The Clinicopathological Features of BRG1-deficient Non-small Cell Lung Cancer and Its Response to Immunotherapy: A Single-center Retrospective Study
Abstract PurposeBRG1-deficient NSCLCs have been more intriguing recently for its highly aggressive clinical behavior and no effective therapies. This study characterized the clinical and pathological features of BRG1-deficient NSCLCs and investigated their response to immunotherapy.MethodsForty-seven cases with BRG1-deficient NSCLC were included. Immunohistochemical markers such as CK7, TTF-1, NapsinA, P40, HepPar-1, Ki-67, BRM, ARID1A and ARID1B were stained. Meanwhile, the PD-L1 expression level, overall survival, progression-free survival and disease control rate of patients received immunotherapy were evaluated.ResultsThis study revealed that: (1) Patients with BRG1-deficient NSCLC have a male predominance(89.4%), smoker enrichment(76.6%) and poor prognosis(median OS: 7.0 months for advanced stage). (2) Histologically, BRG1-deficient NSCLCs presented significant morphological diversity and no lepidic pattern. Inflammatory infiltration and tumor necrosis was a prominent feature. Immunohistochemical analyses showed a distinctive uniform immunophenotype (TTF-1-/NapsinA-/CK7+) in 60.9% (28/46) of cases and HepPar-1 positive in 46.5% (20/43) of cases. BRM loss or significant reduction coexisted in 11.8% (4/34) of cases. No case (0/37) showed loss of ARID1A or ARID1B. (3) For twenty-nine patients with advanced stage, eight patients had received immunotherapy and 4 cases achieved a sustainable clinical response with the disease control rate of 50%. ICIs treated patients had better OS than those who received non-ICIs treatment settings (median OS, 27.0m versus 6.0m, p=0.02). Moreover, patients received ICIs have a median PFS of 17.0 months, while, median PFS on platinum doublet chemotherapy were only 6.0 months(p=0.04). ConclusionBRG1-deficient NSCLC showed diverse histopathological patterns and a unique immunohistochemical phenotype. ICIs–based immunotherapy was a beneficial therapy for BRG1- deficient NSCLC.