Effectiveness of crizotinib in a patient with mesenchymal-epithelial transition overexpression/fluorescence in situ hybridization-negative/next-generation sequencing-negative advanced lung adenocarcinoma: a case report

Introduction

In recent years, the tyrosine kinase receptor mesenchymal-epithelial transition (MET) has become a target in non-small cell lung cancer (NSCLC). Crizotinib, a potent tyrosine kinase inhibitor (TKI) of anaplastic lymphoma kinase (ALK) and ROS1, has demonstrated its remarkable therapeutic effect in patients with MET amplified or MET exon 14 skipping mutated advanced-stage non-small-cell lung cancer in several previous reports (1-5). Methods to detect MET alteration includes immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), next-generation sequencing (NGS) and reverse transcription polymerase chain reaction (RT-PCR). Few cases reported response to crizotinib in advanced NSCLC patients according to the results of MET IHC staining. In this article, we report a case of crizotinib effectiveness in a pretreated patient with advanced lung adenocarcinoma detected as MET overexpression/FISH-negative/NGS-negative.

Case presentation

A 53-year-old male smoker visited our hospital with the chief complaint of causing cough and fever on March 12, 2018. Physical examination revealed enlarged lymph nodes in the left supraclavicular region. The patient underwent computed tomography (CT) scanning, which showed space-occupying lesions in the right lung and multiple enlarged lymph nodes in the mediastinum that were preliminarily determined to be lung adenocarcinoma by bronchoscopic examination and no distant metastatic lesions was detected (Figure 1A,B). Aspiration biopsy of the left supraclavicular lymph node was performed and histological examination revealed a lymph node invaded by adenocarcinoma cells which originated from primary adenocarcinoma of lung confirmed by IHC (Figure 1C,D). In addition, IHC revealed that the metastatic tumor expressed MET protein which was strong positive (score 3+ with SP44 from Ventana Medical Systems, USA) (Figure 1E). FISH analysis showed neither MET amplification nor ALK or ROS1 rearrangements (MET: Vysis MET SpectrumRed/CEP7 SpectrumGreen, Abbott Molecular, USA; ALK: Vysis ALK Dual Color, Abbott Molecular, USA; ROS1: Vysis ROS1 Dual color, Abbott Molecular, USA) (Figure 1F). We performed targeted NGS using biopsy tissue from left supraclavicular lymph node. Genomic DNA was profiled by using a capture-based targeted sequencing panel (Burning Rock Biotech, Guangzhou, China), including all exons in 56 genes and selected introns in MET, ALK, ROS1, RET, NTRK1, FGFR3 and FGFR1. Detailed procedure was reported in our previous study (6). The results of sequencing showed that no mutation was detected in MET gene (Figure 1G). The patient was treated with pemetrexed-carboplatin doublet chemotherapy initially on March 23, 2018. After two cycles of chemotherapy, the primary lesion maintained as stable disease (Figure 1H), but a metastatic tumor occurred in the right adrenal gland (Figure 1I). Considering strong positive staining of MET, we finally decided to administrate crizotinib 250 mg twice daily after multidisciplinary discussion on May 10, 2018. After one month of crizotinib treatment, the primary lesion and the metastatic tumor in the right adrenal gland both achieved a marked partial response (PR) (Figure 1J,K). The patient continued to receive crizotinib with no significant cancer progression as of December 2018.

Figure 1 Illustration of the computed tomography images, histopathological, immunohistochemical, fluorescence in situ hybridization and next-generation sequencing results. (A) CT scan of thorax and mediastinal lymph nodes at diagnosis. A lung mass localized in the right lower lobe with an enlarged lymph node in the mediastinum (arrows indicate primary tumor and lymph node); (B) abdominal CT scan at diagnosis. No adrenal lesions were observed; (C) hematoxylin-eosin staining of the patient’s aspiration biopsy sample. Picture magnification: 20×; (D) TTF-1 immunohistochemistry using the SP141 monoclonal antibody. Picture magnification: 20×; (E) C-Met immunohistochemistry using the SP44 monoclonal antibody. We observed a diffuse and intense c-Met immunostaining in tumor cells (score 3+). Picture magnification: 20×; (F) MET FISH using Vysis LSI MET SpectrumRed/CEP7 SpectrumGreen probe. We observed a negative result of MET amplification with MET to CEP7 ratio <2. Picture magnification: 60×; (G) next-generation sequencing analysis of MET exon 14 mutation. We observed no mutation in MET exon 14; (H) CT scan of thorax and mediastinal lymph nodes after two cycles of chemotherapy. The dominant mass and the enlarged mediastinal lymph node maintained stable (arrows indicate primary tumor and lymph node); (I) abdominal CT scan after two cycles of chemotherapy. A right adrenal lesion was observed (arrow indicates adrenal gland); (J) CT scan of thorax and mediastinal lymph nodes after one month of crizotinib treatment. A marked response to therapy with significant decrease of the dominant mass and lymph node was observed (arrows indicate primary tumor and lymph node); (K) abdominal CT scan after one month of crizotinib treatment. A significant decrease in the size of right adrenal lesion was observed (arrow indicates adrenal gland). CT, computed tomography; TTF-1, thyroid transcription factor-1; MET, mesenchymal-epithelial transition; FISH, fluorescence in situ hybridization.

Discussion

While crizotinib is recommended in advanced-stage NSCLC patients with MET amplification or MET exon 14 skipping mutation by NCCN guidelines, we report its effectiveness in an advanced lung adenocarcinoma considered MET IHC-positive/FISH-negative/NGS-negative.

As for detection of MET alteration, no gold standard method is widely accepted to determine appropriate patients with NSCLC who can benefit from crizotinib. The need for accurate detection of MET alteration has become much more important. Previous studies have described the correlation between MET amplification and MET protein expression, and revealed that almost all patients who displayed amplification of the MET gene also were positive for MET protein expression, while only half of the IHC positive patients had amplification (7,8). Therefore, for detection of MET alteration, many centers routinely applied IHC as initially screening tool due to its rapid and inexpensive advantage, and those with moderate or intense staining indicative of MET gene expression are then tested by FISH for confirmation of MET amplification.

Few studies reported the treatment efficacy of crizotinib in NSCLC patients with MET overexpression/FISH-negative. Li et al. demonstrated that 11 advanced NSCLC patients with de-novo overexpression of MET achieved PR to crizotinib, of which 3 patients showed MET IHC strong positive without MET amplification and ALK or ROS1 rearrangements (9). Our case also achieved PR to crizotinib based on MET IHC staining. However, the 3 patients in Li et al.’s study did not undergo gene sequencing to determine the MET exon 14 mutational status, and hence the effective treatment of crizotinib in these 3 patients may be attributed to the presence of MET exon 14 mutation. In view of the above-mentioned uncertainty, NGS was applied into our case and no MET exon 14 mutation was found, in addition to negative finding for MET amplification and ALK or ROS1 rearrangements.

We herein infer from this case that MET overexpression could be a biomarker for predicting efficacy of crizotinib. Further studies awaiting to be done for collecting more patients with MET overexpression for evaluating efficacy of crizotinib.

Acknowledgments

The authors thank Jiali Mu and Ruomei Dong for their technical assistance.

Funding: This work was supported by Beijing Municipal Science & Technology CommissionNo. LC2015A13 and National Key R&D Program of China (2017YFC1308700).

Footnote

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/tcr.2019.03.14). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this manuscript and any accompanying images.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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