Complete remission through icotinib treatment in Non-small cell lung cancer epidermal growth factor receptor mutation patient with brain metastasis: A case report.

Brain metastasis (BM) has been universally recognized as a poor prognostic factor in non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have shown efficacy in treating BM with an EGFR mutation. This paper reports a case of BM patient with EGFR-mutated NSCLC. According to the findings, a complete remission (CR) of the BM was achieved by icotinib treatment without conducting a radiotherapy, which was followed by a resection of the primary lung cancer lesion and lymph nodes. After one-year follow-up, the disease progressed to liver metastasis and liver lesion biopsy showed a T790M mutation. The patient responded well to the combination treatment of AZD9291 and icotinib after the failure of transcatheter arterial chemoembolization (TACE). This case report suggests that icotinib has a sustainable anticancer response to BM and the combination with icotinib and AZD9291 is effective for liver metastasis with T790M.

Introduction

The incidence of brain metastases (BM) is approximately 20%–40% in patients with non-small cell lung cancer (NSCLC) [1]. A number of clinical trials and retrospective analyses were conducted in order to compare the efficacy and safety among different treatment approaches used to control BM status [2-7]. Medical management, including surgical treatments, radiation therapy (whole brain radiation, focal beam and stereotactic radiation therapy, radiosurgery), chemotherapy, and combined therapies, remained as the major treatment options. In selected cases, complete remission of a single BM provides a surgical opportunity to remove primary lung cancer lesions, which consequently prolongs survival times [8-9].

EGFR-TKIs are a standard treatment for advanced NSCLC patients with EGFR mutations, and their role in the treatment of BM is less well established. Previous clinical studies found that EGFR TKIs [2,10], either in monotherapy or in combination with brain radiotherapy, had potential efficacy for NSCLC BM patients with EGFR mutations. The third generation of EGFR TKIs (e.g. AZD9291) is currently under development or in clinical trials to target mutant genes related with TKI tolerance [11], its interaction with the first generation EGFR TKIs is unclear and should be investigated in future.

We report herein a male NSCLC patient with BM who has achieved CR in BM and partial remission (PR) in lung lesion after 4 months' icotinib administration. Icotinib was continued for another 10 months after lung tumor resection until a liver metastasis was detected, and T790M mutation was observed. The patient later received AZD9291 combined with icotinib after TACE failed. He has been responding well to the combination treatment for 4 months.

Case presentation

The patient was a 59-year old man, who in October 2013, was diagnosed a lung cancer (NSCLC, cT3N2M1). He complained of having cough, headache, left limb paralysis, and gradual weakness for one month. The patient had a smoking history of 40 years and 2 years of hypertension. At the initial assessment in October 2013, the Karnofsky performance status was 80, the neurological test determined the left limb muscle strength of grade 4 (scores run from 0 to 5, where grade 0 is the most severe and grade 5 is normal), and an elevated carcinoembryonic antigen (CEA) was noted (13.56 μg/L, normal range 0–5 μg/L). According to findings of Computer Tomography (CT), primary lung lesion and a brain lesion was identified at the junctional zone between the temporal and parietal lobes of the left hemisphere (Figs. 1 A-B). A sample specimen, which was collected using transthoracic needle aspiration, was pathologically confirmed as an adenocarcinoma with a deletion of exon 19 of EGFR gene. The test also confirmed a negative result for T790M and ALK mutation. In October 2013, icotinib was administrated orally by 125 mg/d, three times daily.

Figure 1

Computer tomography (CT) scans of lung lesion and brain metastasis before and after icotinib treatment. (A and B) At diagnosis of the metastases (Oct 12, 2013); (C and D) After 16 days of icotinib therapy (Oct 28, 2013), revealing a good response to treatment; (E and F) After 47 days of icotinib treatment (Nov 26, 2013), revealing brain lesion completed resolved.

The patient reported a significant improvement of neurological symptoms after receiving icotinib treatment for 10 days and had a completed relief after 6 weeks. The only adverse effect was skin rash at 1 degree according to Common terminology criteria for adverse events 4.0 after 2 weeks’ administration. According to RECIST 1.1 (Figs.1 C-D), a significant improvement regarding partial response (PR) was observed, as evidenced by a 37.1% reduction in the size of lesion on average, and a quick absence in brain metastasis after 46 days of treatment (Figs.1 F). Considering the brain tumor had complete remission, we decided to monitor brain tumors by every 2 months using CT scan rather than a brain radiation therapy.

Given the good performance status, moderate increase of the lung lesions, and no evidence of BM recurrence, the patient underwent a left upper lobe resection on February 19, 2014. Similar pathological and molecular testing results were reported on the operative samples, which was EGFR exon 19 deletion and ALK-negative. Icotinib was interrupted for 10 days during perioperative period.

The lab results showed a continuous rise in CEA level, with a double increase observed after 6 months. Icotinib was increased to 250 mg tid and showed controlling effects on CEA for 8 months. CEA could not be controlled by doubled dose of icotinib, and PET/CT scan confirmed metastases in liver and lymph node lesions along the duodenum and inferior vena cava (Fig.2 A-B) on December 24, 2014. After a week, a liver lesion biopsy was performed to further confirmed a diagnosis of poorly differentiated metastatic adenocarcinoma and T790M mutation.

Figure 2

Abdominal computed tomography (CT) imaging of metastatic live lesion lymph node lesions before and after AZD9291 treatment. (A and B) At diagnosis of the metastases after administrating icotinib for 14 months (Dec 23, 2014); (C and D) After 2 months of transcatheter arterial chemoembolization, revealing disease progression (Mar 27, 2015); (E and F) After 20 days of combination treatment of icotinib and AZD9291, revealing a dramatic response (Apr 3, 2015).

TACE was prescribed to the patient on January 7, 2015 and Icotinib was administrated 3 days later with dose of 125 mg tid. Unfortunately, on March 24, 2015, a poor clinical response to the TACE was reported, along with new liver metastases (Fig.2 C-D).

The patient received AZD9291 20 mg twice daily on March 27, 2015, in combination icotinib treatment 125 mg tid. Three weeks later, we observed a significant reduction in liver lesions and lymph node lesions, and an average shrinkage of 35.1% in target lesion size (Fig.2 E-F). CEA gradually decreased, but remained above the normal range. The rationale behind a continuation of icotinib administration was that the brain lesion still was in completed remission with it. The combination of AZD9291 and icotinib continued to show acceptable efficacy and safety as of this paper’s writing for more than 4 months.

Ethical approval

The research related to human use has been complied with all the relevant national regulations, institutional policies and in accordance the tenets of the Helsinki Declaration, and has been approved by the authors’ institutional review board or equivalent committee.

Informed consent

Informed consent has been obtained from all individuals included in this study.

Discussion

EGFR TKIs, as suggested by previous phase II trials, were found to significantly improve the efficacy in treating brain metastasis among patients with EGFR-mutated NSCLC. The intracranial response rate was 52%–89% and the median progression-free survival was 6.6–23.2 months in EGFR mutant patients, [12-15] indicating that EGFR TKIs could be considered as an alternative to chemotherapy prior to radiotherapy in patients suffering from asymptomatic brain metastases. However, whether TKIs could delay or obviate the need of Whole-Brain Radiotherapy (WBRT) in symptomatic brain metastases remains unclear at this point. Several cases have been reported in patients with neurological symptoms treated with high doses of gefitinib or erlotinib to control their disease [16-19], suggesting that EGFR-TKIs may also play an important role in controlling symptomatic BM.

Icotinib is a small-molecule EGFR-TKI developed by a local pharmaceutical company in China. The efficacy and safety of icotinib have been verified to be comparable to gefitinib by a randomized phase III study as 2nd line therapy for NSCLC [20]. In 2015, the first line indication for NSCLC patients with EGFR mutation of icotinib was approved by the China Food and Drug Administration [21]. Several phase I and II studies of icotinib in treatment of BM have been published recently. Zhou et al reported that icotinib could be well tolerated at dose of 375mg tid/day concurrent with WBRT in a phase I study, and found that the mean icotinib cerebrospinal fluid (CSF) penetration rate was 4.04% (range: 1.23%–9.71%) [22]. A phase II study of icotinib combined with WBRT treatment found that the CSF concentration and penetration rate were 11.6 ± 9.1 ng/mL and 1.4 ± 1.1% respectively at a dose of icotinib 125mg tid. In the study, 10 patients with EGFR mutation had PFS and median overall survival times were 12.0 and 22.0 months, respectively [23]. The efficacy was consistent with the results of genfitinib and erlotinib published studies [12,15]. Zeng et al reported the efficacy of icotinib monotherapy for recurrent or progressive brain metastases after radiation in patients with end-stage NSCLC. 17 unselective patients, 9 patients had PR, 4 patients had SD and 4 patients had PD, and among 11 patients with EGFR mutation, 7 of 8 patients with 19DEL had PR [24]. The results suggested that intracranial metastasis tumors with 19 DEL were high sensitive to EGFR-TKIs as well. Zhang et al reported a patient with lung adenocarcinoma, with multiple lesions in the brain, controlled by icotinib more than 1 year with satisfactory health-related quality of life [25]. Can icotinib be used as a first-line single-drug treatment in BM patients with activating EGFR mutations? A phase III randomized controlled study is currently being conducted in BM patients with EGFR mutations in China to compare the PFS between the first line icotinib and WBRT treatments [26]. The results of this phase III study might solve the issue of selecting the first-line treatment for BM patients with EGFR mutations.

The present case demonstrated profound effects against BM within a short period of treatment. After complete remission of BM, the patient became a candidate for surgical resection of lung lesions and underwent an operation to achieve a complete removal of the lesions. The results suggested that a remarkable clinical response to icotinib among patients with BM from an EGFR mutated NSCLC, which further indicate an opportunity to surgically eradicate the residual tumors.

The main mechanism of acquired resistance to EGFR TKIs is T790M mutation, which accounts for two thirds of all post-TKI tumor samples [27]. Phase I–II studies of the third generation EGFR TKIs as AZD9291 and rociletinib have demonstrated potential therapeutic effects in NSCLC patients who failed in the first generation TKI treatment and subsequently showed T790M mutation [28,29]. Interestingly, due to the heterogeneity of the tumors, multiple site rebiopsies revealed T790M status was frequently distinct between CNS (especially CSF) and thoracic lesions in individual patients. Some patients even exhibited an intrathoracic T790M heterogeneity [30]. Based on these findings, it is warrant to investigate the combination of different generation TKIs utilized to overcome EGFR resistance or improve the efficacy. In this case, considering the consistent benefits of icotinib in treating BM, icotinib was not discontinued during the AZD 9291 treatment. The patient showed good response and acceptable tolerance to the combination treatment.

Conclusion

In conclusion, this case indicated an impressive clinical response to icotinib and multimodality therapy in treating BM with EGFR-mutated NSCLC, subsequently developed T790M in live metastasis and controlled by AZD9291. It also demonstrated an impressive clinical response to EGFR-TKIs and warranted a development of new strategies of multimodality therapy for IV stage NSCLC with EGFR sensitive mutations.