Transformation to small-cell lung cancer following treatment with EGFR tyrosine kinase inhibitors in a patient with lung adenocarcinoma

Clinical Efficacy and Safety of First- or Second-Generation EGFR-TKIs after Osimertinib Resistance for EGFR Mutated Lung Cancer: A Prospective Exploratory Study

BACKGROUND

Osimertinib monotherapy is a common treatment for epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC); however, standard treatment strategies for acquired resistance to this drug have not been established. In addition, the clinical significance of first-generation (1G) or second-generation (2G) EGFR-tyrosine kinase inhibitors (TKI) in patients with EGFR-mutant NSCLC and osimertinib resistance has not yet been fully evaluated.

OBJECTIVE

We aimed to conduct a prospective multicenter observational study to evaluate the efficacy and safety of 1G and 2G EGFR-TKIs after the development of osimertinib resistance.

METHODS

Patients with EGFR-mutant NSCLC who received 1G or 2G EGFR-TKIs after developing resistance to osimertinib monotherapy were prospectively assessed at eight institutions in Japan. The primary endpoint was progression-free survival (PFS).

RESULTS

A total of 29 patients with advanced or recurrent EGFR-mutant NSCLC were analyzed. The objective response and disease control rates were 6.9% (2/29) and 58.6% (17/29), respectively. The median PFS was 1.9 months [95% confidence interval (CI): 1.3-5.3]. There was no significant difference in PFS between the 1G and 2G EGFR-TKI groups (3.7 versus 1.5 months, log-rank test p = 0.20). However, patients with normal cytokeratin 19 fragment (CYFRA 21-1) and pro-gastrin-releasing peptide (ProGRP) levels experienced longer PFS than those with elevated CYFRA 21-1 and/or ProGRP (5.5 versus 1.3 months, log-rank test p < 0.001).

CONCLUSION

Administration of 1G or 2G EGFR-TKIs after the development of osimertinib resistance has limited efficacy in patients with EGFR-mutant NSCLC. Moreover, normal CYFRA 21-1 and ProGRP levels could be promising indicators for 1G and 2G EGFR-TKI administration after osimertinib resistance development.

TRIAL REGISTRATION NUMBER

UMIN000044049.

Current Knowledge of Small Cell Lung Cancer Transformation from Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer related death, and is divided into two major histological subtypes, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Histological transformation from NSCLC to SCLC has been reported as a mechanism of treatment resistance in patients who received tyrosine kinase inhibitors (TKIs) targeting EGFR, ALK and ROS1 or immunotherapies. The transformed histology could be due to therapy-induced lineage plasticity or clonal selection of pre-existing SCLC cells. Evidence supporting either mechanism exist in the literature. Here, we discuss potential mechanisms of transformation and review the current knowledge about cell of origin of NSCLC and SCLC. In addition, we summarize genomic alterations that are frequently observed in both "De novo" and transformed SCLC, such as TP53, RB1 and PIK3CA. We also discuss treatment options for transformed SCLC, including chemotherapy, radiotherapy, TKIs, immunotherapy and anti-angiogenic agents.

Other markers of medullary thyroid cancer, not only calcitonin

BACKGROUND

Medullary thyroid cancer (MTC) is a rare neuroendocrine tumor originating from parafollicular C-cells. It represents 2% of all thyroid malignancies and 0.4-1.4% of all thyroid nodules. MTC has a variable clinical course, with complete remission often difficult to achieve. An early diagnosis is still crucial in MTC management, enabling a radical surgical treatment, the only chance for curing the patient. Calcitonin (Ct) is a very sensitive MTC tumor marker in patients with thyroid nodules, although Ct-negative MTCs have been described, but not all clinical guidelines recommend the Ct routine measurement in thyroid nodules because of the absolute low prevalence of MTC in the general population and the consequent scarce positive predictive value of Ct. Moreover, the specificity of moderately high Ct levels is not high. Thus, the scientific community has been investigating the possible role of other tumor markers for MTC diagnosis and prognosis.

AIM OF THE REVIEW

The present review is an attempt to summarize the knowledge available today on the role of other serum markers for MTC alternative to Ct.

CONCLUSIONS

At present, literature data does not seem solid enough yet to establish effective flowcharts in evaluating a thyroid nodule for MTC, involving alternative serum markers, particularly in cases of moderately high CT levels. MTC is a rare diagnosis in thyroid nodules, and this makes the evaluation of any tumor serum marker accuracy problematic. More extensive and prospective studies are needed to shed more light on this intriguing challenge.

[Two Cases of TKI-resistant Small Cell Lung Cancer Transformation in Advanced Adenocarcinoma and Literature Review]

Treatment of advanced non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation with EGFR-tyrosine kinase inhibitors (EGFR-TKIs) can achieve good disease control, but it will inevitably produce drug resistance. About 3%-10% of the resistance mechanism is small cell transformation. Two cases of stage IV lung adenocarcinoma with EGFR mutation were reported and the disease was controlled after EGFR-TKIs treatment. In case 1, progression-free survival (PFS) before small cell carcinoma transformation was 16 months, and in case 2, PFS before small cell carcinoma transformation was 24 months. Subsequent biopsy after disease progression indicated a shift to small cell lung cancer. Case 1 PFS after small cell carcinoma transformation was 6 months, and case 2 PFS after small cell carcinoma transformation was 8 months, and overall survival (OS) was 36 months, which significantly prolonged the patient's survival. At the same time, the literature of such drug resistance mutations was reviewed. For patients with advanced NSCLC with sensitive mutations, it is necessary to conduct secondary histopathological tests after TKIs treatment resistance, and select subsequent treatment according to different resistance mechanisms for the whole course of disease management.
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Morphologic-Molecular Transformation of Oncogene Addicted Non-Small Cell Lung Cancer

Patients with non-small cell lung cancer, especially adenocarcinomas, harbour at least one oncogenic driver mutation that can potentially be a target for therapy. Treatments of these oncogene-addicted tumours, such as the use of tyrosine kinase inhibitors (TKIs) of mutated epidermal growth factor receptor, have dramatically improved the outcome of patients. However, some patients may acquire resistance to treatment early on after starting a targeted therapy. Transformations to other histotypes—small cell lung carcinoma, large cell neuroendocrine carcinoma, squamous cell carcinoma, and sarcomatoid carcinoma—have been increasingly recognised as important mechanisms of resistance and are increasingly becoming a topic of interest for all specialists involved in the diagnosis, management, and care of these patients. This article, after examining the most used TKI agents and their main biological activities, discusses histological and molecular transformations with an up-to-date review of all previous cases published in the field. Liquid biopsy and future research directions are also briefly discussed to offer the reader a complete and up-to-date overview of the topic.

Small cell lung cancer transformation: From pathogenesis to treatment

Small cell lung cancer (SCLC) is a type of neuroendocrine tumor with high malignancy and poor prognosis. Besides the de novo SCLC, there is transformed SCLC, which has similar characteristics of pathological morphology, molecular characteristics, clinical manifestations and drug sensitivity. However, de novo SCLC and transformed SCLC have different pathogenesis and tumor microenvironment. SCLC transformation is one of the mechanisms of resistance to chemotherapy, immunotherapy, and targeted therapy in NSCLC. Two hypotheses have been used to explain the pathogenesis of SCLC transformation. Although SCLC transformation is not common in clinical practice, it has been repeatedly identified in many small patient series and case reports. It usually occurs in epidermal growth factor receptor (EGFR) mutant lung adenocarcinoma after treatment with tyrosine kinase inhibitors (TKIs). SCLC transformation can also occur in anaplastic lymphoma kinase (ALK)-positive lung cancer after treatment with ALK inhibitors and in wild-type EGFR or ALK NSCLC treated with immunotherapy. Chemotherapy was previously used to treat transformed SCLC, yet it is associated with an unsatisfactory prognosis. We comprehensively review the advancements in transformed SCLC, including clinical and pathological characteristics, and the potential effective treatment after SCLC transformation, aiming to give a better understanding of transformed SCLC and provide support for clinical uses.

Serum NSE is Early Marker of Transformed Neuroendocrine Tumor After EGFR-TKI Treatment of Lung Adenocarcinoma

Background

Transformation to a lung neuroendocrine tumor (LNET) is a mechanism of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI). Serum neuron-specific enolase (NSE) is a useful marker in the detection of LNET. Therefore, we explored the clinical significance of serum NSE levels in the detection of transformed neuroendocrine tumors after EGFR-TKI therapy.

Methods

We report a cohort of 5 cases in our treatment group. The characteristics of the patients, pathological diagnoses, immunohistochemistry with molecular detection, laboratory examination, and treatment histories are analyzed. The tumor markers of serum NSE were analyzed. Additionally, we reviewed the publications reporting the tumor markers before and after LNET transformation during EGFR-TKI therapy.

Results

Most patients are female (3/5), aged <60 years old (4/5), nonsmokers (4/5) and harbor the EGFR 19 exon deletion (4/5). The median time of LNET transformation was 19 months (range: 12–31 months). The clinical characteristics were similar to those reported in previous studies. Laboratory examination revealed an increased NSE level before the LNET is defined. Sixteen publications were reviewed. Of those, 86.67% (13/15) publications showed an increased level of NSE when the LNET transformation was defined.

Conclusion

Adenocarcinoma tumors in non-smokers, young patients harboring the EGFR 19 exon deletion tended to transform to LNETs after EGFR-TKI therapy. Combining our findings and a review of the literature, we suggest that serum NSE may be a useful tumor marker to predict neuroendocrine tumor transformation.

Outcomes in Patients With Lung Adenocarcinoma With Transformation to Small Cell Lung Cancer After EGFR Tyrosine Kinase Inhibitors Resistance: A Systematic Review and Pooled Analysis

Background

Lung adenocarcinoma can transform into small-cell lung cancer (SCLC) when resistance to tyrosine kinase inhibitors (TKIs) develops. Approximately 3% to 10% of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) could transform to SCLC. This phenomenon has been described in several case reports and small patient series. However, the characteristics and treatment outcomes of this population have not been comprehensively reported, and their clinical course is poorly characterized.

Methods

We performed a systematic review of the published literature to summarize the clinical and pathological features and prognosis of the reported cases and analyzed the demographics, disease features, and outcomes.

Results

A total of 72 patients (50 females and 22 males) initially diagnosed with lung adenocarcinoma were included. EGFR mutations included 19-deletion (75%), L858R (22%), and G719X (3%). All patients received EGFR-TKIs before SCLC transformation. The median time from diagnosis to transformation was 20.5 months (95% CI, 15.45 to 26.55 months). Of the 67 patients with post-translational gene test results, 58 maintained their EGFR mutation, and only 1 of 18 with prior T790M positivity retained T790M mutation. After the pathological transformation, both conventional chemotherapy regimen and chemotherapy combined targeted therapy yielded high response rates. The disease control rate of first-line therapy after transformation was 76%, while the objective response rate was 48%. The median overall survival (OS) since diagnosis was 27 months (95% CI, 22.90 to 31.10 months), whereas median OS since SCLC transformation was 8.5 months (95% CI, 5.50 to 11.60 months).

Conclusion

The prognosis of transformed SCLC is worse than primary SCLC. The response rate to conventional chemotherapy was high. However, the progression-free survival and OS after transformation were short and the prognosis was poor with first-line therapies. New therapies are needed in the management of transformed SCLC.

Clinicopathological features of patients with transformation from EGFR mutant lung adenocarcinoma to small cell lung cancer

Background

Recently, an increasing number of cases with transformation from lung adenocarcinoma to small cell lung cancer (SCLC) have been identified, but few studies have investigated the clinical, pathological as well as molecular characteristics of these cases. This study aimed to summarize and analyze these features.

Methods

We retrospectively collected data including clinical information, laboratory examination results, radiological and pathological findings of ten patients, who were confirmed to undergo SCLC transformation following treatment from January 2014 to January 2020.

Results

The median time of treatment (targeted agents) was 14 months, and the median time interval of SCLC transformation following treatment was 24 months. Immunohistochemical indicators after transformation showed positive thyroid transcription factor 1 (TTF1), synaptophysin (Syn), CD56, and AE1/AE3, highly expressed Ki67, as well as negative programmed cell death-ligand 1 (PD-L1). Compared with the patients who received targeted therapy first, those patients who received chemotherapy followed by targeted therapy presented longer time intervals to transformation (36 vs. 22 months). Genetic testing after transformation showed that eight patients still maintained the original epidermal growth factor receptor (EGFR) mutation types. The median progression-free survival (PFS) after transformation was 5 months, and the median survival time after transformation was 10 months in seven patients who died.

Conclusions

Lung adenocarcinomas, once transformed to SCLC, progress rapidly and lead to poorer prognosis. After transformation, most of the patients maintain the original EGFR mutation types.

Case report: TP53 and RB1 loss may facilitate the transformation from lung adenocarcinoma to small cell lung cancer by expressing neuroendocrine markers

INTRODUCTION

Transformation from lung adenocarcinoma (LUAD) to small cell lung cancer (SCLC) is one of the mechanisms responsible for acquired EGFR-TKIs resistance. Although it rarely happens this event determines a rapid disease deterioration and needs specific treatment.

PATIENT AND METHOD

We report a case of 75-year-old LUAD female with a p.L858R mutation in Epidermal Growth Factor Receptor (EGFR) who presented with SCLC transformation after responding to first line osimertinib treatment for only 6 months. To understand the underlying molecular mechanism, we retrospectively sequenced the first (LUAD) and the second (SCLC) biopsy using a 56 multi-gene panel. Immunohistochemistry (IHC) staining and Fluorescence In Situ Hybridization (FISH) was applied to confirm the genetic aberrations identified.

RESULTS

EGFR p.E709A and p.L858R, Tumor Protein p53 (TP53) p.A159D and Retinoblastoma 1 (RB1) c.365-1G>A were detected in both the diagnostic LUAD and transformed SCLC samples. A high copy number gain for Proto-Oncogene C-Myc (MYC) and a Phosphoinositide 3-Kinase Alpha (PIK3CA) p.E545K mutation were found in the transformed sample specifically. Strong TP53 staining and negative RB1 staining were observed in both LUAD and SCLC samples, but FISH only identified MYC amplification in SCLC tissue.

CONCLUSION

We consider the combined presence of MYC amplification with mutations in TP53 and RB1 as drivers of SCLC transformation. Our results highlight the need to systematically evaluate TP53 and RB1 status in LUAD patients to offer a different therapeutic strategy.

Novel ETV1 mutation in small cell lung cancer transformation resistant to EGFR tyrosine kinase inhibitors

Background

Non-small cell lung cancer (NSCLC) patients harboring mutations in the epidermal growth factor receptor (EGFR) gene respond dramatically to EGFR tyrosine kinase inhibitors (TKIs). However, these patients inevitably develop acquired resistance to EGFR-TKIs. Among them, small cell lung cancer (SCLC) transformation is a relatively rare mechanism.

Methods

We used a 639 cancer-relevant gene panel to detect genetic differences in tissues before and after EGFR-TKIs resistance caused by SCLC transformation. In vitro experiments were conducted to study the role of ETS variant transcription factor 1 (ETV1) on SCLC transformation and EGFR-TKIs resistance.

Results

We present two EGFR-mutant lung adenocarcinoma (LUAD) patients. One patient, with EGFR exon 19 deletion (Ex19del), accepted first-line gefitinib treatment and then received osimertinib treatment due to acquisition of an EGFR-T790M mutation. A novel ETV1 mutation (p.P159S) was detected in the SCLC tissue after osimertinib resistance when not coexisting with T790M. The other patient harbored an EGFR exon 21 mutation (p.L858R), and had a long-lasting response to first-line gefitinib, and then transformed to SCLC after TKI resistance. A previously unreported ETV1 mutation (p.E462Q) was detected in the SCLC tissue. In vitro, ETV1 p.E462Q and p.P159S mutations participated in neuroendocrine differentiation by inducing the expression of achaete-scute homolog 1 (ASCL1) and promoting the proliferation of H69 cells. ETV1 p.E462Q and p.P159S mutations were also resistant to gefitinib and osimertinib after introduction into H358 cells.

Conclusions

Novel ETV1 p.E462Q and p.P159S mutations were found in the SCLC tissues of TKIs-resistant LUAD patients, providing a new understanding of ETV1 involvement in acquired resistance to EGFR-TKIs via SCLC transformation.

Epithelial cell plasticity: breaking boundaries and changing landscapes

Epithelial tissues respond to a wide variety of environmental and genotoxic stresses. As an adaptive mechanism, cells can deviate from their natural paths to acquire new identities, both within and across lineages. Under extreme conditions, epithelial tissues can utilize "shape-shifting" mechanisms whereby they alter their form and function at a tissue-wide scale. Mounting evidence suggests that in order to acquire these alternate tissue identities, cells follow a core set of "tissue logic" principles based on developmental paradigms. Here, we review the terminology and the concepts that have been put forward to describe cell plasticity. We also provide insights into various cell intrinsic and extrinsic factors, including genetic mutations, inflammation, microbiota, and therapeutic agents that contribute to cell plasticity. Additionally, we discuss recent studies that have sought to decode the "syntax" of plasticity-i.e., the cellular and molecular principles through which cells acquire new identities in both homeostatic and malignant epithelial tissues-and how these processes can be manipulated for developing novel cancer therapeutics.

Whole exome sequencing (WES) analysis of transformed small cell lung cancer (SCLC) from lung adenocarcinoma (LUAD)

Background

Histologic transformation of non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is a rare mechanism of acquired resistance to epidermal growth factor receptor (EGFR)-targeted tyrosine kinase inhibitors. However, the SCLC transformation has also been observed in non-

EGFR

mutant NSCLC. In these cases, whether SCLC initially co-exists with NSCLC or originates from initial NSCLC remains to be determined.

Methods

Whole exome sequencing was performed on 10 samples from 5 patients with SCLC transformation from lung adenocarcinoma (LUAD), a main subtype of NSCLC. Somatic mutations and copy number variations (CNVs) were analyzed to explore the differences between initial LUAD and transformed SCLC, as well as the origin of transformed SCLC.

Results

After SCLC transformation, the mutation spectrum changed, with decreased C>T and increased C>A. Compared with initial LUAD, the CNV burden of transformed SCLC was greatly increased (39.0 vs. 61.1, Wilcoxon P=0.4). The higher the CNV burden of LUAD, the shorter the time to SCLC transformation was observed to be; and the higher the CNV burden of transformed SCLC, the shorter the overall survival (OS) after transformation. Clonal evolution analysis showed different clonal components between initial LUAD and transformed SCLC.

Conclusions

The transformation of LUAD into SCLC may be promoted by CNV events rather than mutational events. CNV burden was associated with the time to SCLC transformation and with the OS of patients following SCLC transformation. Transformed SCLC did not evolve directly from the initial LUAD but branched off from LUAD before the time of initial diagnosis.

The efficacy and safety of osimertinib in treating nonsmall cell lung cancer: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is the primary treatment in treating with EGFR mutant nonsmall cell lung cancer (NSCLC). This systematic review and meta-analysis aimed to evaluate the efficacy and safety of the third-generation EGFR-TKI, osimertinib, and summarize the risk factors associating with outcome after osimertinib treatment.

METHOD

The Ovid Medline, Embase, Cochrane Library, and Pubmed were systematically searched due to December 10, 2019. All the studies that mentioned the overall survival (OS), progression-free survival (PFS), treatment response, and adverse events (AEs) of osimertinib were involved in our study. Hazard ratio (HR) with 95% confidence intervals was used for comparing OS and PFS.

RESULT

A total of 47 studies were included in the systematic review, of which 14 studies were used to compare the efficacy between osimertinib and other EGFR-TKI or chemotherapy. Patients treating with osimertinib favors a higher OS and PFS in all the patients (HR = 0.56 and 0.38, P < .001, respectively), and in subgroup analysis, compared with other treatments. Median 55% T790 mutant NSCLC patients might experience partial response, and 25% of patients remained as stable disease. The incidence of severe AE ranged from 0% to 5%, and the most common severe AE was pneumonia (3%). Patients with the T858R mutation may have a better OS than Del 19 mutation (HR = 0.55, P = .037), while patients who have a smoking history may have a higher risk of progression than never-smoker patients (HR = 1.47, P = .028).

CONCLUSION

Osimertinib has an impressive antitumor activity compared with prior EGFR-TKI and chemotherapy with an acceptable response and tolerable AEs. EGFR mutation type and smoking status were the risk factors for mortality and progression in NSCLC patients.

ProGRP AS A NOVEL BIOMARKER FOR THE DIFFERENTIAL DIAGNOSIS OF MEDULLARY THYROID CARCINOMA IN PATIENTS WITH THYROID NODULES

Objective: To investigate the release of progastrin-releasing peptide (ProGRP) in patients with thyroid nodules and the value of ProGRP in fine-needle aspirate washout fluid (FNA-ProGRP) in the differential diagnosis between medullary thyroid carcinoma (MTC) and non-MTC thyroid nodules. Methods: We investigated 2,446 healthy persons and 212 patients with 235 thyroid nodules. They were classified into healthy, nodular goiter, chronic thyroiditis, thyroid follicular neoplasm, papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. The serum ProGRP and FNA-ProGRP were measured. Results: The serum ProGRP median concentration in MTC was 124.40 pg/mL, significantly higher than in other groups. The cutoff value of serum ProGRP was 68.30 pg/mL, leading to 53.85% sensitivity, 96.98% specificity, and 0.51 kappa value in MTC. The FNA-ProGRP median concentration in MTC nodules was 2,096.00 pg/mL, significantly higher than in other groups. A receiver operating characteristic analysis of MTC nodules and non-MTC nodules indicated that the cutoff value was 22.77 pg/mL, leading to 94.12% sensitivity, 98.27% specificity, and 0.85 kappa value. Conclusion: FNA-ProGRP measurement could be served as an ancillary method for the differential diagnosis between MTC and non-MTC thyroid nodules. Abbreviations: CEA = carcinoembryonic antigen; CT = calcitonin; FNAC = fine-needle aspiration cytology; FNA-CT = calcitonin in fine-needle aspirate washout fluid; FNA-ProGRP = ProGRP in fine-needle aspirate washout fluid; MTC = medullary thyroid carcinoma; ProGRP = progastrin-releasing peptide; SCLC = small-cell lung cancer; TM = tumor marker.

Pathological transition as the arising mechanism for drug resistance in lung cancer

Despite the tremendous efforts for improving therapeutics of lung cancer patients, its prognosis remains disappointing. This can be largely attributed to the lack of comprehensive understanding of drug resistance leading to insufficient development of effective therapeutics in clinic. Based on the current progresses of lung cancer research, we classify drug resistance mechanisms into three different levels: molecular, cellular and pathological level. All these three levels have significantly contributed to the acquisition and evolution of drug resistance in clinic. Our understanding on drug resistance mechanisms has begun to change the way of clinical practice and improve patient prognosis. In this review, we focus on discussing the pathological changes linking to drug resistance as this has been largely overlooked in the past decades.

Unexpected favorable outcome to etoposide and cisplatin in a small cell lung cancer transformed patient: a case report

Patients with epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer can benefit significantly from EGFR tyrosine-kinase inhibitors (TKIs) treatment, but almost every patient will inevitably develop resistance. The transformation to small cell lung cancer (SCLC) has been described as an EGFR-TKI resistance often associated with aggressive clinical course and poor prognosis. In this study, we report an unexpected favorable response to etoposide and cisplatin (EP) from an EGFR-mutant patient who developed SCLC transformation at disease progression after the administration of erlotinib with a progression-free survivalof 7.7 months. At disease progression (PD) after erlotinib, rebiopsy showed typical SCLC histology accompanied by positive expressions of CD56, TTF-1, CK7, and synaptophysin. Subsequently, he was switched to standard SCLC treatment regimen EP in combination with erlotinib due to the retention of EGFR 19 del and achieved PR four cycles after the treatment. His disease progressed again 7.7 months after the initiation of EP treatment, with an enlargement of both primary and metastatic lesions. Collectively, this case illustrated the transformation from adenocarcinoma to SCLC and the subsequent durable benefit from standard treatment for SCLC.

Transformation of lung adenocarcinoma to small cell lung carcinoma in the setting of tyrosine kinase inhibitor therapy: Cytological approach of a clinically challenging phenomenon

Lung adenocarcinoma transformation into small cell lung carcinoma is a well-established phenomenon. Several reports and studies have been published, describing the clinical and pathological clues to detect this transformation. This article will discuss the cytological aspect of this entity, highlighting pertinent features, to bring more attention to the existence of this transformation into the cytopathology practice.

Overcoming acquired resistance of gefitinib in lung cancer cells without T790M by AZD9291 or Twist1 knockdown in vitro and in vivo

The T790M mutation is recognized as a typical mechanism of acquired resistance to first generation of epithermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib in non-small cell lung cancer (NSCLC) patients who are commonly treated by third generation of EGFR-TKI AZD9291 (osimertinib). However, the therapeutic strategy for overcoming acquired resistance to EGFR-TKIs in NSCLC patients without T790M remains to be definitively determined. In the present study, gefitinib-resistant H1650 (H1650GR) or AZD9291-resistant H1975 (H1975AR) was generated by exposing NSCLC cell line H1650 or H1975 to progressively increased concentrations of gefitinib or AZD9291 over 11 months. The cytotoxic effects of gefitinib or AZD9291 in vitro were evaluated via the half maximal inhibitory concentrations (IC50s) determined by the MTT assay. IC50 of gefitinib in H1650GR (50.0 ± 3.0 µM) significantly increased compared with H1650 (31.0 ± 1.0 µM) (p < 0.05). Similarly, the IC50 of AZD9291 in H1975AR (10.3 ± 0.9 µM) significantly increased compared with H1975 (5.5 ± 0.6 µM) (p < 0.05). However, IC50 of AZD9291 on H1650GR (8.5 ± 0.5 µM) did not increase compared with H1650 (9.7 ± 0.7 µM). On the other hand, IC50 of AZD9291 on gefitinib-resistant A549 (A549GR established in our previous study) (12.7 ± 0.8 µM) was significantly increased compared with A549 (7.0 ± 1.0 µM) (p < 0.05). AZD9291 induced caspase 3/7 activation in A549, H1650, and H1650GR, but not in A549GR. Western blot analyses showed that p-Akt played a key role in determining the sensitivities of A549, A549GR, H1650, and H1650GR to gefitinib or AZD9291. Additionally, increased expression of Twist1 was observed in all cells with acquired EGFR-TKI resistance and knockdown of Twist1 by shRNA was found to significantly enhance the sensitivity of A549GR to gefitinib or AZD9291 via reversing epithelial-mesenchymal transition and downregulating p-Akt, but not of H1975AR to AZD9291. The enhanced cytotoxic effect of AZD9291 on A549GR by Twist1 knockdown in vitro was further validated by in vivo studies which showed that Twist1 knockdown could lead to significantly delayed tumor growth of A549GR xenograft with increased sensitivity to AZD9291 treatment in nude mice without any observed side toxic effects. In summary, our study demonstrated that the mechanisms of acquired resistance in different NSCLC cell lines treated by even the same EGFR-TKI might be quite different, which provide a rationale for adopting different therapeutic strategies for those NSCLC patients with acquired EGFR-TKI resistance based on different status of heterogeneous mutations.

ProGRP as early predictive marker of non-small-cell lung cancer to small-cell lung cancer transformation after EGFR-TKI treatment

We report a case of non-small-cell lung cancer (NSCLC) to small-cell lung cancer (SCLC) transformation after epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment. The patient was a man who diagnosed with EGFR-mutant advanced NSCLC. After he was introduced afatinib, his tumor had been reduced by the treatment. However, plasma pro-gastrin-releasing peptide (ProGRP) became higher with disease progression, and SCLC was detected at the second biopsy. It is suggested that elevation of plasma ProGRP level before EGFR-TKI therapy is useful for predicting EGFR-mutant NSCLC to SCLC transformation.

Role of Cytomorphology in the Era of Liquid Biopsy

In the late stages of non-small cell lung cancer, the detection of sensitizing mutations of the epidermal growth factor receptor (EGFR) is mandatory to select patients' treatment with first- or second-generation tyrosine kinase inhibitors (TKIs). In patients showing progressive disease, the assessment of the EGFR exon 20 resistance point mutation p.T790M is required for third-generation TKI administration. However, molecular analysis does not capture all the different mechanisms of resistance against these molecules. A variety of morphological changes associated with acquired resistance have also been described. Since an altered morphology may be the only clue to acquired resistance, cytopathology still plays a relevant role in this setting. In this comprehensive review, we have focused on the relevance of squamous cell carcinoma, small cell lung cancer and large-cell neuroendocrine carcinoma transitions from adenocarcinoma resistant to TKIs.

The clinicopathologic of pulmonary adenocarcinoma transformation to small cell lung cancer

Transformation to small cell lung cancer (SCLC) is one of the mechanisms of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, it is uncertain how it works and there is no standard treatment after the transformation. In this study, 7 patients with transformation of SCLC from advanced lung adenocarcinoma (ADC) were analyzed retrospectively and the clinical pathology, imaging characteristics and treatment were analyzed.We identified 7 patients with primary lung ADC that showed transformation to SCLC on second biopsy during a 6-year period. Clinicopathologic information was analyzed and EGFR mutation results were performed in initial biopsy samples.Seven patients showed transformation from ADC to SCLC, of which 6 patients were 19 del EGFR mutation, only 1 patient is L858R mutations. The imaging forms did not have the typical imaging features of primary SCLC. All patients underwent etoposide and carboplatin (EC) regimen chemotherapy after pathological transformation. However, the response rate of EC was less than primary small cell lung cancer. One of the patients was receiving EC for 4 cycles. After chemotherapy the patients performed radiation therapy and finally with erlotinib maintains treatment, the progress free survival (PFS) was more than 12 months.NSCLC can acquire a neuroendocrine phenotype with EGFR-TKI treatment. The transmutation is more common in 19del mutation patients. A comprehensive treatment based on EC regimen chemotherapy and the maintenance with EGFR-TKI is likely to be the appropriate treatment for these patients.

Overcoming T790M mutant small cell lung cancer with the third-generation EGFR-TKI osimertinib

A large number of EGFR mutant non-small cell lung cancer patients primordially benefit from first-line treatment with first-generation EGFR-tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. However, multiple acquired resistance mechanisms have been described that limit the clinical efficacy of first-generation EGFR-TKIs. Herein, we report a rare case of lung adenocarcinoma harboring an EGFR exon 19-deletion mutation before the administration of target therapy. This patient acquired resistance to first-generation EGFR-TKIs through small cell lung cancer (SCLC) transformation accompanied by the T790M mutation. Unexpectedly, this SCLC patient maintained a sensitive response to the third-generation EGFR-TKI osimertinib. This special case may indicate that osimertinib represents an effective target drug for SCLC patients who harbor an EGFR T790M mutation.

Histologic transformation of non-small-cell lung cancer in brain metastases

BACKGROUND

Treatment strategies differ substantially for small-cell lung cancer (SCLC), adenocarcinoma and squamous-cell cancer (SCC). Therefore, it is of important significance to identify histologic transformation. There are no reports on histologic transformation in brain metastases (BM) to date. The aim of this study was to analyze the histologic transformation in BM for the first time.

METHODS

Medical records were reviewed and patients with both resected BM and primary tumors were examined retrospectively. The histologic diagnosis was confirmed by H&E staining, and additional diagnostic immunohistochemical stains were performed at the discretion of the pathologists. Characteristics of histologic transformation in BM were analyzed.

RESULTS

3 of 24 patients (12.5%) with both resected BM and primary non-small-cell lung cancers (NSCLCs) had evidence of histologic transformation in BM. One case with SCC transformed to adenocarcinoma in brain, one case with adenocarcinoma transformed to SCLC, and another case with adenocarcinoma transformed to SCC. The three cases of histologic transformation were all spontaneous and had not tested gene status.

CONCLUSIONS

We disclosed the histologic transformation of NSCLC in BM at a frequency not as low as expected, and speculated it as an evolution promoted by intratumor heterogeneity, though it warrants further prospective multi-institution investigations with comprehensive molecular analysis. Our findings provided further impetus for surgery when the metastatic or recurrent lesion is resectable, and repeated pathologic evaluation to help tailor individualized treatment.

Successful sequential treatment of refractory tumors caused by small cell carcinoma transformation and EGFR-T790M mutation diagnosed by repeated genetic testing in a patient with lung adenocarcinoma harboring epidermal growth factor receptor mutations: A case report

NSCLC patients with EGFR mutations respond to EGFR-TKIs; however, the management of refractory tumors to EGFR-TKIs remains unclear. We demonstrated that repeated genetic testing might be useful for detecting resistance mechanisms as well as for decision-making in EGFR mutated NSCLC patients, following the emergence of resistance to the initial EGFR-TKIs. A 69-year-old man was diagnosed with lung adenocarcinoma with an EGFR exon 19 deletion. After tumor re-growth treated with erlotinib and chemotherapy, he was diagnosed with an SCLC transformation and administered chemotherapy to treat the SCLC. After the resistance of chemotherapy, the EGFR-T790M mutation by liquid biopsy was detected and treated him with osimertinib, which resulted in a clinical response.

Influence of TP53 Mutation on Survival in Patients With Advanced EGFR-Mutant Non-Small-Cell Lung Cancer

Purpose

TP53 mutation (MT) in epidermal growth factor receptor (EGFR) -MT non-small cell lung cancer (NSCLC) is associated with poor response to targeted therapy; however, its impact on survival is not clearly established.

Patients and Methods

We performed an analysis of patients with stage IV EGFR MT NSCLC with available gene sequencing data. Associations between baseline characteristics; molecular profile, including TP53 MT; and survival outcomes were assessed.

Results

We identified 131 consecutive patients with EGFR MT; 81 (62%) had a TP53 MT, and 55 (42%) had other coexisting oncogenic MTs. Emergent EGFR T790M MT was observed in 42 patients (32%). Overall survival (OS) was longer for younger patients (P = .003), never smokers (P = .002), those with Eastern Cooperative Oncology Group performance status 0 to 1 (P = .004), and emergent T790M MT (P = .018). TP53 MT (P = .021) and other coexisting oncogenic MTs (P = 0.011) were associated with inferior OS. In a multivariable regression analysis adjusted for age, smoking, Eastern Cooperative Oncology Group performance status, and the presence of TP53 MT (P = .063) and other coexisting MTs (P = .064) did not achieve statistical significance. Patients with EGFR T790M/TP53 double MT had worse OS compared with patients with T790M MT alone (46.4 months v 82.9 months). In our series, five patients transformed to small-cell lung cancer (5.6%). All had TP53 MT. In four patients, allelic fraction of TP53 MT increased at the time of transformation.

Conclusion

The presence of TP53 and other coexisting MTs in EGFR MT NSCLC were associated with inferior OS, including patients with emergent T790M MT. An increase in TP53 mutation allelic fraction may potentially be a useful clinical predictor of small-cell transformation.

Small-cell transformation of ALK-rearranged non-small-cell adenocarcinoma of the lung

Anaplastic lymphoma kinase (ALK) gene rearrangements are present in ∼5% of non-small-cell lung cancers (NSCLCs). These rearrangements occur because of a chromosomal inversion within the short arm of Chromosome 2, which results in the formation of the echinoderm microtubule-associated protein-like 4 (EML4)–ALK fusion oncogene. Whereas NSCLC transformation to SCLC is a rare phenomenon described in epidermal growth factor receptor (EGFR) mutant cancers primarily after treatment with targeted therapy, it is exceedingly rare in ALK-rearranged adenocarcinomas. It is currently unclear what the therapeutic significance of the rearrangement is in this transformed tumor as there is a paucity of medical literature describing follow-up care and outcomes of patients in this rare scenario. We describe a unique case in which a patient with ALK-rearranged adenocarcinoma underwent small-cell transformation at a metastatic site with retained ALK rearrangement and was provided clinical follow-up after treatment with second-generation tyrosine kinase inhibiter (TKI) therapy.

Transformation to small-cell lung cancer following treatment with icotinib in a patient with lung adenocarcinoma

The present study describes the case of a 48-year-old man who was diagnosed with lung adenocarcinoma with an epidermal growth factor receptor (EGFR) 21 L858R mutation. The patient received surgery and adjuvant chemotherapy. When multiple lung metastases appeared, icotinib was administered. Following resistance to icotinib, biopsy by endobroncheal ultrasonography for a right lung hilar lymph node revealed transformation to a neuroendocrine morphology. Neuron-specific enolase (NSE) levels were elevated, accompanied with disease progression following transformation to the neuroendocrine morphology. The post-operative and biopsy specimens were analyzed for 416 genes using next-generation sequencing, and phosphatidylinositol-3-kinase catalytic α mutation and retinoblastoma loss were evident. Five cycles of etoposide combined with cisplatin were administered and a partial response was achieved. The disease progressed again accompanied with an elevated NSE level, and bronchoscopy examination revealed small cell lung cancer (SCLC) after 3 months. The patient received chemotherapy consisting of irinotecan combined with carboplatin for two cycles and achieved stable disease. Overall, a secondary biopsy is important for the evaluation of genetic and histological changes and the selection of an appropriate treatment following tyrosine kinase inhibitor (TKI) resistance, and NSE may be useful for the early detection of SCLC transformation in cases that are resistant to EGFR-TKI therapy.

Genetic alterations and protein expression in combined small cell lung cancers and small cell lung cancers arising from lung adenocarcinomas after therapy with tyrosine kinase inhibitors

There are 2 hypotheses regarding the mechanism underlying the adenocarcinoma (AD) to small cell lung cancer (SCLC) transition in patients receiving Tyrosine kinase inhibitor (TKI) therapy: 1) AD gives rise to SCLC owing to the pressure of the TKI therapy, and 2) the SCLC coexists with the AD de novo, but is not detected in biopsy specimens of the heterogeneous tumor. In this study, we try to address this issue by examination the genetic alteration and protein expression profile between SCLC arising from AD, and SCLC in combined small cell lung cancers (CSCLC). In the former, the SCLC had the same genetic profile as the AD, and we strongly suggest that the transition was a consequence of TKI therapy. In the latter, genetic alterations and protein expression tended to differ between the NSCLC and SCLC components of the CSCLC. The results showed that EGFR and KRAS mutation were found in 1 but not both component of CSCLC, and the NSCLC component usually expressed the EGFR and RB1 proteins, whereas the SCLC component did not. This finding indicates that the NSCLC and SCLC components arose separately and that CSCLC are unsuitable for TKI therapy despite the presence of sensitive EGFR mutations.

Therapeutic strategies and genetic profile comparisons in small cell carcinoma and large cell neuroendocrine carcinoma of the lung using next-generation sequencing

Small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC) of the lung are classified as variants of endocrine carcinoma and subdivided into pure or combined type. Clinical benefit of target therapy has not been established in these tumors. This study aimed to compare genetic and clinicopathological features between SCLC and LCNEC or pure and combined types, and explore the possibility of target therapy using next-generation sequencing. In 13 SCLC and 22 LCNEC cases, 72 point mutations, 19 deletions, and 3 insertions were detected. As therapeutically targetable variants, mutations in EGFR (L858R), KRAS (G12D, G12A, G12V), and PIK3CA (E545K) were detected in 5 cases. The case harboring EGFR mutation showed response to EGFR-tyrosine kinase inhibitor. However, there are no clinicopathological features associated with therapeutically targetable cases. And there was no significant genetic feature between SCLC and LCNEC or pure and combined types. In conclusion, although patients with SCLC and LCNEC may benefit from target therapy, they were not identifiable by clinicopathologic background. And there was not significant genetic difference between SCLC and LCNEC, including between pure and combined types. Classifying SCLC and LCNEC in same category is reasonable. However, distinguishing the pure type from combined type was not validated. Comprehensive genetic analysis should be performed to detect targetable variants in any type of SCLC and LCNEC.

[Advances in the Transformation to Small Cell Lung Cancer from Non-small Cell Lung Cancer Following Acquired Drug-resistance to EGFR Tyrosine Kinase Inhibitors]

表皮生长因子受体酪氨酸激酶抑制剂（epidermal growth factor receptor tyrosine kinase inhibitors, EGFR TKIs）在治疗携带EGFR基因敏感突变的非小细胞肺癌（non-small cell lung cancer, NSCLC）中已取得显著疗效，但是，耐药的产生几乎是不可避免的，常见的耐药机制包括T790M突变、cMET基因扩增等。目前已有文献报道EGFR-TKI耐药的机制之一为NSCLC转化为小细胞肺癌（small cell lung cancer, SCLC），大约占3%-15%，是一种重要的少见耐药机制，并不为人们所深入了解。本文从“共同起源”和“转化时间节点”两个角度对其进行了归纳总结，重点探讨了其转化的可能机制，目前提出的两种可能转化机制分别为肿瘤异质性假说、NSCLC转化为SCLC假说，还涉及了许多分子水平的改变，如RB1基因缺失、P53基因失活、PTEN M264I基因突变等，同时对该种转化的发病特点、治疗策略等方面进行了归纳与总结。目前仍有许多问题需要进一步研究和解决。

Molecular Adequacy of Image-Guided Rebiopsies for Molecular Retesting in Advanced Non-Small Cell Lung Cancer: A Single-Center Experience

INTRODUCTION

In the era of biomarker-driven systemic therapy for advanced NSCLC, the role of routine repeated biopsies for decision making outside EGFR-mutant disease remains unproven. We report our center's experience of safety and adequacy for molecular retesting of tumor material obtained from image-guided lung rebiopsies in NSCLC.

METHODS

We performed a retrospective case note analysis of patients undergoing image-guided lung rebiopsies at a single cancer center between 2011 and 2014. The primary objective was to determine the pathological success rate. Secondary and exploratory objectives were to determine technical success rate, histological concordance, molecular adequacy, genotypes identified, and complication rate.

RESULTS

In all, 103 patients underwent transthoracic image-guided procedures. A total of 66 rebiopsies in NSCLC were identified and analyzed. The pathological success rate was 87.1%. A high histological discordance rate was observed (12 of 52 evaluable cases [23.1%]). Pretest molecular adequacy as determined by the lung pathologist was 78.8% (52 of 66). Of 52 adequate samples 51 were sent for molecular analysis, with a total of 209 genes analyzed (including EGFR, ALK receptor tyrosine kinase gene [ALK], KRAS, BRAF, dicoidin domain receptor tyrosine kinase 2 gene [DDR2], NRAS, ROS1, and rearranged during transfection proto-oncogene gene [RET]). The rate of postgenotyping molecular adequacy was 87.1% (182 of 209). Overall, 20 new potentially actionable mutations were identified, with 13 of 66 patients (19.7%) starting to receive new targeted treatment as a result. Overall, rebiopsies informed clinical decision making in 63.6% of cases. The rates of complications were 15% for pneumothorax, 3% for pneumothorax requiring chest drain, and 8% for hemoptysis.

CONCLUSIONS

We have validated the pathological and molecular adequacy rates of rebiopsies and demonstrated clinical utility in routine decision making.

Transformation to small-cell carcinoma as an acquired resistance mechanism to AZD9291: A case report

AZD9291, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), benefits patients with T790M mutant non-small-cell lung cancer who fail treatment with first-generation EGFR TKIs. Acquisition of resistance to AZD9291 occurs inevitable and mechanisms need to be explored. We reported an advanced lung adenocarcinoma female with EGFR exon19 deletion treated on AZD9291 after failure of erlotinib and chemotherapy. Disease progressed again after 6 months treatment of AZD9291 with hepatic metastasis. Re-biopsy of the hepatic lesion showed histopathology transformation to small cell lung cancer, which harbored EGFR exon19 deletion. Therefore, small cell carcinoma transformation is one of potential resistance mechanisms to AZD9291 and regimen for small cell carcinoma may be one of the treatment options.

Outcome of patients with lung adenocarcinoma with transformation to small-cell lung cancer following tyrosine kinase inhibitors treatment: A systematic review and pooled analysis

BACKGROUND

Lung adenocarcinoma can transform to small-cell lung cancer (SCLC) when resistance to tyrosine kinase inhibitors (TKIs) develops. This phenomenon has repeatedly been described in several case reports and small patient series. The characteristics and treatment outcomes of this population, however, have not been comprehensively reported.

METHODS

We performed a systematic review of the published literature to obtain explorative information on the clinical and pathological features and prognosis of the reported cases.

RESULTS

Twenty-five eligible publications were identified, contributing to 39 patients. The median time from initial diagnosis of lung adenocarcinoma to the transformation to SCLC (ttSCLC) was 19months (range 1-61months). The median survival after SCLC diagnosis was 6months. Female gender was significantly associated with longer ttSCLC at the multivariable analysis. Smoking status seemed to be associated with worse prognosis after the diagnosis of SCLC.

CONCLUSION

In this series of published cases, the transformation to a SCLC phenotype after an initial diagnosis of lung adenocarcinoma following TKI therapy appeared to be a late phenomenon. The prognosis after SCLC diagnosis is poor and current treatment strategies derived from primary SCLC seem to be largely inefficacious. New therapies are needed in the management of transformed SCLC.

Overcoming resistance to EGFR tyrosine kinase inhibitors in lung cancer, focusing on non-T790M mechanisms

INTRODUCTION

despite initial dramatic efficacy of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant lung cancer patients, emergence of acquired resistance is almost inevitable. The EGFR T790M secondary mutation that accounts for ~50% of resistance is now treatable with osimertinib. However, for the remaining 50% of patients who develop resistance mechanisms other than T790M mutation, cytotoxic chemotherapies are still the standard of care and novel treatment strategies are urgently needed. Areas covered: In this review, we discuss current experimental and clinical evidence to develop better treatment strategies to overcome or prevent acquired resistance to EGFR-TKIs in lung cancers, focusing on non-T790M mechanisms. Expert commentary: There are numerous non-T790M resistant mechanisms to EGFR-TKIs, and therefore, strategies that can be applied to many of these resistance mechanisms may be reasonable and useful in clinical practice. Although the combination of cytotoxic chemotherapy plus an EGFR-TKI has proved to be detrimental following front-line EGFR-TKI treatment failure, promising experimental and/or early clinical data have been reported for the combination of bevacizumab or anti-EGFR monoclonal antibody plus EGFR-TKIs. Upfront polytherapy, which co-targets potential resistance mechanisms or other important signaling for EGFR-mutant lung cancer cells, is also a promising strategy.

Factors associated with efficacy of first-generation epidermal growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer

The finding of epidermal growth factor receptor tyrosine kinase inhibitors, which reflects a classical process of translational research, is a critical milestone for non-small-cell lung cancer treatment. Currently, epidermal growth factor receptor tyrosine kinase inhibitors are recommended as first-line therapy for non-small-cell lung cancer patients harboring epidermal growth factor receptor-sensitive mutations. The status of epidermal growth factor receptor mutation is widely acknowledged as superior to other clinical factors, such as smoking, gender, and histological types for predicting the response to epidermal growth factor receptor tyrosine kinase inhibitors. However, recent studies have shown that the efficacy might differ in patients with the same epidermal growth factor receptor-sensitive mutations, highlighting the need to investigate the putative factors related to the efficacy of epidermal growth factor receptor tyrosine kinase inhibitors. This article reviews the factors associated with clinical efficacy of first-generation epidermal growth factor receptor tyrosine kinase inhibitors, such as gefitinib and erlotinib, and analyzes their potential implications with respect to clinical application. In addition, new findings related to clinical practice with respect to epidermal growth factor receptor tyrosine kinase inhibitors efficacy were summarized in this article.

Resistance to epithelial growth factor receptor tyrosine kinase inhibitors in a patient with transformation from lung adenocarcinoma to small cell lung cancer: A case report

First-generation epithelial growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have markedly improved the treatment of non-small cell lung cancer (non-SCLC) with EGFR-sensitive mutations. However, acquired resistance to these drugs was inevitable. The transformation of lung adenocarcinoma to SCLC following treatment with EGFR-TKIs is a rare phenomenon that contributes to resistance to EGFR-TKIs. The present case concerns a 74-year-old man previously diagnosed with and treated for pneumonia; however, this was later pathologically confirmed as lung adenocarcinoma by transbronchial lung biopsy. Deletion of exon 19 of EGFR was identified by next-generation sequencing technology. The patient improved markedly when treated with gefitinib, but relapsed after 1 year, with markedly increased serum levels of neuron-specific enolase (NSE). Transformation to SCLC was detected by endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) re-biopsy, which was negative for the deletion of exon 19 of EGFR. The patient was positive for vimentin expression and refractory to etoposide and cisplatin chemotherapy, and succumbed to the disease 18 months after diagnosis. Transformation of the disease from adenocarcinoma to SCLC may have been due to cancer heterogeneity. Re-biopsy is therefore important in EGFR-TKI-resistant patients for genetic and histological re-evaluation. NSE serum levels may also be useful for detecting early SCLC transformation.

NOVEL MARKERS FOR EARLY DIAGNOSIS AND PROGNOSTIC CLASSIFICATION IN MEDULLARY THYROID CARCINOMA

Medullary thyroid carcinoma is a neuroendocrine tumour of the parafollicular C cells of the thyroid gland. It is an aggressive tumor that can be cured only by complete resection of the thyroid tumour and any local and regional metastases. Thus, the discovery of novel diagnostic and prognostic markers is very important for early diagnosis and correct management, in order for the survival rates to rise. New research has emphasized the potential role of various genes, serum and immunohistochemical markers, as well as potential targets for therapeutic agents. The calcium stimulated calcitonin test has been recently reintroduced in clinical practice, and current medullary thyroid carcinoma guidelines encourage laboratories to set their own criteria defining reference ranges for elevated serum basal and stimulated calcitonin levels.

Utility of proGRP as a tumor marker in the medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays the main tumor markers (TM) used in the diagnosis and follow-up of MTC patients are CT and carcinoembryonic antigen (CEA). Nonetheless, progastrin releasing peptide (proGRP) has been recently proposed as a TM useful in the MTC. Our aims were to investigate the release of proGRP in thyroid tumors, its role in the assessment of advanced MTC and its utility in the differential diagnosis between MTC and non-MTC thyroid tumors.

Methods:

Serum samples from 22 patients with MTC and 16 with non-MTC were collected. Patients were classified into advanced cancer or no evidence of disease (NED). ProGRP was performed by Architect (Abbot Diagnostics), CT by Liaison (Diasorin) and CEA by Cobas E601(Roche Diagnostics).

Results:

ProGRP median concentration in advanced MTC was significantly higher (1398.4 pg/mL) when compared with non-MTC, either in advanced disease (24.9 pg/mL) or NED (14.6 pg/mL). In non-MTC patients, proGRP median concentration was below its cutoff level (50 pg/mL). Similar to CT, proGRP was able to detect 88.9% of MTC patients, but with a slightly lower specificity of 76.9%. Using proGRP together with CT the sensitivity increased to 100%.

Conclusions:

The low prevalence of this malignancy strongly recommends further collaborative studies, mainly focused on monitoring proGRP during tyrosine kinase inhibitors treatment for early detection of resistance and assessing its usefulness to avoid the observed false positive fluctuations that occur with CT and CEA.

Effect of dasatinib on EMT-mediated-mechanism of resistance against EGFR inhibitors in lung cancer cells

OBJECTIVE

The epithelial to mesenchymal transition (EMT) is associated with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in certain non-small cell lung cancers that harbor EGFR mutations. Because no currently available drugs specifically kill cancer cells via EMT, novel treatment strategies that overcome or prevent EMT are needed. A recent report suggested that dasatinib (an ABL/Src kinase inhibitor) inhibits EMT induced by transforming growth factor (TGF)-beta in lung cancer cells (Wilson et al., 2014). In this study, we analyzed effects of dasatinib on the resistance mechanism in HCC4006 cells, which tend to acquire resistance to EGFR-TKIs via EMT.

MATERIALS AND METHODS

Sensitivity to dasatinib in HCC4006 and HCC4006 erlotinib-resistant (ER) cells with an EMT phenotype was analyzed. HCC4006 cells acquired resistance against the combination of erlotinib and dasatinib (HCC4006EDR) following chronic treatment with these drugs. The expression of EMT markers and the resistance mechanism were analyzed.

RESULTS

Short-term or long-term treatment with dasatinib did not reverse EMT in HCC4006ER. In contrast, HCC4006EDR cells maintained an epithelial phenotype, and the mechanism underlying resistance to erlotinib plus dasatinib combination therapy was attributable to a T790M secondary mutation. HCC4006EDR cells, but not HCC4006ER cells, were highly sensitive to a third-generation EGFR-TKI, osimertinib.

CONCLUSIONS

Although dasatinib monotherapy did not reverse EMT in HCC4006ER cells, preemptive combination treatment with erlotinib and dasatinib prevented the emergence of acquired resistance via EMT, and led to the emergence of T790M. Our results indicate that preemptive combination therapy may be a promising strategy to prevent the emergence of EMT-mediated resistance.

Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms

The wide application of immunohistochemistry to the study of tumors has led to the recognition that epithelial neoplasms composed of both a neuroendocrine and nonneuroendocrine component are not as rare as traditionally believed. It has been recommended that mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are classified as only those in which either component represents at least 30 % of the lesion but this cutoff has not been universally accepted. Moreover, since their pathogenetic and clinical features are still unclear, mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are not included as a separate clinicopathological entity in most WHO classifications, although they have been observed in virtually all organs. In the WHO classification of digestive tumors, mixed neuroendocrine-nonneuroendocrine neoplasm is considered a specific type and is defined as mixed adenoneuroendocrine carcinoma, a definition that has not been accepted for other organs. In fact, this term does not adequately convey the morphological and biological heterogeneity of digestive mixed neoplasms and has created some misunderstanding among both pathologists and clinicians. In the present study, we have reviewed the literature on mixed neuroendocrine-nonneuroendocrine epithelial neoplasms reported in the pituitary, thyroid, nasal cavity, larynx, lung, digestive system, urinary system, male and female genital organs, and skin to give the reader an overview of the most important clinicopathological features and morphological criteria for diagnosing each entity. We also propose to use the term "mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN)" to define and to unify the concept of this heterogeneous group of neoplasms, which show different characteristics mainly depending on the type of neuroendocrine and nonneuroendocrine components.

Case report: small cell transformation and metastasis to the breast in a patient with lung adenocarcinoma following maintenance treatment with epidermal growth factor receptor tyrosine kinase inhibitors

BACKGROUND

Breast metastasis from lung cancer has been reported, but not from SCLC that is transformed from lung adenocarcinoma during maintenance treatment with epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). Transformation to small cell lung cancer(SCLC), although uncommonly seen, has been associated with resistance to EGFR-TKI therapy in lung adenocarcinomas.

CASE PRESENTATION

We describe a case of a 49-year-old man with lung adenocarcinoma harboring L858R point mutation at the exon 21 of the epidermal growth factor receptor (EGFR). During the maintenance treatment with EGFR-TKI, the patient presented with a right breast mass, which was accompanied by elevated serum neuron specific enolase (NSE) level. The histological examination of biopsies from the breast mass and enlarging lung mass revealed SCLC that was less sensitive to standard SCLC treatment. The breast tumor was positive for thyroid transcription factor-1 (TTF-1), consistent with a lung primary cancer.

CONCLUSION

This is the first case report of small cell transformation and metastatic to the breast in a patient with lung adenocarcinoma following EGFR-TKI treatment. Repeat biopsy is important for evaluation of evolving genetic and histologic changes and selection of appropriate treatment. and serum NSE measurement may be useful for detection of small cell transformation in cases with resistance to EGFR-TKI therapy.

Histopathological transformation to small-cell lung carcinoma in non-small cell lung carcinoma tumors

Lung cancer is the principal cause of cancer-related death worldwide. The use of targeted therapies, especially tyrosine kinase inhibitors (TKIs), in specific groups of patients has dramatically improved the prognosis of this disease, although inevitably some patients will develop resistance to these drugs during active treatment. The most common cancer-associated acquired mutation is the epidermal growth factor receptor (EGFR) Thr790Met (T790M) mutation. During active treatment with targeted therapies, histopathological transformation to small-cell lung carcinoma (SCLC) can occur in 3-15% of patients with non-small-cell lung carcinoma (NSCLC) tumors. By definition, SCLC is a high-grade tumor with specific histological and genetic characteristics. In the majority of cases, a good-quality hematoxylin and eosin (H&E) stain is enough to establish a diagnosis. Immunohistochemistry (IHC) is used to confirm the diagnosis and exclude other neoplasia such as sarcomatoid carcinomas, large-cell carcinoma, basaloid squamous-cell carcinoma, chronic inflammation, malignant melanoma, metastatic carcinoma, sarcoma, and lymphoma. A loss of the tumor-suppressor protein retinoblastoma 1 (RB1) is found in 100% of human SCLC tumors; therefore, it has an essential role in tumorigenesis and tumor development. Other genetic pathways probably involved in the histopathological transformation include neurogenic locus notch homolog (NOTCH) and achaete-scute homolog 1 (ASCL1). Histological transformation to SCLC can be suspected in NSCLC patients who clinically deteriorate during active treatment. Biopsy of any new lesion in this clinical setting is highly recommended to rule out a SCLC transformation. New studies are trying to assess this histological transformation by noninvasive measures such as measuring the concentration of serum neuron-specific enolase.

Management of Small Cell Lung Cancer: Progress and Updates

Small cell lung cancer (SCLC) remains a major public health problem and accounts for 10% to 15% of all lung cancers. It has unique clinical features such as rapid growth, early metastatic spread, and widespread dissemination. A platinum-etoposide combination is the backbone treatment of SCLC; addition of thoracic and prophylactic cranial irradiation has been shown to improve outcome in limited-stage SCLC and in subgroups of extensive-stage SCLC. Over the last decade, significant progress has been made in characterizing the SCLC tumor biology and its developmental pathways. Most recently, efforts have focused not only on molecular targets, but also on the development of novel drugs targeting tumor evolution and immune escape mechanisms; these approaches are promising and offer opportunities that may finally improve the outcomes of SCLC.

A Prospective Evaluation of Circulating Tumor Cells and Cell-Free DNA in EGFR-Mutant Non-Small Cell Lung Cancer Patients Treated with Erlotinib on a Phase II Trial

PURPOSE

Genotype-directed therapy is the standard of care for advanced non-small cell lung cancer (NSCLC), but obtaining tumor tissue for genotyping remains a challenge. Circulating tumor cell (CTC) or cell-free DNA (cfDNA) analysis may allow for noninvasive evaluation. This prospective trial evaluated CTCs and cfDNA in EGFR-mutant NSCLC patients treated with erlotinib until progression.

EXPERIMENTAL DESIGN

EGFR-mutant NSCLC patients were enrolled in a phase II trial of erlotinib. Blood was collected at baseline, every 2 months on study, and at disease progression. Plasma genotyping was performed by droplet digital PCR for EGFR19del, L858R, and T790M. CTCs were isolated by CellSave, enumerated, and analyzed by immunofluorescence for CD45 and pan-cytokeratin and EGFR and MET FISH were also performed. Rebiopsy was performed at disease progression.

RESULTS

Sixty patients were enrolled; 44 patients discontinued therapy for disease progression. Rebiopsy occurred in 35 of 44 patients (80%), with paired CTC/cfDNA analysis in 41 of 44 samples at baseline and 36 of 44 samples at progression. T790M was identified in 23 of 35 (66%) tissue biopsies and 9 of 39 (23%) cfDNA samples. CTC analysis at progression identified MET amplification in 3 samples in which tissue analysis could not be performed. cfDNA analysis identified T790M in 2 samples in which rebiopsy was not possible. At diagnosis, high levels of cfDNA but not high levels of CTCs correlated with progression-free survival.

CONCLUSIONS

cfDNA and CTCs are complementary, noninvasive assays for evaluation of acquired resistance to first-line EGFR TKIs and may expand the number of patients in whom actionable genetic information can be obtained at acquired resistance. Serial cfDNA monitoring may offer greater clinical utility than serial monitoring of CTCs. Clin Cancer Res; 22(24); 6010-20. ©2016 AACR.

MLH1 V384D polymorphism associates with poor response to EGFR tyrosine kinase inhibitors in patients with EGFR L858R-positive lung adenocarcinoma

A significant fraction of patients with lung adenocarcinomas harboring activating epidermal growth factor receptor (EGFR) mutations do not experience clinical benefits from EGFR tyrosine kinase inhibitor (TKI) therapy. Using next-generation sequencing, we screened 739 mutation hotspots in 46 cancer-related genes in EGFR L858R-mutant lung adenocarcinomas from 29 patients who received EGFR-TKI therapy; 13 had short (< 3 months) and 16 had long (> 1 year) progression-free survival (PFS). We discovered MLH1 V384D as a genetic variant enriched in the group of patients with short PFS. Next, we investigated this genetic variation in 158 lung adenocarcinomas with the EGFR L858R mutation and found 14 (8.9%) patients had MLH1 V384D; available blood or non-tumor tissues from patients were also tested positive for MLH1 V384D. Patients with MLH1 V384D had a significantly shorter median PFS than those without (5.1 vs. 10.6 months; P= 0.001). Multivariate analysis showed that MLH1 V384D polymorphism was an independent predictor for a reduced PFS time (hazard ratio, 3.5; 95% confidence interval, 1.7 to 7.2; P= 0.001). In conclusion, MLH1 V384D polymorphism is associated with primary resistance to EGFR-TKIs in patients with EGFR L858R-positive lung adenocarcinoma and may potentially be a novel biomarker to guide treatment decisions.