TIM-3 (HAVCR2) has emerged as one of the most biologically compelling and technically complex targets of the next generation of immune checkpoints. Unlike PD-1, TIM-3 is a multi-ligand receptor that spans T-cell exhaustion, myeloid cell regulation, and leukemic stem cell survival — creating multiple distinct therapeutic opportunities. MAbSilico engineers anti-TIM-3 candidates from 156 annotated antibodies, with precision targeting of the IgV cleft and multi-ligand blockade strategies.
TIM-3 possesses a multi-modal functional profile spanning T-cell exhaustion, myeloid regulation, and leukemic stem cell survival — unlike canonical binary-switch checkpoints like PD-1. Its structural complexity creates both engineering challenges and differentiated therapeutic opportunities.
TIM-3 is a Type I transmembrane glycoprotein encoded by the HAVCR2 gene at locus 5p33.3, encoding a 301 amino acid protein. Its extracellular portion consists of an N-terminal immunoglobulin variable (IgV) domain and a mucin-like stalk domain. The IgV domain features a unique antiparallel beta-sheet fold stabilized by four non-canonical cysteines and two disulfide bonds, forming a distinct cleft between the CC’ and FG loops — the key ligand-recognition interface.
Unlike PD-1 (which has ITIM and ITSM motifs), TIM-3 lacks classical immunoreceptor tyrosine-based inhibition motifs. Its cytoplasmic tail contains five conserved tyrosine residues (Y265 and Y272 in humans) that serve as docking sites for Src homology 2 (SH2) domains. Signaling is governed by Bat3 (HLA-B-associated transcript 3): in its inactive state, Bat3 binds TIM-3 and recruits Lck, maintaining T-cell receptor signaling. Upon ligand engagement, Bat3 dissociates — dampening TCR activation.
| Ligand | Molecular Source | Biological Outcome |
|---|---|---|
| Galectin-9 (Gal-9) | Immune and tumor cells | Induces Th1/CD8 apoptosis via calcium flux; mediates tolerance |
| Phosphatidylserine (PtdSer) | Apoptotic cells | Efferocytosis; stimulates NF-κB signaling |
| HMGB1 | Dying tumor cells | Competes with nucleic acids to suppress innate immune activation |
| CEACAM1 | Immune and tumor cells | Forms cis/trans heterodimers; essential for TIM-3 inhibitory function |
| LSECtin | Liver and TAMs | Inhibits antitumor T-cell responses in the liver microenvironment |
The TIM-3 field has largely converged on IgG4 for checkpoint blockade, balancing potent ligand blockade with avoidance of effector-cell depletion. The next wave pivots to bispecific formats combining TIM-3 with PD-1 blockade.
The IgG4 (S228P) subclass is preferred for TIM-3 checkpoint blockade because it avoids ADCC-mediated depletion of effector T cells or myeloid cells that constitutively express TIM-3. Sabatolimab (MBG453) uses humanized IgG4 (S228P) and, uniquely, also promotes ADCP of TIM-3⁺ leukemic stem cells (LSCs) via Fcγ engagement — leveraging TIM-3's expression on LSCs for the AML indication. Cobolimab (TSR-022) was humanized via SHM-XEL technology and uses IgG4 to avoid ADCC while maximizing T-cell checkpoint blockade.
Bispecific strategy: AZD7789 (sabestomig), targeting both PD-1 and TIM-3 simultaneously, represents the rational next step. TIM-3 is co-expressed with PD-1 on terminally exhausted T cells — dual blockade provides synergistic T-cell reactivation that neither agent achieves alone. LB1410, a bivalent PD-1×TIM-3 bispecific, is specifically designed to overcome acquired PD-1 resistance.
ADC approach: KK2845, a TIM-3-targeting ADC with cytotoxic payload delivery, is designed to directly eradicate TIM-3⁺ leukemic cells. This leverages TIM-3's role as a leukemic stem cell marker in AML for a fundamentally different therapeutic mechanism from checkpoint blockade.
Our 6-step workflow is optimized for TIM-3's unique challenge: blocking multiple distinct ligands simultaneously while preserving beneficial immune cell populations.
TIM-3's multi-ligand biology, LSC expression, and co-exhaustion with PD-1 create multiple differentiated therapeutic angles. MAbSilico navigates this complexity from 156 annotated sequences.