The invention relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of impaired synaptic plasticity. The invention also relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of toxicity of A oligomers. The invention also relates to a ligand capable of binding PrP at a site within amino acid residues 131 to 153 of PrP, for use in treatment or prevention of Alzheimer's Disease. The invention also relates to methods of medical treatment.

A monoclonal antibody against human PrPc protein capable of reducing the expression level of transcription factor Twist1 in a targeting mode and inducing macrophage and NK cells to target to rectal cancer tumor cells. The combined drug therapy with the antibody and cetuximab also exhibits inhibitory effect on tumor better than administration of the antibody or cetuximab alone.

The invention relates to diagnosis, prevention, and treatment of diseases and conditions associated with the functions of prion-like or Tetz-proteins.