Abstract 6528: Anti-PD-1 induces the endocytosis of the co-receptor from the surface of T-cells: Nivolumab is more effective than Pembrolizumab
Bibliographic record
Abstract
Abstract Immune checkpoint blockade (ICB) has revolutionized the treatment of cancer. Present models show that anti-PD-1 operates simply by blocking co-receptor binding to its ligand PD-L1. Surprisingly, no previous studies have assessed whether ICB also induces the internalization or endocytosis of PD-1 from the cell surface. Many, but not all receptors, undergo endocytosis upon antibody or ligand binding. In this study, PD-1 internalization was assessed on activated human T cells by flow cytometry and fluorescence microscopy. Immunoprecipitation and western blotting were performed to assess the destiny of PD-1 after internalization. Our results report that anti-PD-1 induces the rapid internalization of PD-1 from the surface of T-cells in a manner comparable to CD28. A substantial minority of receptors were also resistant to antibody-induced endocytosis. Further, Nivolumab was considerably more effective than Pembrolizumab in inducing the endocytosis of PD-1 in primary human T-cells. This difference was the result of several factors where Nivolumab bound to a greater number of PD-1 molecules on the surface of T-cells than Pembrolizumab, indicating that the co-receptor might exist with different conformations on activated cells. Moreover, Nivolumab induced more rapid endocytosis (5.5 versus 3.6% per minute) and a greater percentage of PD-1 molecules than Pembrolizumab (70% versus 50%). The relative effect of anti-PD-1 molecules on internalization was seen equally on activated CD4 helper and CD8+ effector/memory T-cells. The internalization and the degradation of PD-1 were partially blocked by the inhibition of clathrin-mediated endocytosis and proteasome activity. Our studies show for the first time that ICB involves a second level of modulation involving the internalization of PD-1 from the surface of T-cells, an event which will contribute to the efficacy of ICB. Citation Format: Elham Ben Saad, Andres Oroya, Christopher E. Rudd. Anti-PD-1 induces the endocytosis of the co-receptor from the surface of T-cells: Nivolumab is more effective than Pembrolizumab [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6528.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".