Abstract 2401: Developing a single B cell platform to accelerate antibody discovery and screening.

Abstract Rapid and efficient isolation of antigen-specific B cells is a critical bottleneck during antibody discovery, especially for antigens that are complex, maintain small and specific epitopes, or have a low immunogenicity. To solve this challenge, we developed a next-generation single B cell discovery platform focusing around utilizing both fluorescence-activated cell sorting(FACS) and CellCelector(CC) to maximize the recovery of low-population, high-value B cells. By performing an initial screen concurrently, this platform is able to maximize its complementary strengths: FACS with the deep sampling of large lymphocyte populations with precise multi-parametric gating, while CC can ensure a flexible, image-guided recovery of more fragile B cell subsets. This dual-mode workflow increases single-cell retrieval efficiency, reduces sampling bias, and improves downstream recombinant antibody expression success rates. To demonstrate platform performance, we employed a case study targeting DM1, a maytansinoid payload widely used in ADC development. Antigen-specific memory B cells were enriched and screened using fluorescent DM1 conjugates. FACS revealed a success rate of 73%, and after setting the gating parameters, 96 Abs with rIgGwith rIgG+/hIgG-DM1+/rIgM- binding was selected. Out of the 49 unique CDR3 Abs, 45 were specific to DM1 and first screened by ELISA. Antibodies with an affinity above nanomolar levels were further confirmed by biolayer interferometry (BLI) and ELISA, highlighting 19 potential candidates against DM1. Binding characterization revealed that 19 antibodies exhibited affinities above the nanomolar range, confirming robust recognition of the DM1 moiety. These results highlight the power of combining parallel FACS and CellCelector workflows to capture diverse, high-affinity antibody repertoires, even against complex small-molecule payloads. Overall, the platform provides a scalable, high-confidence route for antibody discovery supporting ADC payload targeting, mechanistic studies, and the development of next-generation biotherapeutics. Citation Format: Spencer Chiang, An Ouyang, Yu Sun, Xiaoli Li. Developing a single B cell platform to accelerate antibody discovery and screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2401.