Objective

To detect ROS1 rearrangement using three different assays, including immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and reverse transcription polymerase chain reaction (RT-PCR), and to analyze the clinicopathologic features of ROS1 rearrangement in patients with lung adenocarcinoma.

Methods

One hundred eighty-three consecutive patients with lung adenocarcinoma with operation and follow-up data were analyzed for ROS1 rearrangement by IHC, FISH, and RT-PCR. PCR products of the RT-PCR-positive samples were sequenced for confirmation of the specific fusion partners.

Results

Three of the 183 (1.64%) cases were identified to be positive for ROS1 rearrangement through all three methods. The fusion patterns were CD74 e6-ROS1 e32, CD74 e6-ROS1 e34, and TPM3 e8-ROS1 e35, respectively. FISH-positive cases showed two types of signals, single 3′ signals (green) and split red and green signals. Using FISH as a standard method, the sensitivity and specificity of ROS1 IHC with 1+ staining or more were 100% and 96.67%, respectively. The sensitivity and specificity of RT-PCR were both 100%. Univariate analysis identified female sex (P=0.044), Stage I disease (P<0.001), and ROS1-negative status (P=0.022) to be significantly associated with longer overall survival.

Conclusion

IHC, FISH, and RT-PCR are all effective methods for the detection of ROS1 rearrangement. IHC would be a useful screening method in routine pathologic laboratories. RT-PCR can detect exact fusion patterns. ROS1 rearrangement may be a worse prognostic factor. The exact correlation of ROS1 rearrangement with prognosis and whether different fusion types are correlated with different responses to targeted therapy need to be further investigated.