Efficacy of Pembrolizumab and Nivolumab in Crossing the Blood Brain Barrier

Metastatic brain tumors are the leading cause of central nervous system malignancies in adults, surpassing primary central nervous system with non-small cell lung cancer, accounting for more than 50% of all cases. The emergence of immunotherapies such as antibodies targeting the immune check points has led to significant advancement in the field of cancer treatment since these approaches have overwhelmingly impacted outcomes in patients with metastatic non-small cell lung cancer. Here we report two cases of metastatic non-small cell lung cancer treated with immunotherapy. While one patient achieved an excellent systemic response but developed new metastatic brain lesions, the other showed remarkable systemic as well as central response. These cases highlight variable central nervous system penetration of programmed death 1 (PD-1) antibodies, and we also review the available literature on blood brain barrier permeability of PD-1 antibodies.