Patients diagnosed with malignant lymphoma have lymphadenopathy and sometimes hepatosplenomegaly or infiltration of other organs, including the bone marrow. These intratumoral T cells are simply residual elements of normal lymphoid tissue at lymphoma sites or are antitumor immune response.

Additional immune cells present are monocytes, macrophages, natural killer cells, and dendritic cells. PD-1 signalling results in negative T-cell function regulation, and the engagement of the PD-1 receptor by its ligands results in T cells becoming senescent and subsequently apoptotic.

Monoclonal antibodies have developed that bind to PD-1 or PD-L1 and block the interaction between the ligands and the PD-1 receptor. The trial enrolled 66 eligible patients, and the primary endpoint of the study was an assessment of progression-free survival (PFS) at 16 months. The study found that PFS in this subset of patients at 16 months was 70%, which met the study’s predetermined endpoint.

The promising initial clinical trial results were confirmed in larger phase II trials. Additional antibodies targeting either PD-1 or PD-L1 developed were tested. The approved indication for single-agent PD-1 inhibition is likely to be in patients with relapsed and refractory Hodgkin lymphoma. 

In conclusion, clinical results with PD-1 inhibition have been promising, particularly in patients with Hodgkin lymphoma, high response rate, and durable. With the hope that patients will benefit from treatment, many patients cured their disease by harnessing the body’s immune response.