Effective personalized treatment of metastatic non-small cell lung cancer (NSCLC) hinges on precise molecular characterization, encompassing the identification of targetable driver mutations and the assessment of programmed death-ligand 1 (PD-L1) expression. The presence of a targetable driver mutation holds significant prognostic and predictive value, paving the way for highly effective first-line targeted therapy using kinase inhibitors. These oral medications often demonstrate superior tolerability compared to platinum-based doublet chemotherapy and immunotherapy, making them suitable even for frail patients or those with comorbidities. In the absence of targetable driver mutations or contraindications to immunotherapy, the choice of first-line treatment depends largely on PD-L1 expression. A PD-L1 expression of ≥50% typically warrants Pembrolizumab or Cemiplimab monotherapy, while platinum-based doublet chemotherapy combined with Pembrolizumab or Atezolizumab is indicated for PD-L1 <50% expression. Therefore, achieving comprehensive molecular and immunohistochemical characterization is crucial for optimal NSCLC management. However, obtaining adequate tissue samples can be challenging due to tumor size, location, and accessibility. In cases of mediastinal or hilar lymph node involvement, EBUS-TBNA (endobronchial ultrasound-guided transbronchial needle aspiration) might confirm malignancy, but the low cellularity of cytological samples often limits precise immunocytochemical and molecular characterization. Endobronchial and transbronchial cryobiopsy techniques offer an advantage by yielding larger tissue samples suitable for detailed analysis. EBUS-TBLNC (EBUS-guided transbronchial lymph node cryobiopsy), although technically demanding, has shown promise in providing sufficient tissue for comprehensive characterization in individual cases and small series. This case report details a patient where multiple biopsy attempts proved insufficient, highlighting the potential of EBUS-TBLNC to overcome these limitations and enable personalized treatment.

The literature extensively supports the importance of accurate molecular characterization for optimal NSCLC treatment. Several studies have demonstrated the efficacy of targeted therapies for patients with specific driver mutations (e.g., EGFR, ALK) and the benefit of immunotherapy based on PD-L1 expression levels. However, challenges in obtaining sufficient high-quality tissue for comprehensive testing remain a significant hurdle. Existing research indicates that EBUS-TBNA, while useful for initial diagnosis, often yields insufficient material for in-depth molecular profiling. Conversely, cryobiopsy techniques, including EBUS-TBLNC, have shown promise in overcoming this limitation by providing larger and better-preserved tissue samples. Although EBUS-TBLNC is a relatively new technique, initial case series and studies suggest improved diagnostic yields compared to traditional methods. This aligns with the findings of this case report, which highlights the value of EBUS-TBLNC in situations where other methods have failed to provide adequate tissue for a comprehensive molecular work-up.

This case report describes the diagnostic and treatment journey of an 83-year-old male former smoker with a history of multiple comorbidities and an ECOG performance status of 1. The patient presented with a symptomatic left pleural effusion, which led to the discovery of a lung lesion in the left lower lobe, lymphangiosis, and mediastinal lymphadenopathy. Initial pleural fluid analysis revealed single cells of a TTF-1-positive pulmonary adenocarcinoma, but insufficient material for further molecular testing. Subsequently, EBUS-TBNA was performed on mediastinal lymph node 4L, but despite adequate material on rapid on-site evaluation, malignant cells were not identified. A CT-guided transthoracic biopsy also failed to yield sufficient tumor cells for next-generation sequencing (NGS). Due to cardiovascular comorbidities increasing the risk associated with mediastinoscopy and the patient's refusal, along with the low likelihood of actionable molecular alterations being detected via liquid biopsy, EBUS-TBLNC was proposed. The patient gave informed consent, understanding the potential side effects and limited clinical experience with this procedure. Under EBUS guidance, the bronchial wall was tunnelled towards lymph node 4L using a monopolar electric needle knife. A 1.1 mm cryoprobe was inserted into the lymph node and freezing was performed for 7 seconds. Multiple biopsies were extracted, with a combined size of 0.8 × 0.7 × 0.4 cm. The procedure was well-tolerated without complications. The EBUS-TBLNC sample revealed extensive infiltrates of TTF1-positive adenocarcinoma cells. Comprehensive molecular characterization involving NGS, immunohistochemistry, and FISH analysis identified a pathogenic TP53 mutation in exon 8 but no targetable genetic alterations. However, immunohistochemistry showed 100% PD-L1 reactivity using the Ventana SP263 assay. Based on these findings, first-line PD-1-directed therapy with Pembrolizumab monotherapy was initiated. Unfortunately, the patient experienced intercurrent medical issues unrelated to the tumor or treatment, leading to repeated hospitalizations and eventual discontinuation of immunotherapy when his ECOG performance status deteriorated to 3. He ultimately succumbed to the disease five months after receiving the first Pembrolizumab dose.

This case highlights the challenges in obtaining sufficient tumor tissue for comprehensive molecular characterization in NSCLC, even with advanced imaging and common sampling techniques. Multiple initial attempts (pleural fluid analysis, EBUS-TBNA, and CT-guided transthoracic biopsy) failed to yield adequate tumor material for detailed molecular analysis, including NGS and PD-L1 expression assessment. Only the EBUS-TBLNC procedure provided a large enough and high-quality tissue sample enabling complete molecular and immunohistochemical characterization. This analysis revealed the absence of actionable genetic alterations but a strong, 100% PD-L1 expression in the tumor cells. Based on these findings, the decision was made to initiate immunotherapy with Pembrolizumab, reflecting a personalized treatment approach guided by the comprehensive molecular data obtained exclusively via EBUS-TBLNC. While the patient's overall outcome was ultimately poor due to intercurrent illnesses and tumor progression, the case underscores the pivotal role of EBUS-TBLNC in enabling accurate characterization and subsequent personalized treatment. The fact that the patient was elderly and had multiple comorbidities further strengthens the value of obtaining conclusive results with minimal invasive procedures such as EBUS-TBLNC.

This case underscores the limitations of traditional biopsy techniques in obtaining sufficient tumor tissue for comprehensive molecular characterization in NSCLC, especially when dealing with mediastinal lymph node involvement. The success of EBUS-TBLNC in providing a high-quality sample that allowed for the identification of PD-L1 expression, leading to immunotherapy, highlights its potential as a valuable tool in this setting. While the patient's outcome was ultimately unfavorable, the successful use of EBUS-TBLNC emphasizes its role in enabling personalized therapy based on precise molecular profiling. The relatively low invasiveness of the EBUS-TBLNC procedure makes it attractive for elderly or frail patients and avoids the need for more invasive methods like mediastinoscopy. Further studies evaluating the effectiveness and broader applicability of EBUS-TBLNC in NSCLC characterization are needed.

This case report demonstrates that EBUS-guided transbronchial lymph node cryobiopsy (EBUS-TBLNC) can be a crucial technique for obtaining adequate tumor samples in NSCLC patients when traditional methods are unsuccessful. The ability to perform comprehensive molecular and immunohistochemical analysis led to personalized immunotherapy, highlighting the importance of this minimally invasive procedure. Further research should investigate the wider applicability of EBUS-TBLNC in NSCLC diagnosis and treatment optimization, particularly in cases with challenging tumor localization or limited tissue availability.

This is a single-case report, limiting the generalizability of the findings. The patient's outcome was influenced by intercurrent medical issues, making it difficult to determine the efficacy of the Pembrolizumab treatment definitively. The small sample size and retrospective nature of the study limit broader conclusions about the routine clinical utility of EBUS-TBLNC. Further prospective studies involving larger cohorts are warranted to establish the effectiveness and optimal application of this procedure.