Transformation of NSCLC to SCLC after 1st- and 3rd-generation EGFR-TKI resistance and response to EP regimen and erlotinib: 2 CARE-compliant case reports

ALK-rearranged and EGFR wild-type lung adenocarcinoma transformed to small cell lung cancer: a case report

Background

Cases of ALK-rearranged EGFR wild-type lung adenocarcinoma (LUAD) transforming into small cell lung cancer (SCLC) are rarely reported, and diagnosis is often delayed. The emergence of this transformation phenomenon is often regarded as a consequence of acquired resistance mechanisms.

Case presentation

A 47-year-old male diagnosed with poorly differentiated adenocarcinoma of the right middle lung (pT2N2M0, stage IIIA) achieved a 46-month progression-free survival (PFS) following surgery and adjuvant chemotherapy. During routine follow-up, tumor recurrence and metastasis was detected. Genetic testing revealed ALK rearrangement and wild-type EGFR, prompting treatment with ALK-TKIs. In May 2023, abdominal CT scans showed significant progression of liver metastases and abnormal elevation of the tumor marker NSE. Immunohistochemical results from percutaneous liver biopsy indicated metastatic SCLC.

Results

After resistance to ALK-TKIs and transformation to SCLC, the patient received chemotherapy combined with immunotherapy for SCLC, but the patient's disease progressed rapidly. Currently, the patient is being treated with albumin-bound paclitaxel in combination with oral erlotinib and remains stable.

Conclusion

Histological transformation emerges as a compelling mechanism of resistance to ALK-TKIs, necessitating the utmost urgency for repeat biopsies in patients displaying disease progression after resistance. These biopsies are pivotal in enabling the tailor-made adaptation of treatment regimens to effectively counteract the assorted mechanisms of acquired resistance, thus optimizing patient outcomes in the battle against ALK-driven malignancies.

Allelic Context of EGFR C797X-Mutant Lung Cancer Defines Four Subtypes With Heterogeneous Genomic Landscape and Distinct Clinical Outcomes

INTRODUCTION

EGFR C797X (C797S or C797G) mutation is the most frequent on-target mechanism of resistance to osimertinib. The hypothesis that the allelic context of C797X/T790M has implications for treatment is on the basis of sporadic reports and needs validation with larger cohorts.

METHODS

We identified patients with EGFR C797X-mutant NSCLC from nine centers who progressed on osimertinib, all analyzed in a single laboratory through next-generation sequencing. We analyzed genomic profiles and assessed associations between clinical outcomes and C797X status.

RESULTS

A total of 365 EGFR C797X-mutant cases were categorized into four subtypes on the basis of allelic context: in cis (75.3%), in trans (6.4%), cis&trans (10.4%), and C797X-only (7.9%). Genomically, the cis&trans subtype displayed the highest frequency of concurrent alterations at osimertinib resistance sites (21.1%), while the in cis subtype had the lowest (8.4%). Clinically, cis&trans patients exhibited the worst progression-free survival (PFS) on both previous (median 7.7 mo) and subsequent treatment (median 1.0 mo) and overall survival (median 3.9 mo). In subsequent treatments, in cis patients exhibited superior PFS with combined brigatinib and cetuximab (median 11.0 mo) compared with other regimens (p = 0.005), while in trans patients exhibited variable outcomes with combined first or second- and third-generation EGFR inhibitor (PFS range: 0.7-8.1 mo, median 2.6 mo). Notably, subtype switching was observed after subsequent treatments, predominantly toward the in cis subtype.

CONCLUSIONS

Allelic context could define four EGFR C797X-mutant NSCLC subtypes with heterogeneous genetic landscapes and distinct clinical outcomes. Subsequent treatments further complicate the scenario through subtype switching.

Small cell conversion complicated with hypertrophic pulmonary osteoarthropathy after targeted therapy for advanced EGFR-mutated lung adenocarcinoma: A case report

In recent years, with the opening of the era of precision therapy, the treatment of patients with positive driver genes is a hot issue in global research. EGFR is the most common driver gene in NSCLC, with a positivity rate of 17%. Although targeted drugs for EGFR mutations can benefit this population with efficacy, target therapy resistance inevitably occurs. The presented case suggests that a patient with advanced lung adenocarcinoma with EGFR mutation who developed pathological-type conversion of small cell lung cancer complicated with the development of hypertropic pulmonary osteoarthropathy (HPOA) after 6 months of targeted therapy. This case demonstrates that early diagnosis of HPOA can predict the occurrence of target resistance and pathologic conversion in patients with positive driver genes, providing new clues for the clinical management of lung cancer.

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.

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.

Characterization of non-small cell lung cancer transforming to small cell lung cancer and its response to EGFR-TKI: a case report

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated significant survival benefits for advanced non-small cell lung cancer (NSCLC) patients with sensitive EGFR mutations. However, patients with EGFR-TKI treatment often develop acquired resistance subsequently. Transformation from NSCLC to small cell lung cancer (SCLC) is a rare EGFR-TKI resistance mechanism for patients with sensitive EGFR mutations. Herein, we report a NSCLC patient with EGFR exon 19 deletion treated with EGFR-TKI. During treatment, the pathological type of tumor showed transformation from NSCLC to combined SCLC and then to pure SCLC after acquiring EGFR-TKI resistance. Genomic analysis revealed that the EGFR exon 19 deletion, TP53 Y220H mutation, and retinoblastomal transcriptional corepressor 1 (RB1) F755V mutation existed persistently. Immunohistochemical results showed the loss of EGFR and RB1 expression in SCLC. The patient received multi-line chemotherapy with platinum agents and experienced a briefly effective window, but died of aggressive tumor progression. We profiled the transformation from NSCLC to SCLC of this case and pointed out the importance of repeat biopsy in response to EGFR-TKI resistance. Our results showed a novel RB1 F755V mutation which may be associated with RB1 loss. This report summarized the clinical characteristics, mechanisms, and predictors of SCLC transformation, and discussed the treatment after transformation.

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.

[Research Advances on Transformation to Small Cell Lung Cancer]

小细胞肺癌（small cell lung cancer, SCLC）转化是非小细胞肺癌尤其是表皮生长因子受体（epidermal growth factor receptor, EGFR）突变患者的重要耐药机制之一。目前发现转化性SCLC具有与原发性SCLC相似的临床特征，对化疗短期有效，中位生存期仅1年左右。RB1缺失、体细胞拷贝数改变与SCLC转化有关，但发生SCLC转化的确切分子机制仍不完全清楚。转化性SCLC的治疗也面临巨大的挑战，针对SCLC的化疗方案是目前的主要治疗选择，联合治疗、局部治疗以及预防SCLC转化的策略也在探索。本文将转化性SCLC的临床特征、分子机制和治疗选择进行综述。

Adequacy of samples obtained via percutaneous core-needle rebiopsy for EGFR T790M molecular analysis in patients with non-small cell lung cancer following acquired resistance to first-line therapy: A systematic review and meta-analysis

MICRO ABSTRACT

Rebiopsies characterizing resistance mutations in patients with non-small cell lung cancer (NSCLC) can guide personalized medicine and improve overall survival rates. In this systematic review, we examine the suitability of percutaneous core-needle biopsy (PT-CNB) to obtain adequate samples for molecular characterization of the acquired resistance mutation T790M. This review provides evidence that PT-CNB can obtain samples with high adequacy, with a mutation detection rate that is in accordance with prior literature.

BACKGROUND

Non-small cell lung cancer (NSCLC) comprises 85% of all lung cancers and has seen improved survival rates with the rise of personalized medicine. Resistance mutations to first-line therapies, such as T790M, however, render first-line therapies ineffective. Rebiopsies characterizing resistance mutations inform therapeutic decisions, which result in prolonged survival. Given the high efficacy of percutaneous core-needle biopsy (PT-CNB), we conducted the first systematic review to analyze the ability of PT-CNB to obtain samples of high adequacy in order to characterize the acquired resistance mutation T790M in patients with NSCLC.

METHODS

We performed a comprehensive literature search across PubMed, Embase, and CENTRAL. Search terms related to "NSCLC," "rebiopsy," and "PT-CNB" were used to obtain results. We included all prospective and retrospective studies that satisfied our inclusion and exclusion criteria. A random effects model was utilized to pool adequacy and detection rates of the chosen articles. We performed a systematic review, meta-analysis, and meta-regression to investigate the adequacy and T790M detection rates of samples obtained via PT-CNB.

RESULTS

Out of the 173 studies initially identified, 5 studies met the inclusion and exclusion criteria and were chosen for our final cohort of 436 patients for meta-analysis. The pooled adequacy rate of samples obtained via PT-CNB was 86.92% (95% CI: [79.31%, 92.0%]) and the pooled T790M detection rate was 46.0% (95% CI: [26.6%, 66.7%]). There was considerable heterogeneity among studies (I² > 50%) in both adequacy and T790M detection rates.

CONCLUSION

PT-CNB can obtain adequate samples for T790M molecular characterization in NSCLC lung cancer patients. Additional prospective studies are needed to corroborate the results in this review.

Comprehensive analysis of treatment modes and clinical outcomes of small cell lung cancer transformed from epidermal growth factor receptor mutant lung adenocarcinoma

Background

Transformation to small cell lung cancer (SCLC) is a resistance mechanism of epidermal growth factor receptor (EGFR) mutant lung adenocarcinoma (LADC) patients treated with EGFR tyrosine kinase inhibitors (TKIs). Here, we describe the clinical characteristics and prognosis of these patients and explore the treatment modes after transformation.

Methods

EGFR‐mutant LADC patients with SCLC transformation were retrospectively included in the study. Demographic and clinical data were collected. Survival outcomes and corresponding influential factors were analyzed.

Results

Twenty‐nine patients were included in the study. The median progression‐free survival (PFS) of patients who received first‐line EGFR‐TKIs was 13.1 months. The median time to SCLC transformation was 27.5 months. After transformation, the objective response rates of patients who received first‐line chemotherapy with or without EGFR‐TKIs were 43.8% and 37.5%, respectively. The median PFS of patients reveiving chemotherapy with EGFR‐TKIs was significantly longer than that of patients receiving chemotherapy without EGFR‐TKIs (5.2 vs. 3.0 months; HR, 0.19; 95% CI: 0.05–0.72; p = 0.014). However, there was no significant difference in median overall survival (OS) between patients who received chemotherapy with or without EGFR‐TKIs (14.8 vs. 13.0 months; p = 0.474). In the multivariate Cox proportional hazards regression analysis, both anti‐angiogenic treatment (HR, 0.04; 95% CI: 0.01–0.29; p = 0.001) and local radiotherapy (HR, 0.28; 95% CI: 0.08–0.97; p = 0.044) were significantly associated with better patient OS after transformation.

Conclusions

Compared with chemotherapy alone, the combination of chemotherapy and EGFR‐TKIs as first‐line treatment after SCLC transformation can benefit patients in PFS but not in OS. However, anti‐angiogenic therapies and local radiotherapy can significantly prolong OS after transformation.

Effective early diagnosis for NSCLC: an algorithm

INTRODUCTION

Lung cancer still remains undiagnosed for most patients until the disease is inoperable.

AREAS COVERED

We performed search on PubMed with the keywords: EBUS, radial-EBUS, bronchoscopy, lung cancer, electromagnetic navigation, ct-biopsy, transthoracic biopsy. We present diagnostic equipment and imaging techniques such as positron emission tomography, endoscopical navigation systems, endobronchial ultrasound, radial-endobronchial ultrasound, transthoracic ultrasound biopsy, and computed tomography guided biopsies.

EXPERT OPINION

However, lack of early disease symptoms remains the most important issue and therefore we should direct our efforts to screening and early disease diagnosis. An algorithm is proposed for biopsy upon initial disease diagnosis.

Small-cell lung cancer transformation from EGFR-mutant adenocarcinoma after EGFR-TKIs resistance: A case report

RATIONALE

With the recent advancements in molecular biology research, epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have emerged as excellent therapies for patients with EGFR-mutant cancers. However, these patients inevitably develop cross-acquired resistance to EGFR-TKIs. Transformation to small-cell lung cancer (SCLC) is considered a rare resistance mechanism against EGFR-TKI therapy. Here, we report a case of TKI resistance due to SCLC transformation and demonstrate its mechanisms and clinical features.

PATIENT CONCERNS

A 54-year-old Chinese man with a history of smoking for 40 years complained of an intermittent cough in March 2019.

DIAGNOSIS

Transbronchial lung biopsy was performed on the basal segment of the left lower lobe, which confirmed lung adenocarcinoma. In January 2020, repeat biopsy was performed, and the results of immunohistochemistry (IHC) staining showed TTF-1 (+), CK7 (+), napsin A (+), syn (+), and CD56 (+), with a Ki-67 (+) index 80% of small cell carcinomas. Infiltrating adenocarcinomas and small cell carcinomas were observed.

INTERVENTIONS

Icotinib (125 mg thrice daily) was administered as a first-line treatment from June 2019. We subsequently administered a chemotherapy regimen consisting of etoposide (180 mg, days 1-3) plus cisplatin (45 mg, days 1-3) every 3 weeks for 1 cycle after recurrence. As the patient could not tolerate further chemotherapy, he continued taking icotinib orally and received whole-brain radiotherapy 10 times to a total dose of 30 Gy after brain metastases.

OUTCOMES

The patient relapsed after successful treatment with icotinib for 9 months. A partial response was achieved after 4 cycles of chemotherapy, and despite the brief success of chemotherapy, our patient exhibited brain metastasis and metastases of the eleventh thoracic spine and the second lumbar vertebra with pathological fracture. The patient eventually died of aggressive cancer progression.

LESSONS

Our case highlights the possibility of SCLC transformation from EGFR-mutant adenocarcinoma and the importance of repeat biopsy for drug resistance. Serum neuron-specific enolase levels may also be useful for detecting early SCLC transformation.