Histological conversion from adenocarcinoma to small cell carcinoma of the lung after treatment with an immune checkpoint inhibitor: a case report

Potential therapeutic option for EGFR-mutant small cell lung cancer transformation: a case report and literature review

Transformation from non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is rare and is associated with poor prognosis. However, the standard treatment protocols for patients with SCLC transformation remain unknown. Here, we report the case of a patient with advanced EGFR exon 19 deletion (19del) NSCLC who underwent SCLC transformation during targeted therapy. Biopsies and genetic testing were performed to adjust treatment regimens accordingly. The patient responded favorably to a combined treatment regimen comprising etoposide plus cisplatin chemotherapy and adebrelimab plus osimertinib. This case highlights the critical importance of acknowledging tumor heterogeneity in clinical decision-making and identifying potentially effective treatment options for patients with SCLC transformation. Additionally, we reviewed cases of the transformation of NSCLC to SCLC from 2017 to 2023.

Comprehensive molecular and clinical insights into non-small cell lung cancer transformation to small cell lung cancer with an illustrative case report

Histologic transformation to small cell lung cancer (tSCLC) is a rare but increasingly recognised mechanism of acquired resistance to tyrosine kinase inhibitors (TKI) in patients with epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC). Beyond its acknowledged role in TKI resistance, histologic transformation to SCLC might be an important, yet under-recognised, mechanism of resistance in NSCLC treated with immunotherapy. Our review identified 32 studies that investigated tSCLC development in patients with EGFR-mutated NSCLC treated with TKI therapy and 16 case reports of patients treated with immunotherapy. It revealed the rarity of tSCLC, with a predominance of EGFR exon 19 mutations and limited therapeutic options and outcomes. Across all analysed studies in EGFR-mutated NSCLC treated with TKI therapy, the median time to tSCLC development was ∼17 months, with a median overall survival of 10 months. Histologic transformation of EGFR-mutated NSCLC to SCLC is a rare, but challenging clinical problem with a poor prognosis. A small number of documented cases of tSCLC after immunotherapy highlight the need for rebiopsies at progression to diagnose this potential resistance mechanism. Further research is needed to better understand the mechanisms underlying this phenomenon and to develop more effective treatment strategies for patients with tSCLC.

Histomorphological transformation from non-small cell lung carcinoma to small cell lung carcinoma after targeted therapy or immunotherapy: A report of two cases

Molecular targeting and immunotherapy provide durable responses for advanced lung cancer clinical therapy in many patients. However, the mechanisms of occurrence of progressive disease and resistance to targeted therapy and immunotherapy have not been elucidated. Herein, we report two cases of small cell transformation of non-small cell lung cancer (NSCLC) after targeted therapy or immunotherapy. The first case was a 63-year-old female patient presenting with cough and expectoration. Left lung invasive adenocarcinoma was diagnosed after left lung tumor biopsy. After epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) targeted therapy for almost 2 years, disease progression and symptom aggravation were observed. Pathological and immunohistochemical staining results after biopsy revealed small cell lung cancer (SCLC). The second case was a 75-year-old male patient diagnosed with stage IV squamous cell carcinoma of the lung, who received carboplatin/paclitaxel adjuvant chemotherapy and pembrolizumab treatment with partial response. Disease progression and metastasis occurred within 15 cycles of immunotherapy. Computed tomography revealed a lower left lung tumor. Cytological examination of lung lavage fluid and biopsy under thoracoscope revealed SCLC. In conclusion, histological transformation to SCLC is a potential mechanism of NSCLC resistance to targeted therapy or immunotherapy. During treatment, clinicians should monitor serum tumor markers or genome sequencing, particularly in patients with disease progression, as this may be beneficial for early detection of SCLC transformation. Repeated biopsy can be performed if necessary, and the therapeutic regimen can be adjusted in a timely manner according to the results of molecular pathological tests for personalization and whole-process management.

Analysis of neuroendocrine clones in NSCLCs using an immuno-guided laser-capture microdissection-based approach

Clonal evolution and lineage plasticity are key contributors to tumor heterogeneity and response to treatment in cancer. However, capturing signal transduction events in coexisting clones remains challenging from a technical perspective. In this study, we developed and tested a signal-transduction-based workflow to isolate and profile coexisting clones within a complex cellular system like non-small cell lung cancers (NSCLCs). Cooccurring clones were isolated under immunohistochemical guidance using laser-capture microdissection, and cell signaling activation portraits were measured using the reverse-phase protein microarray. To increase the translational potential of this work and capture druggable vulnerabilities within different clones, we measured expression/activation of a panel of key drug targets and downstream substrates of FDA-approved or investigational agents. We isolated intermixed clones, including poorly represented ones (<5% of cells), within the tumor microecology and identified molecular characteristics uniquely attributable to cancer cells that undergo lineage plasticity and neuroendocrine transdifferentiation in NSCLCs.