Mitchell Ho, Ph.D.

Dr. Ho’s laboratory studies cell-surface biology and immune recognition and translates these discoveries into new medicines for cancer. We are an interdisciplinary team of scientists that integrate cancer biology, protein biochemistry, antibody engineering, and cellular immunotherapy to understand how cell-surface molecules regulate signaling in cancer and how these mechanisms can be exploited therapeutically.

A major focus of the laboratory is the glypican family of cell-surface heparan sulfate proteoglycans, particularly GPC1, GPC2, and GPC3. Through studies spanning molecular mechanism, protein biology, antibody discovery, and therapeutic engineering, the laboratory has helped establish glypicans as important regulators of cancer signaling and as a new class of therapeutic targets. These discoveries have led to antibodies, immunotoxins, antibody–drug conjugates, T-cell engagers, and engineered T-cell therapies for liver cancer, pancreatic cancer, neuroblastoma, and other solid tumors, with several advancing to clinical investigation.

The laboratory also develops technologies for protein discovery and engineering, including mammalian cell display, shark and camel nanobody libraries, antibody and nanobody humanization, and engineered immune receptors.

Establishing Glypicans as Cancer Therapeutic Targets

A fundamental challenge in treating solid tumors is the scarcity of cell-surface molecules that distinguish malignant cells from essential normal tissues. Our laboratory pioneered the study of glypicans as cancer-associated therapeutic targets and established biological and therapeutic roles for GPC1, GPC2, and GPC3.

Our work on GPC3, an oncofetal protein highly expressed in hepatocellular carcinoma and largely absent from normal adult tissues, established a mechanistic connection between glypicans and oncogenic signaling. We demonstrated that GPC3 functions as a Wnt co-receptor, identified functional Wnt-binding sites within GPC3, and developed antibodies, including HN3 and HS20, that helped define its role in regulating Wnt/β-catenin signaling. We subsequently uncovered a role for GPC3 in YAP signaling and identified FAT1 and alpha-fetoprotein (AFP) as GPC3-associated proteins, revealing new connections between cell-surface proteoglycans and cancer signaling.

We extended these discoveries across the glypican family. We were among the first to identify GPC2 as a therapeutic target in pediatric cancers, particularly neuroblastoma, and demonstrated tumor suppression with GPC2-directed CAR T cells and immunotoxins. We also established GPC1 as a candidate therapeutic target in pancreatic cancer, demonstrated its role in Wnt signaling, and developed GPC1-targeted D4 nanobody immunotoxins and CAR T cells.

Our studies of mesothelin, another important solid-tumor antigen, identified its functional binding site for MUC16/CA125 and helped establish a molecular framework for understanding mesothelin biology and developing mesothelin-directed therapies.

Engineering Antibodies and T Cells for Cancer

Our laboratory translates discoveries in tumor biology into antibody- and T-cell-based therapies while seeking to define fundamental principles connecting antigen biology, epitope geometry, receptor architecture, and immune-cell function.

For GPC3, we developed antibodies including HN3 and YP7 and used them to construct immunotoxins, antibody–drug conjugates, T-cell engagers, and CAR T cells. Humanized YP7-derived CAR T cells demonstrated potent and durable activity in preclinical liver cancer models and advanced to clinical investigation at the NIH in collaboration with Tim Greten (NCI).

In neuroblastoma, we identified cancer-associated regions of GPC2 and developed the CT3 monoclonal antibody and CT3-derived CAR T cells. By integrating tumor RNA sequencing with antibody discovery, this work identified therapeutically actionable epitopes and provided a foundation for GPC2-directed immunotherapies. CT3-derived CAR T cells have advanced to clinical investigation at the NIH in collaboration with Rosa Nguyen (NCI).

For mesothelin-expressing cancers, we developed YP218, a rabbit monoclonal antibody that recognizes a rare membrane-proximal epitope. Humanized YP218-derived CAR T cells demonstrated strong antitumor activity and progressed toward clinical evaluation at the NIH for mesothelioma and other solid tumors in collaboration with Raffit Hassan (NCI).

We also investigate the molecular principles governing engineered T-cell function. Using B7-H3-targeting nanobodies such as B12, we demonstrated that CAR epitope location can profoundly influence T-cell signaling, tumor infiltration, and antitumor activity. Studies of GPC1- and GPC3-directed nanobody CARs further revealed how receptor architecture and dimerization regulate T-cell activity, establishing design principles for targeting tumors with low antigen density.

To address tumor antigen heterogeneity, we collaborated with Eureka Therapeutics to develop antibody–T-cell receptor (AbTCR) T cells, which combine antibody-based tumor recognition with γδ T-cell receptor signaling. These cells demonstrated activity against tumors with low antigen expression, providing an alternative strategy for engineered T-cell therapy in solid tumors, and progressed toward clinical investigation at the NIH.

Developing Antibody and Protein Engineering Technologies

Our laboratory develops technologies that expand the molecular repertoire available for biological discovery and therapeutic engineering.

Dr. Ho first described mammalian cell display for the expression and selection of antibodies directly on mammalian cells, establishing a versatile platform for antibody discovery and engineering. Our laboratory recently began collaborating with Fusion Antibodies to develop full-length human IgG libraries and screening strategies using mammalian cell display.

Our laboratory developed large nurse shark VNAR and dromedary camel VHH phage-display libraries, as well as the PCR-Extension Assembly and Self-Ligation (EASeL) method for library construction, in collaboration with Martin Flajnik at the University of Maryland. These platforms have yielded high-affinity single-domain antibodies against cancer and infectious-disease targets without animal immunization and provided compact recognition domains for CAR T cells, multispecific and multifunctional molecules, and other therapeutic proteins. Beyond cancer, we have used these libraries to discover neutralizing molecules against emerging pathogens, including SARS-CoV-2 and Lassa virus. Structural and functional studies have revealed how camel and shark single-domain antibodies can access epitopes that are difficult to target with conventional antibodies, supporting their development as versatile platforms for cancer and infectious diseases.

We have established hybrid computational and experimental protein-engineering strategies for humanizing antibodies and nanobodies derived from rabbits, mice, camels, and sharks. These approaches have produced therapeutically active molecules, including humanized YP218, YP7, and CT3, and provide a general framework for converting antibodies and nanobodies from diverse species into candidates suitable for therapeutic development.

We develop physiologically relevant three-dimensional tumor spheroid models to investigate therapeutic resistance and uncover vulnerabilities that may be missed in conventional two-dimensional cultures, in collaboration with Shuichi Takayama at the University of Michigan and V. Courtney Broaddus at UCSF.

Teaching Interests

BIOC301/302 - Biochemistry I/II

Dr. Mitchell Ho received his Ph.D. from the University of Illinois at Urbana-Champaign as a National Research Service Award Predoctoral Fellow. He subsequently joined the National Cancer Institute (NCI) as a postdoctoral fellow with Dr. Ira Pastan and was appointed a tenure-track Investigator in 2008. He was promoted to Senior Investigator with tenure in 2015 and currently serves as Deputy Chief of the Laboratory of Molecular Biology and Director of the Antibody Engineering Program at NCI.

Dr. Ho is internationally recognized for his pioneering contributions to antibody engineering and cancer therapeutics, particularly his work establishing glypicans as therapeutic targets and advancing single-domain antibodies for protein- and cell-based therapies. He is the founding Editor-in-Chief of Antibody Therapeutics (Oxford University Press) and serves on the boards of directors of the Antibody Society and the Foundation for Advanced Education in the Sciences. His honors include the APAO Scientific Achievement Award and the HHS Dr. Francisco S. Sy Award for Mentorship Excellence. He was elected a Fellow of the American Institute for Medical and Biological Engineering (AIMBE) in 2023 and was named Asian American Engineer of the Year in 2024.