Research progress of anti-angiogenic therapy combined with immunotherapy and radiotherapy for the treatment of brain metastases in non-small cell lung cancer (Review).

The treatment of brain metastases (BMs) from non-small cell lung cancer (NSCLC) is primarily systemic and local; however, the therapeutic effects of various treatment methods on BMs are minimal. The occurrence of BMs from NSCLC is a complex process. The penetration of tumour cells into the blood-brain barrier changes the function of cell junctions, leading to changes in the microenvironment of intracranial tumours. Antitumour therapies such as immunotherapy (IT), chemotherapy, targeted therapy and radiotherapy (RT) all affect the tumour immune microenvironment (TIM). Anti-angiogenic drugs (AADs) normalize blood vessels and improve access to the tumours, which is an effective strategy for combination IT. IT combined with RT improves the survival rate in patients with BMs and reduces the risk of brain failure and nervous system mortality. AADs can markedly alleviate radiation-induced brain injury after RT. Furthermore, anti-angiogenic therapy can regulate the immune checkpoint inhibitor-mediated microenvironment of intracranial tumours. Combining these three factors may improve the prognosis of patients with NSCLC and BMs. However, there is no reliable evidence on the safety and efficacy of their combination therapy. Therefore, the present article reviews the effects of AADs combined with IT and RT on the TIM of patients with NSCLC with BMs and the clinical application progress in order to provide ideas for the treatment of NSCLC with BMs.