a is 0 or an integer of from 1 to 5;

each R¹ is independently selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (3-6C)cycloalkyl, cyano, halo, —OR^1a, —C(O)OR^1b, —SR^1c, —S(O)R^1d, —S(O)₂R^1e, —NR^1fR^1g, —NR^1hS(O)₂R¹ⁱ, and —NR^1jC(O)R^1k; where each of R^1a, R^1b, R^1c, R^1d, R^1e, R^1f, R^1g, R^1h, R¹ⁱ, R^1j, and R^1k is independently hydrogen, (1-4C)alkyl or phenyl(1-4C)alkyl;

b is 0 or an integer of from 1 to 4;

each R² is independently selected from (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (3-6C)cycloalkyl, cyano, halo, —OR^2a, —C(O)OR^2b, —SR^2c, —S(O)R^2d, —S(O)₂R^2e, —NR^2fR^2g , —NR^2hS(O)₂R²ⁱ, and —NR^2jC(O)R^2k; where each of R^2a, R^2b, R^2c, R^2d, R^2e, R^2f, R^2g, R^2h, R²ⁱ, R^2j, and R^2k is independently hydrogen, (1-4C)alkyl or phenyl(1-4C)alkyl;

W represents O or NW^a, where W^a is hydrogen or (1-4C)alkyl;

c is 0 or an integer from 1 to 5;

each R³ independently represents (1-4C)alkyl or two R³ groups are joined to form (1-3C)alkylene, (2-3C)alkenylene or oxiran-2,3-diyl;

m is 0 or 1;

R⁴ is selected from hydrogen, (1-4C)alkyl, and (3-4C)cycloalkyl;

r is an integer from 2 to 4;

R⁵ is selected from hydrogen, (1-4C)alkyl, (3-4C)cycloalkyl, —C(O)(1-4C)alkyl, -(1-4C)alkyleneC(O)OR^5a, —C(O)heterocyclyl, —C(O)CH(NH₂)(1-4C)alkyleneQ, -(1-4C)alkyleneC(O)Z, —C(O)(1-4C)alkyleneZ, and —S(O)₂(1-4C)alkyleneZ; where Q is a nitrogen-containing substituent selected from —NR^5bR^5c and heteroaryl; Z is a nitrogen-containing substituent selected from —NR^5dR^5e and heterocyclyl; R^5a is hydrogen or (1-4C)alkyl; each of R^5b, R^5c, R^5d and R^5e independently represents hydrogen, (1-4C)alkyl, (3-6C)cycloalkyl or hydroxyphenyl, and where (1-4C)alkyl is unsubstituted or substituted by 1 or 2 substituents selected independently from amido, cyano, furyl, hydroxyl, and methylimidazolyl; the heterocyclyl contains 1 or 2 nitrogen atoms, and is unsubstituted or substituted by 1 or 2 substituents selected independently from hydroxyl, amido, (1-4C)alkoxy, oxo, —S(O)₂(1-4C)alkyl, —(CH₂)O(1-4C)alkyl, -(1-4C)alkyleneOH, —NR^5fR^5g and —C(O)NR^5hR⁵ⁱ, where each of R^5f, R^5g R^5h and R⁵ⁱ independently represents hydrogen or (1-4C)alkyl; and the heteroaryl contains 1 or 2 nitrogen atoms;

X¹ is selected from (1-3C)alkylene, —C(O)(1-3C)alkylene, (1-3C)alkyleneC(O)—, —SO₂—, —SO₂(1-3C)alkylene and (1-3C)alkyleneSO₂—; where the alkylene group in any X¹ is optionally substituted with 1 or 2 substituents independently selected from (1-4C)alkyl and —NR^XaR^Xb; wherein R^Xa and R^Xb are independently selected from hydrogen and (1-4alkyl);

p is 0, 1 or 2;

each R⁶ independently represents (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (3-6C)cycloalkyl, cyano, nitro, halo, N,N-di(1-4C)alkylamino(2-4C)alkoxy, —OR^6a, —C(O)OR^6b, —SR^6c, —S(O)R^6d, —S(O)₂R^6e or —NR^6fR^6g; each of R^6a, R^6b, R^6c, R^6d, R^6e, R^6f and R^6g is independently hydrogen, (1-4C)alkyl, (3-6C)cycloalkyl, phenyl or phenyl(1-4C)alkyl, wherein each phenyl group is unsubstituted or substituted by 1 or 2 substituents selected independently from halo, (1-4C)alkyl and (14C)alkoxy; and

wherein each alkyl and alkoxy group in R¹, R^1a-1k, R², R^2a-2k, R³, R⁶, and R^6a-6g is optionally substituted with 1 to 5 fluoro substituents;

or a pharmaceutically acceptable salt or solvate or stereoisomer thereof.