Histological transformation of non-small cell lung cancer:Clinical analysis of nine cases

BACKGROUND Histological transformation is one of the numerous mechanisms of acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors(EGFRTKIs).Given its rarity,the underlying transformational mechanisms,clinical features,and therapeutic prognoses are only studied through limited case reports.AIM To analyze the clinical characteristics and underlying mechanisms in non-small cell lung cancer(SCLC)patients with histological transformation after treatment with EGFR-TKIs.METHODS We retrospectively investigated nine patients diagnosed with non-SCLC transforming to SCLC,large-cell neuroendocrine carcinoma(LCNEC),or squamous cell carcinoma on re-biopsy after first-or third-generation EGFR-TKIs.RESULTS The median age of nine patients was 60 years.Among them,six patients had the EGFR 19del mutation,one had the L858R mutation,and one had wild-type EGFR.The level of plasma NSE was measured in six patients with SCLC or LCNEC transformation when transformation occurred,and five patients had elevated plasma NSE levels.All patients received standard chemotherapy after transformation with the exception of one patient who received chemotherapy and anlotinib.CONCLUSION Tumor re-biopsy should be performed routinely when EGFR-TKI therapy fails in lung cancer patients to avoid ignoring histological transformation and to select a subsequent therapeutic strategy.The transformed tumor retained the original EGFR mutation,indicating that histological transformation represents an evolution from the initial tumor.

Molecular Therapeutics of Non-Small Cell Lung Cancer (NSCLC) and Challenges in Repeat Tissue Biopsy

With advances in targeted and personalized treatment for lung cancer, molecular analysis of tumors is routinely performed for sequencing of treatment options in patients with advanced non-small-cell lung cancer (NSCLC). Oncogene addiction due to driver mutations includes EGFR exon 20 insertion mutations, MET amplification, EML4-AL, KRAS G12C point mutations, RET rearrangements, HER2 amplification and mutations, and FGFR amplification and translocations. A re-biopsy at the time of tumor recurrence or progression after first-line treatment failure is important for further molecular assessment and personalized therapy. However, repeat tumor biopsies are fraught with challenges including access to the tumor, sample inadequacy, patient consent, patient performance status, safety, or physician’s choice or assessment. Cytological specimens are gaining importance but are limited due to validation difficulties. Liquid biopsies, which are minimally invasive have shown promise to assess dynamic biomarkers using ctDNA analysis and are thus frequently considered in routine clinical practice in advanced NSCLC patients to guide further targeted treatment. Here we present a comprehensive review that emphasizes the significance of performing tumor re-biopsy in advanced stage NSCLC patients following resistance to first-line treatment and simultaneously highlights the current challenges in performing the same and the current status and future perspectives of liquid biopsy in NSCLC.