A compound of formula: wherein R 1 represents H, Me, Et, CH=CH 2, C≡C-H or C≡C-Me; R 2 represents H, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 3 -C 8 cycloalkyl, -CH 2 -(C 3 -C 8 cycloalkyl), halogen or cyano; R 3 represents (i) or (ii) or (iii) Q represents a heteroatom selected from O, N and S and if N may optionally be substituted with C 1-4 alkyl; Z represents CO or SO 2; Y 1 represents (CH 2) n and, except when n represents 0, may optionally be substituted by Me; X 1 represents (CH 2) m and, except when m represents 0, may optionally be substituted by Me; n and m independently represent 0, 1, 2, 3, 4 or 5; Y 2 represents (CH 2) s and may optionally be substituted by Me; s represents 2, 3, 4, 5 or 6; Y 3 represents (CH 2) t and may optionally be substituted by Me; X 2 represents (CH 2) v and may optionally be substituted by Me; t and v independently represent 2 or 3 save that t + v = 4 or 5; R 4 represents H, OH, NR 6 R 7 or an aliphatic 4-8 membered heterocycle containing one or more heteroatoms selected from O, N and S, save that when R 4 is OH or NR 6 R 7, m is 2, 3, 4 or 5; R 5 represents H, OH, NR 8 R 9 or aliphatic 4-8 membered heterocycle containing one or more heteroatoms selected from O, N and S save that when R 5 is OH or NR 8 R 9, n is 2, 3, 4 or 5; in which the aliphatic heterocycle groups that R 4 and R 5 may represent may optionally contain a carbonyl or sulphone group and may optionally be substituted by one or more groups selected from -C 1 -C 4 alkyl, C 1 -C 4 hydroxyalkyl-, C 1 -C 4 alkoxy(C 1 -C 4)alkyl-, -C 1 -C 4 alkyleneCONR 10 R 11, CN, OH and NR 12 R 13; R 6, R 7, R 8, R 9 independently represent H, or C 1 -C 4 alkyl optionally substituted by OH, oxo, NR 14 R 15 or-C 1 -C 4 alkoxy; and R 10, R 11, R 12, R 13, R 14 and R 15 independently represent H or C 1 -C 4 alkyl; or a pharmaceutically acceptable salt thereof. R 1 represents H, Me, Et, CH=CH 2, C≡C-H or C≡C-Me; R 2 represents H, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 3 -C 8 cycloalkyl, -CH 2 -(C 3 -C 8 cycloalkyl), halogen or cyano; R 3 represents (i) or (ii) or (iii) Q represents a heteroatom selected from O, N and S and if N may optionally be substituted with C 1-4 alkyl; Z represents CO or SO 2; Y 1 represents (CH 2) n and, except when n represents 0, may optionally be substituted by Me; X 1 represents (CH 2) m and, except when m represents 0, may optionally be substituted by Me; n and m independently represent 0, 1, 2, 3, 4 or 5; Y 2 represents (CH 2) s and may optionally be substituted by Me; s represents 2, 3, 4, 5 or 6; Y 3 represents (CH 2) t and may optionally be substituted by Me; X 2 represents (CH 2) v and may optionally be substituted by Me; t and v independently represent 2 or 3 save that t + v = 4 or 5; R 4 represents H, OH, NR 6 R 7 or an aliphatic 4-8 membered heterocycle containing one or more heteroatoms selected from O, N and S, save that when R 4 is OH or NR 6 R 7, m is 2, 3, 4 or 5; R 5 represents H, OH, NR 8 R 9 or aliphatic 4-8 membered heterocycle containing one or more heteroatoms selected from O, N and S save that when R 5 is OH or NR 8 R 9, n is 2, 3, 4 or 5; in which the aliphatic heterocycle groups that R 4 and R 5 may represent may optionally contain a carbonyl or sulphone group and may optionally be substituted by one or more groups selected from -C 1 -C 4 alkyl, C 1 -C 4 hydroxyalkyl-, C 1 -C 4 alkoxy(C 1 -C 4)alkyl-, -C 1 -C 4 alkyleneCONR 10 R 11, CN, OH and NR 12 R 13; R 6, R 7, R 8, R 9 independently represent H, or C 1 -C 4 alkyl optionally substituted by OH, oxo, NR 14 R 15 or-C 1 -C 4 alkoxy; and R 10, R 11, R 12, R 13, R 14 and R 15 independently represent H or C 1 -C 4 alkyl; or a pharmaceutically acceptable salt thereof.