Keita Masuzawa

Amplification of EGFR Wild-Type Alleles in Non–Small Cell Lung Cancer Cells Confers Acquired Resistance to Mutation-Selective EGFR Tyrosine Kinase Inhibitors

EGFR-mutated lung cancers account for a significant subgroup of non-small cell lung cancers overall. Third-generation EGFR tyrosine kinase inhibitors (TKI) are mutation-selective inhibitors with minimal effects on wild-type EGFR. Acquired resistance develops to these agents, however, the mechanisms are as yet uncharacterized. In this study, we report that the Src-AKT pathway contributes to acquired resistance to these TKI. In addition, amplification of EGFR wild-type alleles but not mutant alleles was sufficient to confer acquired resistance. These findings underscore the importance of signals from wild-type EGFR alleles in acquiring resistance to mutant-selective EGFR-TKI. Our data provide evidence of wild-type allele-mediated resistance, a novel concept of acquired resistance in response to mutation-selective inhibitor therapy in cancer treatment. Cancer Res; 77(8); 2078-89. ©2017 AACR.

Comparison of detection methods of EGFR T790M mutations using plasma, serum, and tumor tissue in EGFR-TKI-resistant non-small cell lung cancer

Background Osimertinib, a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor, exerts remarkable effects against EGFR T790M resistance mutation-positive non-small cell lung cancer. Identifying T790M mutation by re-biopsy is essential before prescribing osimertinib. Tissue biopsy is the golden standard for this purpose, but several factors limit its success rate. The liquid biopsy with blood, using circulating tumor DNA, has been an alternative method. However, the true biological meaning and equivalence of liquid biopsy and tumor biopsy are still under investigation. Especially, the usefulness of serum samples to detect T790M mutation is not yet been known. Patients and methods We prospectively evaluated the sensitivity, specificity, and parallelism of the detection of EGFR mutations in tissue re-biopsy and liquid biopsy (plasma and serum), simultaneously, from June 2016 to May 2017. EGFR mutations in tumor re-biopsy were evaluated by COBAS ver2 and PNA-LNA PCR clamp method, and those in liquid biopsy were evaluated with COBAS ver2. Results Fifteen patients were enrolled. In 10 patients whose EGFR mutation was detected in liquid biopsy, the original EGFR mutation (exon 19 del or L858R) was detected in all patients. Detection of EGFR mutation by COBAS ver2 and by PNA-LNA method was almost the same in tissue re-biopsy. The detection rate of T790M was lower than that of the original EGFR mutation in liquid biopsy compared to that in tissue re-biopsy. The detection of T790M in serum exhibited a higher specificity (67%) and positive predictive value (50%) than that in plasma (50% and 40%, respectively). The detection sensitivity was similar in plasma and serum. Conclusion Plasma, serum, and tissue genotyping can have complementary roles for detecting EGFR-T790M using COBAS ver2. Repeated tests with different samples and different methods may improve accuracy of T790M detection and will lead to the maximum benefit for the patient.

Pharmacological and Structural Characterizations of Naquotinib, a Novel Third-Generation EGFR Tyrosine Kinase Inhibitor, in EGFR-Mutated Non–Small Cell Lung Cancer

Multiple epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI) have been developed to effectively inhibit EGFR-derived signals in non–small cell lung cancer (NSCLC). In this study, we assessed the efficacy of EGFR-TKIs, including a novel third-generation inhibitor naquotinib (ASP8273), in clinically relevant EGFR mutations, including L858R, exon 19 deletion, L858R+T790M, exon 19 deletion+T790M with or without a C797S mutation, and several exon 20 insertion mutations. Using structural analyses, we also elucidated the mechanism of activation and sensitivity/resistance to EGFR-TKIs in EGFR exon 20 insertion mutations. The efficacy of naquotinib in cells with L858R, exon 19 deletion and exon 19 deletion+T790M was comparable with that of osimertinib. Interestingly, naquotinib was more potent than osimertinib for L858R+T790M. Additionally, naquotinib and osimertinib had comparable efficacy and a wide therapeutic window for cells with EGFR exon 20 insertions. Structural modeling partly elucidated the mechanism of activation and sensitivity/resistance to EGFR-TKIs in two EGFR exon 20 insertion mutants, A767_V769dupASV and Y764_V765insHH. In summary, we have characterized the efficacy of EGFR-TKIs for NSCLC using in vitro and structural analyses and suggested the mechanism of activation and resistance to EGFR-TKIs of EGFR exon 20 insertion mutations. Our findings should guide the selection of appropriate EGFR-TKIs for the treatment of NSCLC with EGFR mutations and help clarify the biology of EGFR exon 20 insertion mutations. Mol Cancer Ther; 17(4); 740–50. ©2018 AACR.

Development of necrotizing myopathy following interstitial lung disease with anti-signal recognition particle antibody

A 72-year-old man was admitted due to dyspnea on exertion with interstitial shadows and elevated serum creatinine kinase (CK). Despite a close examination, which included magnetic resonance imaging (MRI), we could not diagnose myopathy. Prednisolone was administered and gradually tapered. One year later, anti-signal recognition particle (SRP) antibody was confirmed and he was re-admitted for hypoxemia with elevated CK. MRI revealed muscle edema and a histopathological examination of a muscle biopsy specimen showed necrotizing myopathy. Prednisolone, cyclosporine, and intravenous immunoglobulin were administered. Physicians should carefully monitor muscle symptoms and serum CK levels in cases of interstitial lung disease with anti-SRP antibodies.

Characterization of the efficacies of osimertinib and nazartinib against cells expressing clinically relevant epidermal growth factor receptor mutations

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) were developed to overcome EGFR T790M-mediated resistance to first- and second-generation EGFR-TKIs. Third-generation EGFR-TKIs, such as osimertinib and nazartinib, are effective for patients with the EGFR T790M mutation. However, there are no direct comparison data to guide the selection of a third-generation EGFR-TKI for patients with different EGFR mutations. We previously established an in vitro model to estimate the therapeutic windows of EGFR-TKIs by comparing their relative efficacies against cells expressing mutant or wild type EGFRs. The present study used this approach to characterize the efficacy of third-generation EGFR-TKIs and compare them with that of other EGFR-TKIs. Treatment efficacy was examined using human lung cancer-derived cell lines and Ba/F3 cells, which were transduced with clinically relevant mutant EGFRs. Interestingly, mutation-related differences in EGFR-TKI sensitivity were observed. For classic EGFR mutations (exon 19 deletion and L858R, with or without T790M), osimertinib showed lower IC50 values and wider therapeutic windows than nazartinib. For less common EGFR mutations (G719S or L861Q), afatinib showed the lowest IC50 values. For G719S+T790M or L861Q+T790M, the IC50 values of osimertinib and nazartinib were around 100 nM, which was 10- to 100-fold higher than those for classic+T790M mutations. On the contrary, osimertinib and nazartinib showed similar efficacies in cells expressing EGFR exon 20 insertions. The findings highlight the diverse mutation-related sensitivity pattern of EGFR-TKIs. These data may help in the selection of EGFR-TKIs for non-small cell lung cancer patients harboring EGFR mutations.

Invasive mucinous adenocarcinoma of the lung presenting as a large, thin-walled cyst: A case report and literature review

Invasive mucinous adenocarcinoma (IMA), formerly referred to as mucinous bronchioloalveolar carcinoma, is a rare variant form of invasive adenocarcinoma and is radiologically characterized by dense pneumonic consolidation, ground-glass opacity and nodules. By contrast, large, thin-walled cysts are rare. We herein report the case of a 75-year-old man with IMA presenting as a large, irregularly shaped cystic lesion. The histological diagnosis was based on specimens obtained during a bronchoscopy. The patient underwent lobectomy followed by anticancer chemotherapy for residual intrapulmonary metastases. Of note, the small metastatic nodules transformed into cystic lesions with thin walls and fused, forming a large, multiloculated cystic lesion. Typical pneumonic consolidation appeared in the pericystic parenchyma later during the clinical course. The available literature on this rare radiological manifestation was also reviewed and discussed. Clinicians should be aware of thin-walled cystic lesions as they may be an unusual radiological finding in IMA.

Suspected accelerated disease progression after discontinuation of nintedanib in patients with idiopathic pulmonary fibrosis: Two case reports

Rational: The efficacy of nintedanib, a multitarget receptor tyrosine kinase inhibitor, has been demonstrated in recent randomized controlled trials involving patients with idiopathic pulmonary fibrosis (IPF). However, accelerated disease progression after nintedanib discontinuation has never been reported. Patient concerns: We report 2 cases involving patients with a history of IPF who presented with respiratory deterioration at 3 weeks after the discontinuation of nintedanib therapy for IPF. Neither patient fulfilled the definition of “acute exacerbation of IPF” on unilateral computed tomography. Diagnoses: Accelerated disease progression after the discontinuation of nintedanib therapy for IPF. Interventions: One patient received steroid therapy. The other patient refused to undergo steroid therapy. Outcomes: The first patient showed that the affected lobe exhibited volume loss with traction bronchiectasis after receiving steroid therapy, and succumbed to pneumothorax after 3 months. The other patient was transferred to another hospital because of a decline in his general condition. Lessons: To our knowledge, this report is the first to document accelerated disease progression after the discontinuation of nintedanib therapy for IPF. Although the accurate mechanism remains unclear, the effects of nintedanib against vascular endothelial growth factor and platelet-derived growth factor receptor may play a role. Our findings suggest that physicians should carefully monitor patients with IPF after nintedanib discontinuation.

Sternoclavicular joint osteomyelitis extending to lung abscess complicated by Staphylococcal infective endocarditis

A 72-year-old man presented with the right chest pain. Two weeks before admission, he had visited an orthopedic clinic and was prescribed analgesics; however, the chest pain did not improve and the patient developed a productive cough. He had aortic regurgitation, but no history of trauma, diabetes mellitus, immunocompromised status, or drug abuse. Clinical examination revealed high-grade fever, and swelling and tenderness in the right sternoclavicular joint, with notable crepitance. Contrast-enhanced computed tomography revealed fluid accumulation in the right upper pulmonary lobe with an air-fluid level, and some air bubbles scattered along the right anterior chest wall (Fig. 1). T1-weighted contrast-enhanced magnetic resonance imaging (MRI) with fat suppression revealed bone erosion around the right sternoclavicular joint, with surrounding edema (Fig. 2A), as well as bone marrow edema along with cortical irregularity of the medial end of the right clavicle (Fig. 2B). Blood and sputum cultures were positive for methicillin-sensitive Staphylococcus aureus. Transesophageal echocardiography revealed a vegetation in the aortic valve. Consequently, the diagnosis of lung abscess and sternoclavicular joint osteomyelitis, complicated by infective endocarditis was made. Antimicrobial therapy for 8 weeks resulted in clinical improvement and complete disappearance of the cavitary lesions. At initial diagnosis, it was unclear whether the initiating event was infective endocarditis, primary pulmonary infection, or sternoclavicular joint infection. However, we believe an inflammatory process spreading from the right sternoclavicular joint, with osteomyelitis, extending along the chest wall to the right upper pulmonary lobe, resulted in the lung abscess. This was based on the antecedent history of right chest pain, pulmonary symptoms, and MRI findings. Sternoclavicular joint osteomyelitis, mainly caused by Staphylococcus spp., occurs in immunocompromised hosts, but rarely in healthy adults [1]. It leads to serious complications, such as chest wall and lung abscess, mediastinitis, and pyomyositis, with increased mortality [2–4]. Surgical management is often required [5]; however, in this case, long-term antimicrobial therapy was initiated due to complications arising from Staphylococcal infective endocarditis. Successful treatment without surgery was achieved. Sternoclavicular joint osteomyelitis should be considered in patients with lung abscess in the upper lobes, complicated with chest pain.

Abstract 2099: In vitro characterization of the effect of nazartinib against non-small cell lung cancer activating clinically relevant EGFR mutants

Purpose: Multiple EGFR-TKIs are available and under development to treat patients with lung cancer harboring EGFR mutations. Nazartinib is one of the 3rd generation EGFR-TKIs targeting EGFR T790M as well as common mutations such as L858R and exon 19 deletions. Today, there is no clear guideline regarding which EGFR-TKIs should be used for which mutations. The purpose of this study is to clarify which EGFR-TKIs including nazartinib are best for each EGFR mutation, especially exon 20 insertion mutations using in vitro modeling. Experimental design: We evaluated drug sensitivity and downstream signaling of human lung cancer cell lines (PC9, H3255, H1975, PC9ER, BID007) and Ba/F3 cells harboring multiple types of EGFR mutations for 1st- (erlotinib), 2nd- (afatinib) and 3rd- (osimertinib and nazartinib) generation EGFR-TKIs by MTS assay and western blotting. An in vitro model of mutation specificity was created by calculating the ratio of IC50 values between mutated and wild type EGFRs. Results: The model of mutation specificity identified a wide therapeutic window of each EGFR-TKIs for exon 19 deletions and L858R. On the other hand, osimertinib and nazartinib have wide therapeutic window for T790M positive mutations in human cell lines and Ba/F3 cells. In human cell lines and Ba/F3 cells harboring exon 19 deletions or L858R, afatinib dramatically inhibited the phosphorylation of EGFR, AKT, and ERK. Afatinib and 3rd generation EGFR-TKIs, osimertinib and nazartinib, effectively inhibited the phosphorylation of EGFR, AKT, and ERK in T790M positive cells. For EGFR exon 20 insertion mutations, althogh afatinib, osimertinib and nazartinib effectively inhibited the phosphorylation of EGFR, AKT, and ERK in several exon 20 insertion mutations, osimertinib and nazartinib were potent and presented a wide therapeutic window. Conclusion: Nazartinib as well as osimertinib has wide therapeutic windows for exon 19 deletions, L858R, T790M and some exon 20 insertions . Citation Format: Keita Masuzawa, Hiroyuki Yasuda, Toshiyuki Hirano, Shigenari Nukaga, Hanako Hasegawa, Junko Hamamoto, Katsuhiko Naoki, Kenzo Soejima, Tomoko Betsuyaku. In vitro characterization of the effect of nazartinib against non-small cell lung cancer activating clinically relevant EGFR mutants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2099. doi:10.1158/1538-7445.AM2017-2099