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© 2022 Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ. This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See https://creativecommons.org/licenses/by/4.0/ . Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Background

Despite extensive clinical use, the mechanisms that lead to therapeutic resistance to anti-programmed cell-death (PD)-1 monoclonal antibodies (mAbs) remain elusive. Here, we sought to determine how interactions between the Fc region of anti-PD-1 mAbs and Fcγ receptors (FcγRs) affect therapeutic activity and how these are impacted by the immune environment.

Methods

Mouse and human anti-PD-1 mAbs with different Fc binding profiles were generated and characterized in vitro. The ability of these mAbs to elicit T-cell responses in vivo was first assessed in a vaccination setting using the model antigen ovalbumin. The antitumor activity of anti-PD-1 mAbs was investigated in the context of immune ‘hot’ MC38 versus ‘cold’ neuroblastoma tumor models, and flow cytometry performed to assess immune infiltration.

Results

Engagement of activating FcγRs by anti-PD-1 mAbs led to depletion of activated CD8 T cells in vitro and in vivo, abrogating therapeutic activity. Importantly, the extent of this Fc-mediated modulation was determined by the surrounding immune environment. Low FcγR-engaging mouse anti-PD-1 isotypes, which are frequently used as surrogates for human mAbs, were unable to expand ovalbumin-reactive CD8 T cells, in contrast to Fc-null mAbs. These results were recapitulated in mice expressing human FcγRs, in which clinically relevant hIgG4 anti-PD-1 led to reduced endogenous expansion of CD8 T cells compared with its engineered Fc-null counterpart. In the context of an immunologically ‘hot’ tumor however, both low-engaging and Fc-null mAbs induced long-term antitumor immunity in MC38-bearing mice. Finally, a similar anti-PD-1 isotype hierarchy was demonstrated in the less responsive ‘cold’ 9464D neuroblastoma model, where the most effective mAbs were able to delay tumor growth but could not induce long-term protection.

Conclusions

Our data collectively support a critical role for Fc:FcγR interactions in inhibiting immune responses to both mouse and human anti-PD-1 mAbs, and highlight the context-dependent effect that anti-PD-1 mAb isotypes can have on T-cell responses. We propose that engineering of Fc-null anti-PD-1 mAbs would prevent FcγR-mediated resistance in vivo and allow maximal T-cell stimulation independent of the immunological environment.

Details

Title
Fc-null anti-PD-1 monoclonal antibodies deliver optimal checkpoint blockade in diverse immune environments
Author
Moreno-Vicente, Julia 1   VIAFID ORCID Logo  ; Willoughby, Jane E 2   VIAFID ORCID Logo  ; Taylor, Martin C 2 ; Booth, Steven G 2 ; English, Vikki L 2 ; Williams, Emily L 2 ; Penfold, Christine A 2 ; Mockridge, C Ian 2 ; Inzhelevskaya, Tatyana 2 ; Kim, Jinny 2 ; Chan, H T Claude 2 ; Cragg, Mark S 2 ; Gray, Juliet C 2 ; Beers, Stephen A 2 

 Antibody and Vaccine Group, Centre for Cancer Immunology, Cancer Sciences, University of Southampton, Southampton, UK; Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK 
 Antibody and Vaccine Group, Centre for Cancer Immunology, Cancer Sciences, University of Southampton, Southampton, UK 
Section
Basic tumor immunology
Publication year
2022
Publication date
Jan 2022
Publisher
BMJ Publishing Group LTD
e-ISSN
20511426
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2618783210
Copyright
© 2022 Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ. This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See https://creativecommons.org/licenses/by/4.0/ . Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.