Does Letybo Contain Accessory Proteins?
There appears to be a critical error in your question: Letybo is not tocilizumab. Letybo is a botulinum toxin type A product, while tocilizumab (marketed as Actemra/RoActemra) is an IL-6 receptor antagonist monoclonal antibody. These are completely different medications with different structures, mechanisms, and clinical uses.
If You Are Asking About Tocilizumab (Not Letybo):
Tocilizumab does NOT contain "accessory proteins" in the traditional sense—it IS a protein therapeutic itself, specifically a recombinant humanized monoclonal antibody. 1
Molecular Structure of Tocilizumab
Tocilizumab is a recombinant humanized anti-human IL-6 receptor monoclonal antibody of the immunoglobulin IgG1κ (gamma 1, kappa) subclass with a typical H2L2 polypeptide structure. 1
Each light chain consists of 214 amino acids and each heavy chain consists of 448 amino acids. 1
The four polypeptide chains are linked intra- and inter-molecularly by disulfide bonds, with a molecular weight of approximately 148 kDa. 1
The antibody is produced in mammalian (Chinese hamster ovary) cells. 1
Formulation Components (Not "Accessory Proteins")
The FDA-approved formulations contain excipients (inactive ingredients) but no additional therapeutic proteins: 1
Intravenous formulation contains:
- Histidine (0.74 mg/mL)
- L-histidine hydrochloride monohydrate (1.09 mg/mL)
- Methionine (8.95 mg/mL)
- Polysorbate 80 (0.5 mg/mL)
- Threonine (19.06 mg/mL)
- Water for Injection, USP 1
Subcutaneous formulation contains:
- Histidine (0.7 mg per 0.9 mL)
- L-histidine hydrochloride monohydrate (1.0 mg per 0.9 mL)
- Methionine (8.1 mg per 0.9 mL)
- Polysorbate 80 (0.2 mg per 0.9 mL)
- Threonine (17.2 mg per 0.9 mL)
- Water for Injection, USP 1
Important Clarification
None of these excipients are "accessory proteins"—they are small molecules, amino acids, or surfactants used for stabilization and buffering. The only protein in tocilizumab formulations is tocilizumab itself. 1
If You Meant to Ask About Letybo (Botulinum Toxin):
You would need to consult the specific prescribing information for Letybo, as the evidence provided here pertains exclusively to tocilizumab and is not applicable to botulinum toxin products.