Research
Research Topics in Jung’s Lab
Based on in-depth knowledge of protein science and protein evolution principles, we delve deeply into the interactions among key proteins (antibodies, receptors, soluble ligands) within the human immune system to enhance our understanding of human immunology. We integrate this knowledge with engineering principles to devise cutting-edge immunotherapeutics.
In the long term, we are committed to propelling research on highly challenging and groundbreaking topics within the realm of antibody and protein engineering, focused on:
Revolutionized Discovery System: Pioneering in vitro immunization approaches that go beyond traditional animal/human immunization and pre-immune naïve antibody library screenings, markedly improving the efficiency of antibody discovery.
Pushing the Boundaries of Target Antigens: Developing antibodies against previously undruggable targets, including complex ion channels, intracellular antigens, and antigens associated with brain diseases.
Breakthrough Advances in Serum Persistence: Offering therapeutic antibodies with significantly reduced administration frequency/dosage and effective prophylactic antibodies to combat emerging infectious diseases.
Exceptional Therapeutic Potency: Achieving innovative treatments through multi-specific antibodies, small-sized non-antibody proteins, or conjugation/combination with other therapeutic agents such as small molecules, biomaterials, and cell therapeutics.
In the short to medium term, we aim to amplify the research momentum, driven by the launch of the following projects detailed below.
Project 1. Discovery of Antibodies for Diverse Target Antigens and Their Broad Applications
Over the past decade, our group has constructed several human antibody libraries with a size of over 1011, focusing on preserving innate antibody characteristics and ensuring vast diversity [1].
We have optimized various antibody display systems, ranging from phage to mammalian cell displays, to enhance the screening process [2-4].
Additionally, we have established methods to isolate antibodies from human-immunized antibody libraries and animal-immunized antibody libraries, enriched with clones that demonstrate high affinity and specificity for particular pathogens or vaccines [5].
Our goal is to leverage these advanced antibody discovery platforms to develop a broad spectrum of antibody therapeutics against various pathogenic antigens. These antigens include those associated with cancer, autoimmune disorders, and infectious diseases (Figure 1).
A significant focus will be on G-protein-coupled receptors (GPCRs) and ion channels, challenging targets for antibody development due to their complex conformations within the cell membrane, limited extracellular epitopes, and flexibility [1, 6, 7].
Additionally, in collaboration with excellent researchers from academia or biopharmaceutical industry, we are prepared to transform the antibodies we have discovered into innovative core materials for diverse applications, including cellular therapies, diagnostics, and biochemical research.
Figure 1. Antibody discovery platforms established in my laboratory for regulating the functions of diverse pathogenic antigens.
Project 2. Innovations in Antibody Discovery: Single B Cell Sorting and Native Genetic Pairing in IgG Chains
Although hybridoma technology has advanced monoclonal antibody production, it is constrained by screening efficiency and time-consuming procedures.
Combinatorial display platforms accelerate the screening process but fail to preserve the native genetic pairing between the heavy chain and the light chain of IgG, leading to complex screenings and extensive antibody engineering.
We aim to overcome these challenges by developing a technology to sort centrocytes from germinal center (GC) B cells. In the GC, centrocytes display hypermutated IgGs with high affinity and selectivity to particular antigens, a characteristic attributed to interactions with follicular dendritic cells and T follicular helper cells (Tfh), while maintaining the native IgG heavy and light chain pairing [8] (Figure 2A).
As an alternative approach, we plan to enhance antibody discovery while preserving the native IgG heavy and light chain pairing by co-encapsulating plasma cells with oligo d(T) beads using microfluidics and capturing antibody mRNA for in-droplet RT-PCR. This method will facilitate the construction of a yeast display library for efficient screening (Figure 2C) and accelerate the development of potent antibodies.
Figure 2. Antibody discovery via single B cell screening. (A) B cell maturation. (B) Flow cytometric sorting of IgG-bound centrocytes. (C) IgG H- and L-chain pairing via microfluidic encapsulation.
Project 3. Antibody Engineering and Applied Immunology Research Using the Palette of Fc Variants
The Fc region of IgG antibodies plays a crucial role in tumor cell clearance through mechanisms such as antibody-dependent cellular cytotoxicity (ADCC) (Figure 3A), antibody-dependent cellular phagocytosis (ADCP) (Figure 3B), antibody-dependent cellular trogocytosis (ADCT) (Figure 3C), and complement-dependent cytotoxicity (CDC) (Figure 3D) [9-11].
Recently, our group has identified cutting-edge Fc variants that outperform those from leading pharmaceutical companies (Figure 3A–3D).
We have also discovered effector function-silenced Fc variants suitable for antibodies targeting antigens on normal or immune cells (Figure 3E), as well as Fc variants that prolong the serum half-life of antibodies and Fc-fusion proteins (Figure 3F) [12, 13].
With our extensive array of Fc variants designed for diverse immunological roles, we envision combining these unique Fc mutations, much like an artist blends colors, to design antibodies with specific therapeutic functions. Leveraging our 'palette' of Fc variants (Figure 3G), we aim to craft antibody therapeutics with tailored efficacy, minimized side effects, and extended serum half-life.
Figure 3. Fc engineering achievements from my laboratory: (A–D) Enhanced effector functions (ADCC, ADCP, ADCT, CDC); (E) effector function silencing; (F) prolonged serum half-life; and (G) Utilizing the palette of Fc variants for versatile combinations.
Project 4. Development of Neutrophil-Engaging Bispecific Antibodies for Enhanced Tumor Cell Killing
Most therapeutic antibodies belong to the IgG class and elicit tumor cell killing potency through interacting with the FcγRIII receptor on NK cells. The challenge arises from the limited population of NK cells, which constitute only 1–3% of leukocytes.
In contrast, neutrophils constitute 70% of leukocytes and demonstrate enhanced antitumor potency when activated by IgA antibodies binding to their FcαR [14]. The use of IgA is limited, however, by its heavy glycosylation, instability, and a short 5–6 days half-life, compared to IgG's approximately 21 days.
To overcome these limitations, we will develop an IgG-based bispecific antibody that activates neutrophils through human FcαR binding, aiming to combine the strengths of both IgG and IgA while minimizing their weaknesses.
We plan to isolate and engineer a FcαR-specific human antibody to be incorporated into a bispecific format, targeting both tumor-associated antigens and FcαR. The antitumor efficacy of this innovative bispecific antibody will be evaluated using human immune cells (Figure 4).
Our goal is to pioneer an advanced strategy in antibody therapeutics, seeking superior antitumor efficacy beyond the current capabilities of existing antibody treatments.
Figure 4. Strategy for developing bispecific antibody platform Technology to activate neutrophils.
Project 5. Engineering Small-Sized Immune Checkpoint Proteins for Next-Generation Immunotherapy
Immune checkpoint proteins on immune cells play a pivotal role in regulating activation but can be exploited by cancer cells to evade immune surveillance.
Based on this mechanism, several treatments have been developed targeting proteins such as CTLA-4, PD-1, PD-L1, and LAG-3, leading to clinical use of ten FDA-approved antibody therapies. Despite their efficacy against a range of cancers, achieving consistent patient response rates remains a challenge.
Our team is making strides in the development of small immune checkpoint proteins to modulate immune cells and enhance tumor targeting, with a significant achievement in improving the affinity of PD-1 ectodomain for PD-L1 [15].
We are currently concentrating on the innovation of PD-L1, ICOS-L, B7-H6, and SIRP-α variants to boost immune responses, aiming to broaden their applications in monotherapies, combination treatments, and diagnostic imaging (Figure 5).
Figure 5. Regulation of T cells, NK cells, and macrophages activity by engineered immune checkpoint proteins.
References
Ju, M.S. et al. (2021) A human antibody against human endothelin receptor type A that exhibits antitumor potency. Exp Mol Med 53 (9), 1437-1448. (교신저자)
Jo, M. et al. (2018) Escherichia coli inner membrane display system for high-throughput screening of dimeric proteins. Biotechnol Bioeng 115 (12), 2849-2858. (교신저자)
Jung, S.T. et al. (2010) Aglycosylated IgG variants expressed in bacteria that selectively bind FcgammaRI potentiate tumor cell killing by monocyte-dendritic cells. Proc Natl Acad Sci USA 107 (2), 604-9. (제1저자)
Jung, S.T. et al. (2013) Effective phagocytosis of low Her2 tumor cell lines with engineered, aglycosylated IgG displaying high FcgammaRIIa affinity and selectivity. ACS Chem Biol 8 (2), 368-75. (제1저자)
Kim, W.S. et al. (2023) Isolation and characterization of single domain antibodies from banded houndshark (Triakis scyllium) targeting SARS-CoV-2 spike RBD protein. Fish Shellfish Immunol 138, 108807. (교신저자)
Jo, M. and Jung, S.T. (2016) Engineering therapeutic antibodies targeting G-protein-coupled receptors. Exp Mol Med 48 (2), e207. (교신저자)
Ju, M.S. and Jung, S.T. (2020) Antigen design for successful isolation of highly challenging therapeutic anti-GPCR antibodies. Int J Mol Sci 21 (21). (교신저자)
Klein, U. and Dalla-Favera, R. (2008) Germinal centres: role in B-cell physiology and malignancy. Nat Rev Immunol 8 (1), 22- 33.
Park, H.I. et al. (2016) The highly evolvable antibody Fc domain. Trends Biotechnol 34 (11), 895-908. (교신저자)
Lee, W. et al. (2023) Unlocking the power of complement-dependent cytotoxicity: engineering strategies for the development of potent therapeutic antibodies for cancer treatments. BioDrugs. (교신저자)
Kang, T.H. and Jung, S.T. (2020) Reprogramming the constant region of immunoglobulin G subclasses for enhanced therapeutic potency against cancer. Biomolecules 10 (3). (교신저자)
Ko, S. et al. (2022) An Fc variant with two mutations confers prolonged serum half-life and enhanced effector functions on IgG antibodies. Exp Mol Med 54 (11), 1850-1861. (교신저자)
Ko, S. et al. (2021) Recent achievements and challenges in prolonging the serum half-lives of therapeutic IgG antibodies through Fc engineering. BioDrugs 35 (2), 147-157. (교신저자)
Lohse, S. et al. (2016) An anti-EGFR IgA that displays improved pharmacokinetics and myeloid effector cell engagement in vivo. Cancer Res 76 (2), 403-417.
Ha, J.Y. et al. (2023) Glycan-controlled human PD-1 variants displaying broad-spectrum high binding to PD-1 ligands potentiate T cell. Mol Pharm 20 (4), 2170-2180. (교신저자)