Lung cancer with concurrent EGFR mutation and ROS1 rearrangement: a case report and review of the literature.

ROS1 rearrangement has recently emerged as a new molecular subtype in non-small cell lung cancer, and is predominantly found in lung adenocarcinomas compared with other oncogenes such as EGFR, KRAS, or ALK. Patients who have both mutations are extremely rare. Here we report a 50-year-old female diagnosed with adenocarcinoma with sarcomatoid differentiation, who was shown to have EGFR and ROS1 mutations. The patient was treated surgically and received three cycles of adjuvant postoperative chemotherapy. In addition, we reviewed the previously reported cases and related literature. This presentation will provide further understanding of the underlying molecular biology and optimal treatment for non-small cell lung cancer patients with more than one driver mutation.

Introduction

Non-small cell lung cancer (NSCLC) is still the leading cause of cancer-related deaths worldwide. The prognosis is poor for most patients with NSCLC, even with the most current treatment regimens, which include surgery, chemotherapy, and radiation. Targeted molecular therapy is effective for advanced NSCLC patients with associated gene mutations. Although driver genes, including epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene (KRAS), are common molecules in lung adenocarcinomas, the c-ros oncogene 1 receptor tyrosine kinase (ROS1) rearrangement has been identified in only 1%–2% of NSCLC cases.1,2 Previous studies have suggested that ROS1 fusion is exclusive to EGFR, KRAS, or ALK mutations and presents in a greater percentage of tumors that lack other genetic changes associated with lung cancer.3–5 Nevertheless, at least four patients with an EGFR mutation and ROS1 fusion have been reported thus far in the world literature.6 The patient reported herein is the fifth case, and also the first case with an EGFR exon 21 L858R point mutation and CD74-ROS1 fusion gene. Little is known about the prognostic value, clinical presentation, predictive value for different therapy regimens, and the genetic heterogeneity for two gene-positive NSCLC patients. All protocols in the present study were approved by the Human Clinical and Research Ethics Committees of the Zhejiang Corps Hospital (Jiaxing, People’s Republic of China). The patient provided written informed consent.

Case report

A 50-year-old female who had never smoked was evaluated for persistent cough and shown by computed tomography (CT) scanning to have a 32 mm tumor in the right lower lobe of the lung in November 2015 (Figure 1). No significant medical history was reported and no abnormalities were found on physical examination. Imaging examinations, including abdominal CT, brain magnetic resonance imaging, and bone emission computed tomography, were normal and blood laboratory testing was within normal limits, including a biochemistry and coagulation profile, and routine hematologic parameters.

Figure 1

Treatment of lung adenocarcinoma with sarcomatoid differentiation using different chemotherapy regimens and results of monitoring the CEA levels.

Notes: (A–D) Lung CT scans from (A) November 2015, (B) December 2015, (C) January 2016, and (D) February 2016. (E–H) CT scans of the mediastinum from (E) November 2015, (F) December 2015, (G) January 2016, and (H) February 2016.

Abbreviations: CEA, carcinoembryonic antigen; CT, computed tomography.

The patient underwent resection of the right lower lobe and en bloc resection of the associated hilar and mediastinal lymph nodes by video-assisted thoracic surgery. The postoperative course was uneventful and the patient recovered quickly. The postoperative pathology showed that the tumor was an adenocarcinoma with sarcomatoid differentiation (Figure 2). Immunochemistry staining was positive for the following markers: vimentin; thyroid nuclear factor 1; P63; cytokeratin 7; and cytokeratin 5/6 (Table 1 and Figure 2). The tumor was stage Ib (T2aN0M0). Gene detection for mutations was performed on a formalin-fixed, paraffin-embedded tibia tumor specimen by next-generation sequencing and fusion genes, and c-Met 14 skipping mutation by polymerase chain reaction or fluorescence in situ hybridization on portions of the adenocarcinoma and sarcomatoid differentiation, respectively. A variant of the ROS1 translocation (Table 2 and Figure 3) and the EGFR exon 21 L858R point mutation were detected (Table 3 and Figure 3). The patient received three cycles of postoperative adjuvant chemotherapy. No recurrence of the tumor was noted by CT scanning during 3 months of follow-up care (Figure 1). The CEA level ranged from a pretreatment level of 3.41 ng/mL to a postoperative level of 2.29 ng/mL (Figure 1).

Figure 2

The hematoxylin-eosin staining and the immunohistochemistry in the part of adenocarcinoma and sarcomatoid differentiation.

Notes: (A) The hematoxylin–eosin staining revealed that tumor cells were lung adenocarcinoma (×100). (B) The hematoxylin–eosin staining revealed that tumor cells were sarcomatoid differentiation (×100). (C) Immunohistochemical examination revealed that tumor cells were positive for monoclonal anti-CK7 antibody in a portion of the adenocarcinoma (×100). (D) Immunohistochemical examination revealed that tumor cells were positive for monoclonal anti-CK7 antibody in a portion of the sarcomatoid differentiation (×100). (E) Immunohistochemical examination revealed that tumor cells were positive for monoclonal anti-TTF-1 antibody in a portion of the adenocarcinoma (×100). (F) Immunohistochemical examination revealed that tumor cells were positive for monoclonal anti-TTF-1 antibody in a portion of sarcomatoid differentiation (×100). (G) Immunohistochemical examination revealed that tumor cells were positive for monoclonal antivimentin antibody in a portion of adenocarcinoma (×100). (H) Immunohistochemical examination revealed that tumor cells were positive for monoclonal antivimentin antibody in a portion of sarcomatoid differentiation (×100).

Table 1

Primary antibodies used for immunohistochemical staining

Antibody	Clone	Dilution	Purchased from
Vimentin	EP21	1:100	Zymed Laboratories, Inc.
TTF-1	SPT24	1:100	Zymed Laboratories, Inc.
P63	UMAB4	1:100	Zymed Laboratories, Inc.
CK7	EP16	1:100	Zymed Laboratories, Inc.
CK5/6	D5/16B4	1:100	Zymed Laboratories, Inc.

Notes: Zymed Laboratories, Inc. (South San Francisco, CA, USA).

Abbreviations: CK, cytokeratin; TTF-1, thyroid nuclear factor 1.

Table 2

Gene mutation identified by next-generation sequencing of the patient

Gene	Type
EGFR mut	L858R
KRAS mut	Wild type
BRAF mut	Wild type
PIK3CA mut	Wild type
NRAS mut	Wild type
KIT mut	Wild type
PDGFRA mut	Wild type
ERBB2 mut	Wild type
DDR2 mut	Wild type
ALK mut	Wild type
RET mut	Wild type
FLT3 mut	Wild type
DNMT3A mut	Wild type
NPM1 mut	Wild type
ABL1 mut	Wild type
SMO mut	Wild type
TSC1 mut	Wild type

Abbreviation: mut, mutation.

Figure 3

Schema shows tumor with dual drivers (CD74-ROS1 fusion gene by polymerase chain reaction and EGFR exon 21 L858R point mutation by next-generation sequencing) in a portion of the adenocarcinoma (1), and tumor with no driver or unknown driver in a portion of the sarcomatoid differentiation (2).

Table 3

Noteworthy results identified by PCR or FISH of the patient

Gene	Type
ALK fusion	Negative
ROS1 fusion	CD74-ROS1
RET fusion	Negative
NTRK1 fusion	Negative
c-Met amp	Negative
c-Met 14 skipping mut	Negative

Abbreviations: FISH, fluorescence in situ hybridization; PCR, polymerase chain reaction; mut, mutation.

Discussion

The EGFR gene, which is located on the 12–14 region of short arm of chromosome 7, consists of 28 exons, and most mutations are located within exons 19–21 of the tyrosine kinase domain.7–9 Point mutations in exon 21 and overlapping deletions in exon 19 account for ~85% of all mutations.10,11

The ROS1 rearrangement in NSCLC was discovered by Rikova et al.12 The fusion partners include CD74-, SLC34A2-, SDC4-, EZR-, FIG-, TPM3-, LRIG3-, and KDELR2-. CD74- is the most common fusion partner in NSCLC.3 ROS1 (chromosome 6q22) encodes a receptor tyrosine kinase that belongs to the insulin receptor family and stimulates downstream signaling via the mitogen-activated protein kinases pathway, resulting in enhanced cell growth, proliferation, and decreased apoptosis. The frequency of ROS1 rearrangements ranges from 0.9% to 1.7% in an unselected NSCLC population.1,13,14 However, the frequency increases from 3.9% to 7.4% in lung adenocarcinoma patients with wild-type EGFR/KRAS/ALK.4,5

The EGFR tyrosine kinase inhibitors (TKIs), such as erlotinib, gefitinib, and icotinib, have been widely used as first-line treatment and have higher sensitivity compared to platinum-based chemotherapy in advanced NSCLC patients with EGFR mutations.15–17 Deletions in exon 19 and L858R point mutations in exon 21 are the most sensitive mutations with a clear benefit from EGFR TKI treatment.

ROS1-positive patients do not benefit from treatment with EGFR TKIs.4,5 In contrast, patients appear to benefit from treatment with crizotinib, an orally bioavailable anaplastic lymphoma kinase (ALK) inhibitor.18,19 Crizotinib is currently undergoing Phase III clinical trials globally. It is anticipated that ROS1-positive NSCLC behaves in an analogous manner to EGFR mutant NSCLC, and crizotinib could represent an advance in NSCLC treatment.

Patients who have a ROS1 gene fusion and EGFR mutation are extremely rare. Previous studies have suggested that an EGFR mutation and ROS1 gene fusion are mutually exclusive molecular events. We reviewed the literature for both EGFR and ROS1 mutations in NSCLC and found only five cases, including the present case,6 as shown in Table 4. Indeed, this is the first case in the Han Chinese population identified with a concurrent EGFR exon 21 L858R point mutation and a ROS1 fusion gene with a fusion partner (CD74-). Table 4 shows the clinical features of patients with the concomitant genes presented in our study include never-smokers (5/5), adenocarcinoma (4/5), and adenocarcinoma with sarcomatoid differentiation (1/5), exon 19 (3/5), 20 insertion (1/5), and an exon 21 (1/5) mutation of EGFR. Two patients with advanced NSCLC harboring concomitant ROS1 rearrangements and an EGFR exon 19 deletion achieved a partial response after first-line gefitinib treatment. The patient presented herein underwent surgery and received three cycles of postoperative adjuvant chemotherapy based on pathology stage Ib and uncleared results of postoperative adjuvant TKI therapy, according to the National Comprehensive Cancer Network clinical practice guidelines.

Table 4

Clinical features of five patients with the ROS1 fusion gene and EGFR mutation

Patient no	1	2	3	4	5 (present case)
Ethnicity	Chinese	Chinese	Chinese	Chinese	Chinese
Age (years old)	NA	NA	NA	NA	50
Sex	NA	NA	NA	NA	Female
Smoking history	Never smoker	Never smoker	Never smoker	Never smoker	Never smoker
Histology	Adenocarcinoma	Adenocarcinoma	Adenocarcinoma	Adenocarcinoma	Adenocarcinoma with sarcomatoid differentiation
Primary lesion	NA	NA	NA	NA	The right inferior lung lobe
TNM staging	NA	NA	NA	NA	T2aN0M0 stage Ib
EGFR mutation status	19del	19del	19del	20-ins	L858R
ROS1 fusion partner	NA	NA	NA	NA	CD74
First-line treatment	Gefitinib	Gefitinib	NA	NA	Surgery
First-line treatment assessment	Partial response	Partial response	NA	NA	R0 resectiona

Note:

Complete resection with no microscopic residual tumor.

Abbreviation: NA, not available.

Limitations

Our study had some limitations. First, one case of a primary lung tumor included a dominance of adenocarcinoma cells with sarcomatoid differentiation, so we do not know whether or not both mutations were related to tumor tissue heterogeneity. Second, the response to TKIs in this patient is unknown because TKIs were not used.

Conclusion

We report a rare case of lung cancer in a patient harboring both an EGFR mutation and a ROS1 fusion gene. The surgery and postoperative adjuvant chemotherapy showed a good response. For patients with this subtype, further research and experience are needed to summarize the biologic features and optimal modes of treatment, including targeted therapy in advanced lung cancer patients.