Cyclic tetrapeptides and therapeutic applications thereof

A method of treating an immune-mediated disease selected from psoriasis and dermatitis, comprising administering to a patient in need thereof an efficacious amount of a compound of formula I:

• wherein
• k, m, n and p are each independently 0, 1 or 2, provided that at least one of k, m, n and p is not zero;
• R is selected from H and C1-3 alkyl and R′ is selected from H and optionally substituted C1-3 alkyl, or, when taken together, R and R′, together with the peptide backbone atoms to which they are attached, form an optionally substituted 5- or 6-membered ring or an optionally substituted 9- or 10-membered bicyclic ring, said 5- or 6-membered ring or said 9- or 10-membered bicyclic ring being saturated or unsaturated;
• R″ is selected from H and C1-3 alkyl and R′″ is selected from H and optionally substituted C1-3 alkyl, or, when taken together, R″ and R′″, together with the peptide backbone atoms to which they are attached, form an optionally substituted 5- or 6-membered ring or an optionally substituted 9- or 10-membered bicyclic ring, said 5- or 6-membered ring or said 9- or 10-membered bicyclic ring being saturated or unsaturated;
• R7 and R8 are each H;
• and
• R3 and R4 are each independently selected from aryl(Cyalkyl), substituted aryl(Cyalkyl), heteroaryl(Cyalkyl) and substituted heteroaryl(Cyalkyl), wherein y is 0, 1 or 2;
• or R3 may be taken together with R7 and the intervening carbon and nitrogen atoms to form a 5- or 6-membered ring or a 9- or 10-membered cyclic ring, which 5- or 6-membered ring or a 9- or 10-membered bicyclic ring may contain unsaturation, and R4 may taken together with R8 and the intervening carbon and nitrogen atoms to form a 5- or 6-membered ring or a 9- or 10-membered bicyclic ring, which 5- or 6-membered ring or a 9- or 10-membered bicyclic ring may be contain unsaturation;
• or a pharmaceutically acceptable salt thereof.