RBM17 Expression Is Associated With the Efficacy of ICI Monotherapy in NSCLC With Low PD-L1 Expression.

BACKGROUND/AIM: Immune checkpoint inhibitors (ICIs) are currently a standard treatment tool for non-small cell lung cancer (NSCLC). RNA-binding motif protein 17 (RBM17), a splicing factor, is frequently over-expressed in NSCLC, but little is known about the role of RBM17 in the efficacy of ICIs for NSCLC. Thus, we investigated the correlation between RBM17 expression and ICI efficacy in NSCLC. PATIENTS AND METHODS: Biopsy or surgical specimens were collected from patients with advanced or recurrent NSCLC who received ICI monotherapy or chemo-immunotherapy in a first-line setting. RBM17 expression was examined using immunohistochemistry. The correlation between the efficacy of ICI monotherapy or chemo-immunotherapy and RBM17 expression was evaluated. RESULTS: Among the 218 cases, 115 (52.8%) cases were positive for RBM17 expression. RBM17 expression was not associated with the objective response rate (ORR) or progression-free survival (PFS) in either of the ICI monotherapy or chemo-immunotherapy groups. However, among those with a low PD-L1 expression level (PD-L1 <50%; n=86), RBM17 expression was significantly associated with a better ORR (p=0.045) and a better PFS (p<0.001) in the ICI monotherapy group, and was significantly associated with a poor ORR in the chemo-immunotherapy group (p=0.041). CONCLUSION: RBM17 might be a useful predictive marker for a higher efficacy of ICI monotherapy in NSCLC patients with a low PD-L1 expression level.

Tract creation with a 25-gauge needle for convex endobronchial ultrasound-guided core biopsy in intrapulmonary lesions adjacent to bronchi: three case reports.

Background: The use of endobronchial ultrasound-guided core biopsy (EBUS-CB) using forceps or cryoprobes to obtain true histological samples has improved the diagnostic yield for mediastinal and hilar lymphadenopathy. Tract creation in the bronchial wall of the central airway is primarily performed using electrocautery devices in EBUS-CB; however, their poor maneuverability and the risk of vascular injury and damage to the tip of the bronchoscope have prevented the application of EBUS-CB for diagnosing intrapulmonary lesions beyond the central locations. This report presents three cases wherein a 25-gauge transbronchial needle aspiration (TBNA) needle with high flexibility and safety was used to create a tract in the bronchial wall for EBUS-CB of the intrapulmonary lesions adjacent to the bronchi. Case Description: In all cases, EBUS-TBNA using a 25-gauge TBNA needle was performed on the intrapulmonary lesions adjacent to the bronchi, followed by EBUS-CB with 1.9-mm forceps in two cases and also with a 1.1-mm cryoprobe in one case. The EBUS-TBNA specimens revealed no abnormality or only a small number of tumor cells. However, subsequent EBUS-CB, through the tract created by EBUS-TBNA, enabled the collection of a sufficient amount of histological samples with well-preserved histoarchitecture. The histological diagnosis was made via immunostaining, and multigene mutation testing was also successfully analyzed. Conclusions: The use of a 25-gauge needle for creating a tract allows EBUS-CB for the intrapulmonary lesions and may allow for the collection of sufficient histological samples for biomarker analysis and tissue diagnosis.