Penpulimab, an Fc-Engineered IgG1 Anti-PD-1 Antibody, With Improved Efficacy and Low Incidence of Immune-Related Adverse Events

Abstract

BackgroundIgG4 anbibodies are deficient in stability and may contribute to tumor-associated escape from immune surveillance. We developed an IgG1 backbone anti-programmed cell death protein-1 (PD-1) antibody, penpulimab, which is designed to remove crystallizable fragment (Fc) gamma receptor (FcγR) binding that mediates antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and proinflammatory cytokine release.MethodsAggregation of different anti-PD-1 antibodies was tested by size exclusion chromatography, and melting temperature midpoint (Tm) and aggregation temperature onset (Tagg) were also determined. The affinity constants of penpulimab for PD-1 and human FcγRs were measured by surface plasmon resonance and biolayer interferometry. ADCC and ADCP were determined in cellular assays and antibody-dependent cytokine release (ADCR) from human macrophages was detected by ELISA. Binding kinetics of penpulimab to human PD-1 was determined by Biacore, and epitope/paratope mapping of PD-1/penpulimab was investigated using x-ray crystallography. Additionally, patients from six ongoing trials were included for analysis of immune-related adverse events (irAEs).ResultsPenpulimab demonstrated better stability and a lower level of host-cell protein residue compared with IgG4 backbone anti-PD-1 antibodies. As expected, penpulimab exhibited no apparent binding to FcγRIa, FcγRIIa_H131, FcγRIIIa_V158 and FcγRIIIa_F158, elicited no apparent ADCC and ADCP activities, and induced no remarkable IL-6 and IL-8 release by activated macrophages in vitro. Penpulimab was shown in the co-crystal study to bind to human PD-1 N-glycosylation site at N58 and had a slower off-rate from PD-1 versus nivolumab or pembrolizumab. Four hundred sixty-five patients were analyzed for irAEs. Fifteen (3.2%) patients had grade 3 or above irAEs. No death from irAEs was reported.ConclusionsIgG1 backbone anti-PD1 antibody penpulimab has a good stability and reduced host cell protein residue, as well as potent binding to the antigen. Fc engineering has eliminated Fc-mediated effector functions of penpulimab including ADCC, ADCP and reduced ADCR, which may contribute to its more favorable safety profile.Clinical Trial Registrationwww.ClinicalTrials.gov, identifier: AK105-101: NCT03352531, AK105-201: NCT03722147, AK105-301: NCT03866980, AK105-202:NCT03866967, AK105-203: NCT04172571, AK105-204: NCT04172506.

Antibodies to watch in 2023

“…Penpulimab has demonstrated a slower antigen binding off rate compared with current marketed PD-1 antibodies that resulting in higher receptor occupancy that may improve antitumor activity. 98 Akesobio and Chia Tai-Tianqin Pharmaceutical Group Co, Ltd, a subsidiary of Sino Biopharmaceutical Limited, are developing penpulimab as a treatment for various tumor types. In 2021, the NMPA granted penpulimab its first approval, for treatment of patients with relapsed or refractory classic Hodgkin’s lymphoma after at least second-line systemic chemotherapy treatment in China.…”

B7 family protein glycosylation: Promising novel targets in tumor treatment

“…Highly N-glycosylated PD-1 is widely expressed in T cells and is the key to maintaining the stability and cell surface localization of PD-1 protein, especially the glycosylation at the N58 site, which is necessary to mediate its interaction with PD-L1 ( 16 , 108 ). Monoclonal antibodies STM418 ( 108 ), camrelizumab ( 17 ), mAb059c ( 109 ) and penpulimab ( 110 ) specifically target glycosylated PD-1 and have a high binding affinity for PD-1, effectively inhibiting PD-L1/PD-1 binding and enhancing anti-tumor immunity. In addition, adenine base editor (ABE) induces the conversion from a-t to g-c at specific sites, changes the coding sequence of the N74 residue of PDCD1 in CAR-T cells, downregulates the expression and glycosylation of PD-1 in CAR-T cells, and enhances the cytotoxicity in vitro and in vivo ( 111 ).…”

Finding the Right Heavy Chains for Immunostimulatory Antibodies

“…Silent IgG1 are either obtained by producing an aglycosylated variant through mutation in the N297 glycosylation site (G1e8, G1e11, G1e18), or by mutating critical residues in the FcγR interaction site of IgG, notably L234 and L235 (G1e9, G1e10, G1e15). In fact, unanimously, all the marketed anti-PD-1 antibodies are devoid of effector functions, being either IgG4 (pembrolizumab, nivolumab, cemiplimab, dostarlimab, tislelizumab, toripalimab and sintilimab) or silent IgG1 (penpulimab, as well as budigalimab and prolgolimab that are in clinical development) [ 29 , 30 ]. The anti-PD-1 pidilizumab (IgG1κ, G1e0) never passed the phase 2, not necessarily because it had not been Fc region silenced but more probably due to a restricted reactivity to certain PD-1 glycoforms and cross-reactivity with DLL-1 (delta-like canonical Notch ligand 1).…”