CD73 (NT5E, Ecto-5'-Nucleotidase) is an ectoenzyme that converts AMP to adenosine, completing the final step of extracellular ATP degradation. While adenosine generation is generally considered anti-inflammatory, dysregulated CD73 activity can lead to excessive immunosuppression and may contribute to neurodegenerative disease progression. CD73 inhibitors represent a nuanced approach to modulate purinergic signaling[1].
CD73 is encoded by the NT5E gene located on chromosome 6q14.1. Key features include:
| Property | Description |
|---|---|
| Enzyme Activity | Hydrolyzes AMP → Adenosine |
| Expression | Immune cells, endothelial cells, neurons, astrocytes |
| Function | Adenosine production, immune regulation |
| Location | Cell surface (GPI-anchored) |
| Molecular weight | ~70 kDa (dimer) |
CD73 works in concert with CD39 to generate adenosine from ATP. The balance between these enzymes determines the net purinergic signaling outcome[2].
CD73 inhibitors modulate adenosine levels and immune function through several mechanisms[3]:
Adenosine Modulation: CD73 inhibitors reduce excessive adenosine production, preventing over-immunosuppression that can impair pathogen clearance and tumor surveillance[1:1].
Immune Balance: By preventing excessive immunosuppression, CD73 inhibitors may restore immune surveillance.
Combination Potential: CD73 inhibitors may be combined with CD39 inhibitors for complete purinergic modulation.
Context-Dependent Effects: The benefit of CD73 inhibition depends on disease context; in some neurodegenerative contexts, adenosine may be protective.
Adenosine acts through four receptor subtypes (A1, A2A, A2B, A3), each with distinct effects:
| Receptor | Location | Effect | Neurodegeneration Relevance |
|---|---|---|---|
| A1R | Neurons, glia | Inhibitory (Gi) | Neuroprotective, anti-excitotoxic |
| A2AR | Striatum, immune cells | stimulatory (Gs) | Pro-inflammatory when overactive |
| A2BR | Low expression | Various | Less characterized |
| A3R | Low expression | Various | Potential pro-apoptotic |
CD73 inhibitors may benefit in specific contexts[4]:
CD73 modulation may be relevant[5]:
CD73 inhibitors are primarily in oncology, with limited neuroscience applications:
| Compound | Company | Development Stage | Notes |
|---|---|---|---|
| AB680 | Arcus Biosciences | Phase 1 (oncology) | Potent CD73 inhibitor |
| MEDI9447 (Oleclumab) | AstraZeneca | Phase 2 (oncology) | Monoclonal antibody |
| CPI-006 | Corvus Pharmaceuticals | Phase 1 (oncology) | CD73 antagonist |
| JAB-630 | Jacobio Pharmaceuticals | Phase 1 (oncology) | Small molecule |
| Compound | Type | Notes |
|---|---|---|
| APCP | Nucleotide analog | Classic CD73 inhibitor |
| PSB-12379 | Small molecule | High selectivity |
| TH287 | Small molecule | In vivo activity |
Allard B, et al. CD73: a potent immunosuppressor and tumor promoter. Cancer Res. 2018. ↩︎ ↩︎
Zabel M, et al. CD73-derived adenosine in autoimmune and neurodegenerative disease. Nat Rev Immunol. 2019. ↩︎
Hyun K, et al. CD73 inhibition as a therapeutic strategy in neuroinflammation. J Neuroinflammation. 2020. ↩︎
Blay J, et al. Purinergic signaling in neuroinflammation and dementia. Pharmacol Rev. 2021. ↩︎
Cevera E, et al. CD73-adenosinergic pathway in Parkinson's disease models. Neurobiol Dis. 2022. ↩︎