The Efficacy and Safety of Narlumosbart in Combination With Stereotactic Body Radiation Therapy to Improve the Efficacy of First-line Chemotherapy Combined With Immunotherapy in Patients With Bone Metastases From Advanced Non-small Cell Lung Cancer

Introduction: Immunotherapy in combination with chemotherapy have been recommended as the first-line treatment of driver-negative advanced non-small cell lung cancer (NSCLC), but the efficacy is worse in NSCLC patients with bone metastases due to the immunosuppressive microenvironment. Studies have shown that not only the nuclear factor kappa-B ligand (RANKL) inhibitors but also Stereotactic Body Radiation Therapy (SBRT) play a significant role in improving the tumor immune microenvironment. Therefore, narlumosbart，a monoclonal antibody (mAb) targeting RANKL，in combination with SBRT may have synergistic effects and improve efficacy of immunotherapy and chemotherapy in driver-negative advanced NSCLC patients with bone metastases. Methods: This single-arm, single-center phase II clinical trial will enroll NSCLC patients with bone metastases who have not received any systemic therapy. Patients will receive narlumosbart and bone target lesion SBRT in combination with first-line treatment immunotherapy and chemotherapy after screening eligible subjects. Narlumosbart, 120mg/time, subcutaneous injection, is administered every 4 weeks. For the treatment of SBRT for bone metastases, the dose of 24Gy/3F is used for spinal metastases, and 30Gy/5F or 35Gy/5F is used for non-spinal lesions. Chemotherapy combined with immune checkpoint inhibitor therapy was used in accordance with the guidelines. The primary endpoint is to assess the objective response rate of NSCLC patients with bone metastases from narlumosbart combined with SBRT and first-line chemotherapy and immunotherapy. The secondary endpoints include progression-free survival, overall survival and safety. Sample size calculation used the Simon Two-Stage method. 9 patients will be enrolled in the first stage. If ≥ 2 patients achieve CR/PR, the second stage of enrollment will be performed. If only 2 patients \< achieve CR/PR, the trial will be terminated. In the second phase, 15 patients will be enrolled. 27 subjects will be enrolled in this project, considering the dropout rate of 10%. Wangjun Yan AND Zhengfei Zhu are the Co-Principal Investigators of this study.