Method for treatment of an IL-17A-mediated disease through antibody administration specific to human IL-17A

A method for treatment of an IL-17A-mediated disease or disorder, comprising administering to a patient in need thereof an antibody or a fragment thereof that specifically binds to human IL-17A and comprises a heavy chain variable domain VHH, and a light chain variable domain VL comprising the amino acid sequence of SEQ ID NO:

• 8, wherein the VHH comprises:
• a) HCDR1, HCDR2 and HCDR3 comprising the amino acid sequences of SEQ ID NO:
• 4, SEQ ID NO:
• 5 and SEQ ID NO:
• 6, respectively;
• or
• b) a variant of a), comprising one amino acid substitution selected from the group consisting of:
• the amino acid at the 6th position of SEQ ID NO:
• 4 is N, K, R, E, W, M, Q, D, F, V, L or A;
• the amino acid at the 7th position of SEQ ID NO:
• 4 is S;
• the amino acid at the 8th position of SEQ ID NO:
• 4 is I;
• the amino acid at the 9th position of SEQ ID NO:
• 4 is L, A, I, S, R, V, N, Q or M;
• the amino acid at the 1st position of SEQ ID NO:
• 5 is G or L;
• the amino acid at the 4th position of SEQ ID NO:
• 5 is A;
• the amino acid at the 7th position of SEQ ID NO:
• 5 is S, R, P, D, I, T, E, K, A, Lor W;
• the amino acid at the 3rd position of SEQ ID NO:
• 6 is K, S, A, T, D or G;
• the amino acid at the 4th position of SEQ ID NO:
• 6 is K;
• the amino acid at the 5th position of SEQ ID NO:
• 6 is G, Y, H, D, W or K;
• the amino acid at the 6th position of SEQ ID NO:
• 6 is A, V, S, L M or H;
• the amino acid at the 8th position of SEQ ID NO:
• 6 is E, G, A, R, V, K or Q;
• the amino acid at the 9th position of SEQ ID NO:
• 6 is S or N;
• the amino acid at the 10th position of SEQ ID NO:
• 6 is G, S, P, V, R, N or K;
• the amino acid at the 11th position of SEQ ID NO:
• 6 is V, M, C, T, L, Y, A, H, G or I;
• the amino acid at the 12th position of SEQ ID NO:
• 6 is W or S;
• the amino acid at the 13th position of SEQ ID NO:
• 6 is R, V, L, A, W, K, G, Q or I;
• the amino acid at the 14th position of SEQ ID NO:
• 6 is L, A or S;
• and
• the amino acid at the 15th position of SEQ ID NO:
• 6 is T, L, P, N, A, Q, F, I or D.