Author:
Luong Michael,Wang Ying,Donnelly Brianna B.,Lepsy Christopher
Abstract
AbstractPF-07257876 is a bispecific antibody being developed for the treatment of certain advanced or metastatic solid tumors. To support clinical development of PF-07257876, neutralizing antibody (NAb) assays were developed as part of a tiered immunogenicity testing approach. Because PF-07257876 targets both CD47 and PD-L1, determination of domain specificity of a NAb response may provide additional insight relating to PK, efficacy, and safety. Due to limitations of functional cell systems, two cell-based binding assays were developed using electrochemiluminescence to detect domain-specific NAb. While both NAb assays utilized a cell-based binding approach and shared certain requirements, such as sensitivity and tolerance to potentially interfering substances, the development of each assay faced unique challenges. Among the hurdles encountered, achieving drug tolerance while preserving domain specificity for CD47 proved particularly challenging. Consequently, a sample pretreatment procedure to isolate NAb from potentially interfering substances was necessary. The sample pretreatment procedure developed was based on a bead-extraction and acid dissociation (BEAD) approach. However, the use of the standard BEAD approach with whole drug to capture NAb resulted in loss of NAb detection under certain circumstances. Specifically, mock samples containing a mixture of NAb positive controls against both binding domains of the bispecific antibody produced false-negative results in the cell-based binding assay. An adaptation made to the standard BEAD approach restored domain-specific NAb detection, while also contributing to an assay sensitivity of 1 µg/mL in the presence of a clinically relevant drug tolerance level of up to 400 µg/mL.
Graphical Abstract
Publisher
Springer Science and Business Media LLC
Reference12 articles.
1. Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et al. Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2021;71(3):209–49.
2. Chen SH, Dominik PK, Stanfield J, Ding S, Yang W, Kurd N, et al. Dual checkpoint blockade of CD47 and PD-L1 using an affinity-tuned bispecific antibody maximizes antitumor immunity. J Immunother Cancer. 2021;9:e003464. https://doi.org/10.1136/jitc-2021-003464
3. Bano N, McKelvey T, Spear N, Yang TY, Shankar G, Schantz A. Analysis of regulatory guidance on antidrug antibody testing for therapeutic protein products. Bioanalysis. 2019;11(24):2283–96.
4. Gorovits B, Wakshull E, Pillutla R, Xu Y, Manning MS, Goyal J. Recommendations for the characterization of immunogenicity response to multiple domain biotherapeutics. J Immunol Methods. 2014;408:1–12.
5. FDA. Immunogenicity testing of therapuetic protein products - developing and validating assays for anti-drug antibody detection - guidance for industry. https://www.fdagov/media/119788/download2019. Accessed 21 Aug 2023.