Gu-Jin-Xiao-Ji Decoction potentiates anti-PD-1 immunotherapy in lung cancer by inhibiting the PI3K/AKT/NF-κB/PD-L1 axis.

This study aims to elucidate the molecular mechanisms by which the traditional Chinese medicine Gu-Jin-Xiao-Ji Decoction (GJXJD) enhances the anti-tumor efficacy of PD-1 inhibitors in lung cancer and to characterize its major chemical components. The major components of GJXJD were identified and quantitatively analyzed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). A mouse Lewis lung carcinoma (LLC) subcutaneous xenograft model was established, and high-throughput transcriptome sequencing was performed. Combined treatment with GJXJD and a PD-1 inhibitor significantly suppressed tumor growth, achieving a tumor inhibition rate of 54.48 %, which was substantially higher than that of either monotherapy (GJXJD: 27.58 %; anti-PD-1: 25.76 %). Transcriptomic analysis indicated notable enrichment and downregulation of the PI3K/AKT signaling pathway. Immunohistochemistry revealed inhibition of the PI3K/AKT/NF-κB axis and subsequent downregulation of PD-L1 expression. GJXJD treatment increased spleen and thymus indices, reduced serum IL-17 levels by approximately 40 %, and promoted the secretion of IL-2, IFN-γ, and TNF-α by about 1.5- to 2-fold. Enhanced infiltration of CD3+, CD4+, and CD8+ T cells were observed in tumor tissues, with CD8+ T cell infiltration increasing by over 3-fold in the combination group. H&E staining showed no significant pathological changes in major organs. These findings demonstrate that GJXJD potentiates the anti-tumor effect of PD-1 inhibitors by inhibiting the PI3K/AKT/NF-κB pathway, reducing PD-L1 expression, and ameliorating immune evasion. The identified active components provide a chemical basis for its efficacy, supporting GJXJD as a promising adjuvant agent for lung cancer immunotherapy.