Simultaneous VENTANA IHC and RT-PCR testing of ALK status in Chinese non-small cell lung cancer patients and response to crizotinib

Concordance Analysis of ALK Gene Fusion Detection Methods in Patients with Non-Small-Cell Lung Cancer from Chile, Brazil, and Peru

About 4% to 7% of the non-small-cell lung cancer patients have anaplastic lymphoma kinase (ALK) rearrangements, and specific targeted therapies improve patients' outcomes significantly. ALK gene fusions are detected by immunohistochemistry or fluorescent in situ hybridization as gold standards in South America. Next-generation sequencing-based assays are a reliable alternative, able to perform simultaneous detection of multiple events from a single sample. We analyzed 4240 non-small-cell lung cancer samples collected in 37 hospitals from Chile, Brazil, and Peru, where ALK rearrangements were determined as part of their standard of care (SofC) using either immunohistochemistry or fluorescent in situ hybridization. A subset of 1450 samples was sequenced with the Oncomine Focus Assay (OFA), and the concordance with the SofC tests was measured. An orthogonal analysis was performed using a real-time quantitative PCR echinoderm microtubule-associated protein-like 4-ALK fusion detection kit. ALK fusion prevalence is similar for Chile (3.67%; N = 2142), Brazil (4.05%; N = 1013), and Peru (4.59%; N = 675). Although a comparison between OFA and SofC assays showed similar sensitivity, OFA had significantly higher specificity and higher positive predictive value, which opens new opportunities for a more specific determination of ALK gene rearrangements.

IHC versus FISH versus NGS to detect ALK gene rearrangement in NSCLC: all questions answered?

AIMS

Anaplastic lymphoma kinase (ALK) rearranged non-small cell lung carcinoma (NSCLC) is a distinct molecular subtype and rapid approval of ALK tyrosine kinase inhibitors (TKIs) has necessitated rapid and sensitive diagnostic modalities for the detection of this alteration. Gene rearrangements can be identified using many techniques including fluorescence in situ hybridisation (FISH), reverse transcriptase-PCR, next-generation sequencing (NGS) and immunohistochemistry (IHC) for fusion oncoprotein expression. We aimed to determine the concordance between IHC, FISH and NGS for ALK biomarker detection, and determine differences in sensitivity, and survival outcomes.

METHODS

We analysed the concordance between IHC using D5F3 monoclonal antibody, FISH (break-apart) and NGS using a custom panel containing 71 different ALK variants.

RESULTS

Among 71 cases included in this study, FISH was evaluable in 58 cases. The concordance of ALK IHC with FISH was 75.9% and that with NGS was 84.5%. The sensitivities of FISH and NGS were 75.6% and 87.5%, respectively. The median progression-free survival of ALK IHC-positive and FISH-negative group was 5.5 months and that of both positive was 9.97 months.

CONCLUSION

Although NGS offers a better throughput and visualisation, IHC still remains the quintessential screening tool in upfront diagnosis of ALK rearranged NSCLC.

Comparison of Next-Generation Sequencing and Ventana Immunohistochemistry in Detecting ALK Rearrangements and Predicting the Efficacy of First-Line Crizotinib in Patients with Advanced Non-Small Cell Lung Cancer

Introduction

Reliable diagnostic approaches to detect ALK rearrangement are critical for selecting patients eligible for crizotinib therapy. This study aimed to compare next-generation sequencing (NGS) and Ventana immunohistochemistry (IHC) in evaluating ALK rearrangements and evaluate their impact on first-line crizotinib efficacy.

Patients and Methods

A total of 472 NSCLC patients were identified as ALK-positive by NGS and/or IHC between March 2014 and February 2020. The concordance of ALK detection, overall response rate (ORR), and progression-free survival (PFS) were analyzed for 319 patients who received front-line crizotinib.

Results

First-line crizotinib (n=319) significantly prolonged PFS in comparison with chemotherapy (n=46; 12.0 vs 6.8 months; p<0.0001). Of the 76 crizotinib-treated patients whose ALK status was assessed by both NGS and IHC, 78.9% of the patients had concordant ALK status (NGS-positive/IHC-positive), 18.4% patients were NGS-positive but IHC-negative, and 2 patients were IHC-positive but NGS-negative. Different detection assays confer no statistical difference in ORR and PFS with first-line crizotinib. The ORR in NGS only, IHC only, and both NGS and IHC was 84.3%, 90.1%, and 88.1%, respectively, while PFS was 11.4, 13.0, and 11.0 months, respectively. The ORR in NGS-positive/IHC-positive and NGS-positive/IHC-negative patients was 85.4% and 92.8%, respectively. Compared to NGS-positive/IHC-positive patients, those with NGS-positive/IHC-negative results had a trend of shorter PFS but statistical significance was not reached (mPFS, 5.9 months vs 11.5 months, p=0.43).

Conclusion

Our results demonstrate that ALK status detected by NGS and/or IHC is reliable in identifying patients with ALK-positive NSCLC who will benefit from ALK inhibitor therapy.

Clinical Significance of Trk Receptor Expression as a New Therapeutic Target in Hepatocellular Carcinoma

Oncogenic fusion of the tropomyosin receptor kinase (Trk) receptor family encoded by the NTRK gene has been found in several carcinomas. About ten targeted therapies have been developed and clinical trials are in progress. However, the results of studies on expression of the Trk receptor in HCC have not yet been published. Immunohistochemical staining was performed using anti-TrkA+B+C antibody (ab181560, Abcam) in 288 curatively resected primary HCC samples, and the correlation between Trk expression and NTRK copy number was assessed. Targeted next generation sequencing was performed in cases with Trk overexpression to detect NTRK fusion genes. Overexpression of Trk protein was observed in 21 (7.3%) of 288 cases. The Trk overexpression group showed a trend toward shorter recurrence-free survival (RFS) (p = 0.092) and overall survival (OS) (p = 0.079) than the low expression group, with frequent multicentric occurrence. Differences in RFS and OS were statistically significant in specific sub-populations including AJCC T1 stage HCCs, tumors less than 5 cm, patients without cirrhosis, tumors without vascular invasion, or Edmondson grades I and II. Trk expression was also an independent prognostic factor in both RFS and OS. Trk expression was not associated with copy number of each NTRK gene, and NTRK fusion was not detected in HCCs with Trk overexpression. Trk expression might play an important role in the development and progression of HCC, and emerging target therapy against the Trk protein could be applicable in patients with Trk-overexpressing HCC.

Clinical evaluation of the effectiveness of fusion-induced asymmetric transcription assay-based reverse transcription droplet digital PCR for ALK detection in formalin-fixed paraffin-embedded samples from lung cancer

BACKGROUND

Accurate detection of anaplastic lymphoma kinase (ALK) rearrangement is the prerequisite for anti-ALK therapy for the patient with non-small cell lung cancer (NSCLC). Fusion-induced asymmetric transcription assay (FIATA)-based reverse transcription droplet digital PCR (RT-ddPCR) was developed and performed for ALK status survey in NSCLC samples.

METHODS

A total of 269 cases of formalin-fixed paraffin-embedded (FFPE) specimens from NSCLC, in which ALK status was confirmed by both fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), were analyzed by FIATA-based RT-ddPCR.

RESULTS

In the ALK-positive group, the 3' ALK transcript copies range was 336.6-107 955.4, and the R3 [(the ratio of the 3' ALK transcript copy numbers to the internal reference gene transcript copy numbers) × 100] was 17.23-672.77. In the ALK-negative group, the 3' ALK transcript copies range was 3.7-1370.6, and the R3 range was 0.10-15.57. The lowest R3 level in the ALK-positive group was significantly higher than the highest R3 level in the ALK-negative group. A positive correlation between the proportion of cancer cells in the tissue section and ALK RNA expression level (R3) was found (P < 0.05). There was no relationship between the percentage of FISH positive cells or FISH positive signal patterns and R3 level of the ALK gene. Compared with FISH and IHC, the clinical sensitivity and specificity of FIATA-based RT-ddPCR for ALK detection were 100%, respectively.

CONCLUSIONS

An absolute quantitative FIATA-based RT-ddPCR was developed and validated for ALK fusion detection in NSCLC. This method can rapidly, accurately, and objectively classify ALK types and help with individual therapy.

Catalog of 5' Fusion Partners in ALK-positive NSCLC Circa 2020

Since the discovery of anaplastic lymphoma kinase fusion-positive (ALK+) NSCLC in 2007, the methods to detect ALK+ NSCLC have evolved and expanded from fluorescence in situ hybridization and immunohistochemistry to next-generation DNA sequencing, targeted RNA sequencing, and whole transcriptome sequencing. As such, the deep sequencing methods have resulted in the expansion of distinct fusion partners identified in ALK+ NSCLC to 90 (one variant PLEKHM2-ALK is found in small cell lung cancer but included in this catalog) by the end of January 2020; about 65 of them (since 2018) and most of the recent novel fusion partners were reported from China. Thirty-four of the distinct fusion partners are located on the short arm of chromosome 2; 28 of these 34 fusion partners are located on 2p21-25, in which ALK is located on 2p23.2-p23.1. Many of these new ALK+ NSCLC fusion variants have responded to ALK tyrosine kinase inhibitors (TKIs). Several of these novel ALK fusion variants were identified as being resistant to EGFR TKIs or as dual 3'ALK fusions. In addition, at least 28 intergenic ALK rearrangements have also been reported, with three of them reported as responding to crizotinib. This review aims to serve as a central source of reference of fusion partners in ALK+ NSCLC for clinicians and scientists. We aim to update and improve the list going forward.

A novel SOS1-ALK fusion variant in a patient with metastatic lung adenocarcinoma and a remarkable response to crizotinib

OBJECTIVES

Transforming anaplastic lymphoma kinase (ALK) gene rearrangements are well known as a unique subset of non-small cell lung cancer (NSCLC) with mutations other than EGFR. Currently, crizotinib is the standard first-line treatment for ALK-positive NSCLC.

MATERIALS AND METHODS

With advances in detection methods, more and more uncommon ALK fusion partners have been identified. Herein we present a novel SOS1-ALK fusion and the efficacy of crizotinib in an advanced NSCLC patient harboring this type of fusion.

RESULTS

A 52-year-old Chinese man had left upper lobe primary NSCLC and synchronous multiple lung metastases (cT2N3M1, stage IV). The ultrasound-guided fine-needle aspiration cytology of palpable left supraclavicular lymph nodes and the results of immunohistochemistry staining supported the diagnosis of metastatic lung adenocarcinoma. Using a next-generation sequencing assay (NGS), we showed that the tumor had a SOS1-ALK fusion which the breakpoints was (S2, A20) rather than other actionable mutations. Therefore, the patient received first-line crizotinib and experienced a remarkable tumor response and has tolerated crizotinib well until this writing.

CONCLUSION

Considering this rare SOS1-ALK fusion and remarkable response to an ALK-inhibitor, it is important to be aware of the presence of SOS1-ALK fusions in patients with advanced NSCLC to better guide targeted therapy. Precision methods, such as NGS for oncogenic alteration detection, should also be encouraged in clinical practice.

Molecular and clinical analysis of Chinese patients with anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer

Anaplastic lymphoma kinase (ALK) fusions have been recognized as a therapeutic target in non‐small cell lung cancer (NSCLC). However, molecular signatures and clinical characteristics of the Chinese population with ALK‐rearranged NSCLC are not well elucidated. In the present study, we carried out targeted next‐generation sequencing on tissue and plasma ctDNA samples in 1688 patients with NSCLC. Overall, ALK fusions were detected in 70 patients (4.1%), and the frequencies of ALK fusions detected in tissue and plasma samples were 5.1% and 3.3%, respectively. Additionally, the prevalence of breakpoint locations for EML4‐ALK fusions in ctDNA was significantly correlated with that in tumor tissues (R² = .91, P = .045). According to age, the incidence rates of ALK fusions among young (age <45 years), middle‐aged (between 45 and 70 years) and elderly (>70 years) patients were significantly different (P < .001). In 70 ALK‐rearranged cases, coexistence of epidermal growth factor receptor (EGFR) alterations and ALK fusions was detected in 12 cases (17.1%) and EGFR mutations tended to coexist with non‐EML4‐ALK rearrangements. Notably, novel ALK fusion partners, including TRIM66,SWAP70,WNK3,ERC1,TCF12 and FBN1 were identified in the present study. Among EML4‐ALK fusion variants, patients with variant V1 were younger than patients with variant V3 (P = .023), and TP53 mutations were more frequently concurrent with variant V3 compared with variant V1 (P = .009). In conclusion, these findings provide new insights into the molecular‐clinical profiles of patients with ALK‐rearranged NSCLC that may improve the treatment strategy of this population.

Chinese perspectives on clinical efficacy and safety of alectinib in patients with ALK-positive advanced non-small cell lung cancer

The incidence of lung cancer is increasing in China, in contrast to trends in Western countries, due to the increasing numbers of smokers and high levels of air pollution. Non-small-cell lung cancer (NSCLC) is the most common form of lung cancer, accounting for approximately 85% of lung cancers. Better understanding of the pathogenesis of NSCLC has led to the identification of multiple genetic mutations and chromosomal translocations such as those in the anaplastic lymphoma kinase (ALK) gene. To facilitate the identification of treatment targets, multiple guidelines (European Society for Medical Oncology, National Comprehensive Cancer Network, and American Society of Clinical Oncology) now recommend screening for genetic factors to help guide treatment decisions. In recent years, multiple ALK inhibitors have been developed to treat NSCLC, including the first-generation tyrosine kinase inhibitor (TKI) crizotinib; second-generation TKIs such as ceritinib, ensartinib, brigatinib, and alectinib; the third-generation TKI lorlatinib; and the fourth-generation TKI repotrectinib. These agents differ in structure, potency, and activity, both systemically and their effects on central nervous system (CNS) metastases. Recently, alectinib was approved in China to treat patients with locally advanced or metastatic NSCLC that were ALK+. Alectinib has demonstrated activity against NSCLC, including metastases within the CNS, with better tolerability than crizotinib. These ALK inhibitors represent significant advances in the treatment of NSCLC and yet patients will likely still exhibit disease progression. Alectinib offers greater potency with greater specificity as well as a better toxicity profile than many other TKIs that are currently available. Here, we review the role of ALK as a therapeutic target in NSCLC, the testing methods for identifying ALK-rearranged NSCLC, and the various TKIs currently being used or explored for treatment in this setting, with a focus on alectinib from a Chinese perspective.