TMN3 Antibody
Description
Overview of TIM-3
TIM-3 is a 60 kDa type I transmembrane glycoprotein belonging to the TIM family. It consists of:
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Extracellular domain (ECD): IgV-like domain and mucin stalk (181 amino acids in humans) .
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Cytoplasmic tail: 78 amino acids with conserved tyrosine phosphorylation motifs .
Key isoforms: A truncated splice variant lacks the cytoplasmic domain, potentially functioning as a soluble decoy receptor .
Functional Mechanisms
TIM-3 regulates immune responses by interacting with ligands:
Blocking TIM-3 enhances IFN-γ production, T-cell cytotoxicity, and anti-tumor immunity .
Key TIM-3 Antibodies in Development
Therapeutic antibodies targeting TIM-3 aim to disrupt ligand interactions and reverse T-cell exhaustion:
Clinical Relevance
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Cancer: TIM-3 is upregulated in PD-1-resistant tumors and correlates with poor prognosis in lung adenocarcinoma and melanoma .
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Autoimmunity: TIM-3 blockade exacerbates experimental autoimmune encephalomyelitis (EAE) in mice .
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Combination Therapy: Co-blockade of TIM-3 and PD-1/PD-L1 shows enhanced anti-tumor efficacy in preclinical models .
Challenges and Future Directions
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Ligand Redundancy: TIM-3 binds multiple ligands, necessitating antibodies that block all interfaces .
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Biomarker Development: No companion diagnostics are approved; research focuses on TIM-3/PD-1 co-expression as a predictive marker .
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Safety: Early-phase trials report acceptable toxicity, but long-term effects remain uncharacterized .
Product Specs
Target Background
Q&A
FAQs for TIM-3 Antibody Research (Academic Focus)
Note: "TMN3" is presumed to refer to TIM-3 (T-cell immunoglobulin and mucin-domain containing-3), an immune checkpoint target. Corrections are based on contextual analysis of provided sources.
What experimental models are appropriate for validating TIM-3 antibody efficacy in cancer immunotherapy?
TIM-3 antibodies require validation in models that replicate human immune-tumor interactions:
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Syngeneic mouse models (e.g., MC38 colorectal cancer) to study endogenous T-cell modulation .
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Humanized PBMC or CD34+ models for evaluating human-specific TIM-3 interactions .
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Ex vivo tumor-infiltrating lymphocyte (TIL) assays to assess functional reinvigoration of exhausted T-cells .
Key controls:
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Isotype-matched antibodies to rule out non-specific effects.
How do TIM-3 antibodies differ mechanistically from PD-1/PD-L1 inhibitors?
TIM-3 antibodies target distinct pathways in T-cell exhaustion:
| Feature | TIM-3 Antibodies | PD-1/PD-L1 Inhibitors |
|---|---|---|
| Primary mechanism | Blockade of galectin-9 interaction | Disruption of PD-1/PD-L1 binding |
| Co-expression | Often co-expressed with PD-1 on exhausted T-cells | Rarely co-expressed with TIM-3 |
| Tumor microenvironment impact | Reduces myeloid-derived suppressor cell recruitment | Primarily enhances cytotoxic T-cell activity |
Source: Preclinical data showing TIM-3's role in myeloid cell modulation .
How can conflicting TIM-3 expression data across cancer subtypes be resolved methodologically?
Discrepancies often arise from:
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Antibody validation: Use ≥2 clones (e.g., clone 344823 vs. R&D Systems F38-2E2) with orthogonal validation (flow cytometry, RNAscope) .
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Tumor heterogeneity: Multi-region sampling and single-cell RNA sequencing to account for spatial variability .
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Post-translational modifications: Glycosylation status of TIM-3 affects antibody binding; employ enzymatic pretreatment (neuraminidase) in IHC .
Example workflow:
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Validate antibodies using TIM-3-transfected cell lines vs. knockout controls.
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Correlate protein expression with RNA-seq data from TCGA.
What strategies optimize TIM-3 antibody engineering for enhanced Fc effector function?
Rational engineering approaches include:
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Fc domain modifications:
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Bispecific formats:
Critical parameters:
| Parameter | Consideration |
|---|---|
| Affinity | Maintain KD ≥1 nM to avoid T-cell overactivation |
| Cross-reactivity | Validate against primate TIM-3 orthologs |
| Solubility | Reduce hydrophobic patches in CDR-H3 regions |
Source: Structural insights from antibody-antigen co-crystallography .
How should researchers address TIM-3 antibody-dependent cytokine release syndromes (CRS) in preclinical studies?
Mitigation strategies include:
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Tuning FcγR binding: Use IgG4 isotype or LALA mutations to reduce monocyte activation .
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Dose escalation protocols: Start at 0.1 mg/kg in NHP studies, monitoring IL-6/IFN-γ levels .
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Temporal profiling: Single-cell RNA-seq of peripheral blood monocytes at 6/24/48h post-injection .
Data contradiction example:
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Some studies report CRS with IgG1 formats but not IgG4 . Resolution requires FcγRIIB binding assays and in vivo macrophage depletion experiments.
Methodological Tables
Table 1. Comparison of TIM-3 Antibody Validation Techniques
| Method | Sensitivity | Specificity Challenges | Recommended Use |
|---|---|---|---|
| Flow cytometry | High (≥1:1,000) | Cross-reactivity with TIM-1/TIM-4 | Primary screening |
| IHC (FFPE) | Moderate | Epitope masking by glycosylation | Spatial analysis in tumors |
| Surface plasmon resonance | Ultra-high | Requires purified TIM-3 ectodomain | Affinity/kinetic measurements |
Source: Antibody validation frameworks from structural studies .
