Traversing through the Dynamic Protein-Protein Interaction Landscape and Conformational Plasticity of PD-1 for Small-Molecule Discovery

Monoclonal antibodies (mAbs) blocking the PD-1/PD-L1 interface have shown remarkable success in treating malignancies, but they may also initiate lethal immune-related adverse events. Small molecules may circumvent the mAb limitations; however, none has entered clinical trials targeting PD-1. Its complex protein-protein interaction interfaces necessitate an atomic-level understanding of recognition and binding mechanisms. Hence, we have aimed to highlight the PD-1's sequence-structure-dynamic-function link with its cognate ligands and diversely reported inhibitors. We focus primarily on the anti-PD-1 mAbs, their mode of actions, and interactions with PD-1 epitopes. The comparison of co-crystals showed that these ligands/inhibitors harness the PD-1's conformational plasticity and structural determinants differentially. The relationship between modulator binding patterns and biological activity is demonstrated using interaction fingerprinting of all reported human PD-1 co-crystals. The significant dynamical events and hot-spot residues underpinned from crystallographic wealth and computational studies have been highlighted to expedite small-molecule discovery.

Immuno-related endocrinopathy in patients treated with immune checkpoint inhibitors

Recently immune checkpoint inhibitors amazingly changed the landscape of cancer therapy worldwide. The number of immune checkpoint molecules in clinical practice is constantly increasing. There are some monoclonal antibodies recently registered in the Russian Federation: anti-PD1 antibodies (nivolumab, pembrolizumab), anti-PD-L1 (atezolizumab, durvalumab), anti-CTLA-4 (ipilimumab). Immune-mediated endocrinopathies are some of the most common complications of immunotherapy. According to the results of clinical studies, the incidence of serious endocrine immuno-mediated adverse events with anti-PD1 monoclonal antibodies is low (3.5–8%). The use of anti-CTLA4 antibodies, combined regimens, and the use of immunotherapy after chemoradiotherapy significantly increase the incidence of serious adverse events to 30%. In clinical practice of N.N. Blokhin Cancer Research Center among 245 non-small cell lung cancer and hepatocellular carcinoma patients treated with immunotherapy, 22 (8,9%) developed an immune-mediated endocrinopathy. Most patients developed adverse events of 1–2 degrees, in two patients – 3 degrees, requiring discontinuation of treatment. The aim of this article was to provide useful information and recommendations regarding the management of common immuno-related endocrine adverse events (including hypothyroidism, hyperthyroidism, pituitary, adrenal insufficiency) for clinical oncologists.

Clinical and Recent Patents Applications of PD-1/PD-L1 Targeting Immunotherapy in Cancer Treatment-Current Progress, Strategy, and Future Perspective

Targeting PD-L1 and PD-1 interactions is a relatively new therapeutic strategy used to treat cancer. Inhibitors of PD-1/PD-L1 include peptides, small molecule chemical compounds, and antibodies. Several approved antibodies targeting PD-1 or PD-L1 have been patented with good curative effect in various cancer types in clinical practices. While the current antibody therapy is facing development bottleneck, some companies have tried to develop PD-L1 companion tests to select patients with better diagnosis potential. Meanwhile, many companies have recently synthesized small molecule inhibitors of PD-1/PD-L1 interactions and focused on searching for novel biomarker to predict the efficacy of anti-PD-1/PD-L1 drugs. This review summarized clinical studies and patent applications related to PD-1/PD-L1 targeted therapy and also discussed progress in inhibitors of PD-1/PD-L1.