Epidermal growth factor receptor (EGFR) mutations in small cell lung cancers: Two cases and a review of the literature

Primary de novo Epidermal Growth Factor Receptor Mutant Small Cell Lung Carcinomas: Clinicopathological Study of a Rare Entity Presenting in Treatment-Naïve Setting with Review of Literature

Introduction: Small cell lung carcinomas (SCLC) are characterized by loss of function mutations in genes encoding for p53 (tumor protein p53-TP53) and retinoblastoma transcriptional corepressor 1 (RB1) proteins in the majority of tumors. They are aggressive, usually present with metastatic disease, and are treated with platinum-based chemotherapy with overall poor outcomes. Epidermal growth factor receptor (EGFR) mutations, classically associated with primary lung adenocarcinomas, have been reported in rare de novo SCLC outside the context of the relatively more common transformed SCLC that arise with emergence of tyrosine kinase inhibitor resistance in EGFR-mutant adenocarcinomas. Aim: To analyze the clinicopathological features of EGFR-mutant de novo SCLC. Methods: EGFR-mutant de novo SCLCs were retrieved over 5 years and reviewed for clinicopathological parameters. Results: Five patients were identified harboring either exon 19 deletion (n = 4) or exon 21 L858R mutation (n = 1) in EGFR. Median age at diagnosis was 48 years (30-58 years). Four patients were never-smokers of whom three were tobacco chewers. Three biopsies showed pure small cell carcinoma while others showed composite adenocarcinoma. Diffuse loss of RB1 (5/5) and mutant type p53 staining pattern (3/3) were noted in all tested samples. Among two patient samples subjected to sequencing, additional pathogenic mutations in TP53 (2/2), RB1 (1/2), PTEN (1/2), neurofibromatosis type 1 (1/2), and CREBB1 (1/2) were identified. Conclusion: EGFR-mutant de novo SCLCs are extremely rare and show frequent inactivation of p53 and RB1, like the more common transformed SCLCs. Given the lack of tyrosine kinase inhibitor exposure, these tumors highlight the inherent lineage plasticity of EGFR/TP53/RB1 triple mutant lung carcinomas.

Exploring the prognostic impact of differences in treatment strategies for SCLC with different histologies and prognostic factors for C-SCLC: A SEER population-based study

Background

Combined small cell lung cancer (C-SCLC) is a rare type of small cell lung cancer (SCLC), and it is controversial whether to choose the same treatment regimen as SCLC due to its multiple histologic components.

Study methods and results

Records of patients with small cell lung cancer diagnosed between 2010 and 2020 were extracted using the SEER database. The OS of patients with different histological types under the same staging and treatment regimen was analyzed. It was found that early-stage (stage IA-IIA) surgical treatment, systemic chemotherapy alone, and chemoradiotherapy were more efficacious than C-SCLC and P-SCLC in patients with limited-stage (P = 0.054, P = 0.001, P = 0.019). In patients with extensive staging, the OS of patients with systemic chemotherapy regimens differed (P = 0.045) and was better in C-SCLC than in P-SCLC. We further explored the treatment strategy for patients with C-SCLC, which was shown by a COX regression model based on prognostic factors screened by Random Forest and LASSO regression models. Surgery, radiotherapy, and chemotherapy would be beneficial for survival. In a subgroup analysis based on stage and treatment regimen, it was shown that patients with early staging (stage IA-IIA) had a better prognosis with surgery (P < 0.001); in patients with extensive staging, chemoradiotherapy was favorable to the patient's prognosis (P = 0.022).

Conclusion

Both limited-stage and extensive-stage C-SCLC patients are more sensitive to chemotherapy than P-SCLC patients. Patients with C-SCLC who have access to surgery should undergo surgery as early as possible, while chemoradiotherapy is recommended for patients with extensive staging. Patient age, gender, tumor size, surgery, chemotherapy, radiotherapy, and metastasis may individually affect patient prognosis.

Dissecting the genetic variations associated with response to first-line chemotherapy in patients with small cell lung cancer: a retrospective cohort study

Background

Chemotherapy has been the standard treatment for small-cell lung cancer (SCLC) for decades. Nonetheless, patients are usually responsive to initial chemotherapy but quickly suffer from relapse, resulting in a poor long-term outcome. Treating advances that greatly ameliorate survival outcomes are historically finite, and credible biomarkers for therapeutic evaluation are deficient. As the genetic biology emerges, investigating biomarkers to optimize individualized treatment for SCLC is necessary.

Methods

Based on following inclusion criteria: (I) patients diagnosed as SCLC by pathology; (II) patients treated with first-line etoposide/cisplatin (EP) chemotherapy; (III) patients who received long-term follow-up and signed informed consent, a total of 24 SCLC patients receiving first-line standard chemotherapy were divided into progressive disease (PD) and partial response (PR) groups. They were regularly followed every 3 months with computed tomography (CT) scan until recurrences determined by CT scan results. Next-generation sequencing (NGS) with a panel of 1,406 cancer-related genes was conducted on the tumor tissue-derived DNA of patients to compare genetic variations, including deletions (indels), single nucleotide variations (SNVs), copy number variations (CNVs), and copy number instability (CNI) between the two groups.

Results

For the clinical characteristics of enrolled SCLC patients, except for significant differences in sex, age, clinical stage, and limited or extensive stage, PD patients showed distinctly shorter overall survival than those with PR (6.5 vs. 14.0 months, respectively, P=0.007). Genetic variations analysis discovered several common genes with CNV mutations between the PR and PD groups, and increased epidermal growth factor receptor (EGFR) gene copy numbers gain was found in PR groups in comparing with PD patients (P=0.006). However, no significant differences in terms of SNVs, indels, genotypes associated with first-line chemotherapy, CNI of tumor tissue-derived DNA, and tumor mutational burden of tumor tissues were observed between two groups. Additionally, the relationship between EGFR gene mutation and clinicopathological features of SCLC indicated that EGFR gene mutation may be an independent indicator for SCLC patients.

Conclusions

Increased EGFR gene CNVs may be an independent indicator influencing the survival time and PR in SCLC patients receiving standard first-line chemotherapy.

Clinicopathological and Treatment Patterns of Combined Small-Cell Lung Carcinoma with Future Insight to Treatment: A Population-Based Study

BACKGROUND

Primary lung cancer is the most common cause of cancer-related mortality in the United States (US). Approximately 90% of lung cancers are associated with smoking and the use of other tobacco products. Based on histology, lung cancers are divided into small-cell lung carcinomas (SCLCs) and non-small-cell lung carcinomas (NSCLCs). Most SCLCs are of the pure subtype, while the rare combined SCLCs contain elements of both small-cell and non-small-cell morphologies. This study sought to evaluate the demographics, clinical factors, molecular abnormalities, treatment approaches, and survival outcomes with combined SCLC and NSCLCs.

MATERIALS AND METHODS

Data on 2126 combined SCLC patients was extracted from the Surveillance Epidemiology and End Result (SEER) database from 2000 to 2018. Data extracted for analyses included age, sex, race, tumor size, tumor location, metastasis status, stage at diagnosis, treatment received, and treatment outcomes. Multivariate analysis was performed using Statistical Product and Service Solutions (SPSS) software.

RESULTS

The patients had a median age of 68 years; 43.9% of the patients were female and 56.1% were male; 84.5% were White and 11.7% were African Americans. The majority of patients had a poorly differentiated disease at 29.6%; 17% were undifferentiated, 3.2% were moderately differentiated, and 0.8% were well differentiated. Chemotherapy was the most common treatment modality (45.3%); 17% underwent surgery only, 10.3% underwent surgery followed by adjuvant chemotherapy, and 10% underwent radiation after surgery. Five-year cancer-specific survival was 15.2% with surgery alone, and combined surgery and chemotherapy provided the highest percentages (38.3% and 34.7%, respectively). Females had significantly higher 1- and 5-year cancer-specific survival rates compared to males (59.3% and 29.9% vs. 48.0% and 23.7, respectively; p < 0.001). Well-differentiated tumors had significantly higher survival compared to other gradings (p < 0.001). Survival decreased as tumor staging moved distally from localized to regional to distant (p < 0.001). Metastasis to bone, liver, brain, and lung significantly decreased survival in comparison to patients who did not have any metastasis (p < 0.001). Females had significantly shorter survival compared to their counterparts when metastasis was to the bone, brain, or liver (p < 0.001). Multivariate analysis identified male sex (Hazard Ratio (HR) = 1.2), undifferentiated grade (HR = 1.9), regional extent of disease (HR = 1.7), distant extent of disease (HR = 3.7), and metastasis to liver (HR = 3.5) as variables associated with worse survival.

CONCLUSION

Combined SCLC is overall very rare. However, the frequency of presentation with combined SCLC is on the rise, in part due to improvements in diagnostic techniques. Despite advances in therapies, treating combined SCLC is challenging, and novel therapies are not utilized, owing to low rates of targetable mutations. Combined SCLC has higher survival rates if well differentiated.

Detection of clinically-relevant <em>EGFR</em> variations in <em>de novo</em> small cell lung carcinoma by droplet digital PCR

Targeted therapy that utilizes tyrosine kinase inhibitors (TKIs), specific to epidermal growth factor receptors (EGFR) has changed the landscape of treatment of non-small cell lung cancer (NSCLC). The success or failure of this approach depends on presence of certain variations in the tyrosine kinase domain of EGFR gene. Generally, patients diagnosed with Small cell lung cancer (SCLC) are considered ineligible for TKI therapy owing to the absence of EGFR variations. . However, there is evidence of these variations being detected in SCLCs, both in de-novo and in transformed SCLCs (TKI-treated adenocarcinomas). Despite the presence of clinically-relevant EGFR variations in SCLCs, the response to TKIs has been inconsistent.  Liquid biopsy is a well-established approach in lung cancer management with proven diagnostic, prognostic and predictive applications. It relies on detection of circulating tumor-derived nucleic acids present in plasma of the patient. In this study, a liquid biopsy approach was utilized to screen 118 consecutive lung cancer patients for four clinically-relevant variations in EGFR gene, which included three activating/sensitizing variations (Ex18 G719S, Ex19del E746-A750 and Ex21 L858R) and one acquired/resistance (Ex20 T790M, de novo) variation by droplet digital PCR, the most advanced third generation PCR technique. As expected, clinically-relevant EGFR variations were found in majority of the non-small cell lung cancer cases. However, among the handful of small cell lung cancer samples screened, sensitizing variations (Ex18 G719S and Ex21 L858R) were seen in almost all of them. Interestingly, Ex20 T790M variation was not detected in any of the cases screened.  The results of our study indicate that EGFR variations are present in SCLCs and highly sensitive liquid biopsy techniques like ddPCR can be effectively utilized for this purpose of screening EGFR variations in such samples.

[MDT Treatment of Small Cell Lung Cancer Complicated with Adenocarcinoma: A Case Report and Literature Review]

Small cell lung cancer (SCLC) is the most malignant lung cancer with the highest mortality. At present, the first-line standard treatment is still based on Etoposide and Platinum chemotherapy. However, for SCLC that progresses after first-line therapy, the treatment options are still very limited. Since the molecular mechanism of first-line drug resistance of SCLC is still unclear, and the precision medicine strategy after first-line drug resistance is still in the pre-clinical stage. The proportion of secondary biopsy and genetic testing is very low after the progress of first-line treatment of SCLC. In this study, we report a case of a middle-aged woman who was first diagnosed with SCLC. Adenocarcinoma with sensitive gene mutations and repeated changes of small cell carcinoma were detected by multiple biopsies during the course of the disease, suggesting that the patient may be a special subtype of SCLC - mixed SCLC (M-SCLC). In this case, the patient has been treated with radiotherapy and chemotherapy, immunotherapy and targeted therapy successively, and the survival time has reached 2 years and 8 months. Through the case report and literature review retrospectively, this study aimed to explore the part patients may start to present hybrid histopathologic types or tissue type change after treatment of SCLC. Biopsy pathologic histology and genetic testing is necessary after disease progression to look for potential therapeutic targets, so as to give precise treatment based on molecular markers detection results and provide the patient with the benefit of survival for as long as possible.
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Multi-channel multi-task deep learning for predicting EGFR and KRAS mutations of non-small cell lung cancer on CT images

BACKGROUND

Predicting the mutation statuses of 2 essential pathogenic genes [epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma (KRAS)] in non-small cell lung cancer (NSCLC) based on CT is valuable for targeted therapy because it is a non-invasive and less costly method. Although deep learning technology has realized substantial computer vision achievements, CT imaging being used to predict gene mutations remains challenging due to small dataset limitations.

METHODS

We propose a multi-channel and multi-task deep learning (MMDL) model for the simultaneous prediction of EGFR and KRAS mutation statuses based on CT images. First, we decomposed each 3D lung nodule into 9 views. Then, we used the pre-trained inception-attention-resnet model for each view to learn the features of the nodules. By combining 9 inception-attention-resnet models to predict the types of gene mutations in lung nodules, the models were adaptively weighted, and the proposed MMDL model could be trained end-to-end. The MMDL model utilized multiple channels to characterize the nodule more comprehensively and integrate patient personal information into our learning process.

RESULTS

We trained the proposed MMDL model using a dataset of 363 patients collected by our partner hospital and conducted a multi-center validation on 162 patients in The Cancer Imaging Archive (TCIA) public dataset. The accuracies for the prediction of EGFR and KRAS mutations were, respectively, 79.43% and 72.25% in the training dataset and 75.06% and 69.64% in the validation dataset.

CONCLUSIONS

The experimental results demonstrated that the proposed MMDL model outperformed the latest methods in predicting EGFR and KRAS mutations in NSCLC.

Combined small cell lung carcinoma harboring ALK rearrangement: A case report and literature review

Combined small cell lung cancer (c‐SCLC) is a relatively rare subtype of SCLC and is defined by the combination of SCLC and any elements of non‐small cell carcinoma (NSCLC). Standard chemotherapy for patients with c‐SCLC has not yet been established. Gene mutations such as epidermal growth factor receptor (EGFR) mutations may be detected in patients with c‐SCLC. However, little is known about anaplastic lymphoma kinase (ALK) rearrangement in c‐SCLC patients. Here, we report a young female patient who was successfully treated with alectinib for ALK‐positive c‐SCLC after failure of immunochemotherapy for SCLC and cytotoxic chemotherapy for adenocarcinoma. Moreover, we performed a literature review of EGFR‐ or ALK‐positive c‐SCLC patients. Our report suggests that ALK testing may be justified in patients with SCLC that contain an adenocarcinoma component.

Key points

Significant findings of the study

• This is the first report describing the treatment course comprising immunochemotherapy and ALK‐TKI in a patient with c‐SCLC harboring ALK rearrangement.

What this study adds

• Our case and literature review suggest that although ALK mutation is rare in patients with c‐SCLC, its identification and treatment with ALK‐TKIs may contribute to clinical benefits.

Resistance to Both Chemotherapy and EGFR-TKI in Small Cell Lung Cancer With EGFR 19-Del Mutation: A Case Report

Epidermal growth factor receptor (EGFR) mutations are common in non-small cell lung cancers, but rare in small cell lung cancers (SCLCs). In previous reports, some SCLC patients with EGFR mutations could benefit from EGFR tyrosine kinase inhibitors (TKIs). In this study, we reported a case in which an SCLC patient with EGFR exon 19 deletion (19-Del) mutation did not benefit from EGFR-TKIs. Interestingly, the standard treatment strategies for SCLC also failed to control tumor progression. Moreover, we screened 43 SCLC patients in China and found that the frequency of EGFR mutations in Chinese SCLC patients was about 4.65% by next-generation sequencing (NGS). Collectively, this case illustrated a rare subtype of SCLCs which harbored EGFR mutations and was intrinsically resistant to standard treatments and EGFR-TKIs. We also tried to explore the mechanisms underlying drug resistance. The literature concerning SCLCs with EGFR mutations is reviewed.

Transformation from EGFR/PTEN co-mutated lung adenocarcinoma to small cell carcinoma in lymph node metastasis

There is minimal evidence of EGFR-mutated lung adenocarcinoma transforming to small cell lung carcinoma (SCLC) without the administration of EGFR-tyrosine kinase inhibitor (TKI). Here, we present a case of EGFR/PTEN co-mutated lung adenocarcinoma with lymph node metastases, which comprised adenocarcinoma admixed with SCLC. EGFR L858R and PTEN R130Q mutations were shared between the primary tumor and lymph node metastasis. Additionally, EGFR I744M mutation was shared between the adenocarcinoma and SCLC components in the lymph node metastasis, confirming spontaneous transformation from adenocarcinoma to SCLC. Furthermore, TP53 and RB1 mutations were detected only in the SCLC components of the lymph node metastasis. Immunohistochemically, complete absence of Rb expression in SCLC was observed, suggesting the loss of function of RB1. Our case clearly shows that EGFR/PTEN co-mutated lung adenocarcinoma transformed to SCLC in the lymph node without TKI-mediated evolutionary selection pressures.

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.

Combined small-cell lung carcinoma

Currently, studies assessing combined small-cell lung carcinoma (C-SCLC) are relatively scarce and limited. Indeed the clinicopathological features, treatment, and prognosis of patients with C-SCLC have not been fully determined. The incidence of C-SCLC ranges from 5%–28% in different studies, which is related to the specimen types used. The clinical features of C-SCLC are characterized by the higher proportion of peripheral locations, earlier stage, and more opportunity to experience surgery. Surgery is more important for earlier stage C-SCLC. There have been no recent changes in the chemotherapy of C-SCLC, which is recommended by the treatment guidelines for SCLC, neither showing survival benefit from the 3-agent regimen. Meanwhile, the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutated C-SCLC patients remains inconclusive. This review focuses on clinical and pathologic features, prognostic factors, and optimized treatment model in C-SCLC.

Successful treatment with an EGFR tyrosine kinase inhibitor Afatinib in a patient with combined small-cell lung Cancer with EGFR mutation

Small-cell lung cancer (SCLC) combined with epidermal growth factor receptor (EGFR) mutations is extremely rare, and standard chemotherapeutic strategies have not yet been established. In the present study, we report a case of a 67-year-old man who presented with combined SCLC with EGFR mutation (exon 19 deletion). Systemic chemotherapy with cisplatin and irinotecan was initiated as first-line chemotherapy, and computed tomography findings revealed tumor shrinkage after two cycles of chemotherapy. However, after the third cycle of the treatment, disease progression was observed including the appearance of pleural and pericardial effusion. Cytologic examination of pleural and pericardial effusion revealed adenocarcinoma and no characteristics of SCLC, and an EGFR mutation was detected, in line with the initial diagnosis. Afatinib was then administered as second-line chemotherapy, which resulted in a partial response that lasted for 6 months. Re-biopsy after resistance to first-line chemotherapy suggested that the adenocarcinoma component harboring the EGFR mutation became dominant in association with disease progression, and afatinib provided clinical efficacy as second-line chemotherapy.

Molecular diagnostics of lung cancer in the clinic

According to current practice guidelines, all patients with advanced non-small cell lung cancer (NSCLC) should undergo predictive biomarker testing. For squamous cell carcinoma patients, PD-L1 immunohistochemistry is indicated to select patients for immunotherapy in the first line. For lung adenocarcinoma, all patients with advanced disease should undergo testing for epidermal growth factor receptor (EGFR) mutations, ALK and ROS1 rearrangements, and PD-L1 expression to predict response to EGFR, ALK, or ROS1 targeted inhibitors or immunotherapy, respectively. Besides these, a number of other biomarkers are under clinical investigation as predictors of response to targeted therapies, including BRAF, ERBB2, MET splice mutations and amplification, and RET rearrangements. Successful testing for this complex array of molecular targets demands careful coordination between proceduralists, pathologists and molecular laboratories to ensure proper tumor tissue handling following biopsy as well as judicious use of diagnostic immunohistochemistry. Even so, sample failure rates due to inadequate tumor tissue are high in practice, particularly when using sequential testing methods. Use of next generation sequencing (NGS) in clinical practice can enable detection of multiple targets and multiple alteration types (mutation, gene copy change, and rearrangement) simultaneously even with small amounts of input nucleic acids, thus increasing molecular testing success rates. In patients with an established lung cancer diagnosis but with prohibitively limited amounts of tumor tissue or who are experiencing relapse, analyses of circulating tumor DNA (ctDNA) from the plasma can serve as an alternate testing substrate, however the more limited clinical sensitivity of this approach must be taken into account. This review will explore the indications for and pitfalls of routine NGS and plasma genotyping in the clinic, including the intersection of these technologies.