R¹ is selected from hydrogen, C_1-6alkyl optionally substituted by up to three groups independently selected from C_1-6alkoxy, halogen and hydroxy, C_2-6alkenyl, C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups, phenyl optionally substituted by up to three groups independently selected from R⁵ and R⁶ or heteroaryl optionally substituted by up to three groups independently selected from R⁵ and R⁶,

R² is selected from hydrogen, C_1-6alkyl or —(CH₂)_p—C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups,

or (CH₂)_mR¹ and R², together with the nitrogen atom to which they are bound, form a four- to six-membered heterocyclic ring optionally substituted by up to three C_1-6alkyl groups;

R³ is chloro or methyl;

R⁴ is the group —NH—CO—R⁷ or —CO—NH—(CH₂)_p—R⁸;

R⁵ is selected from C_1-6alkyl, C_1-6alkoxy, —(CH₂)_p—C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups, —CONR⁹R¹⁰, —NHCOR¹⁰, —SO₂NHR⁹, —CH₂)_qNHSO₂R¹⁰, halogen, CN, OH, —(CH₂)_qNR¹¹R¹² or trifluoromethyl;

R⁶ is selected from C_1-6alkyl, C_1-6alkoxy, halogen, trifluoromethyl or —(CH₂)_qNR¹¹R¹²;

R⁷ is selected from hydrogen, C_1-6alkyl, —(CH₂)_p—C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups, trifluoromethyl, —(CH₂)_rheteroaryl optionally substituted by R¹³ and/or R¹⁴ or —(CH₂)_rphenyl optionally substituted by R¹³ and/or R¹⁴;

R⁸ is selected from hydrogen, C_1-6alkyl, C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups, CONHR⁹, phenyl optionally substituted by R¹³ and/or R¹⁴ or heteroaryl optionally substituted by R¹³ and/or R¹⁴;

R⁹ and R¹⁰ are each independently selected from hydrogen or C_1-6alkyl, or

R⁹ and R¹⁰, together with the nitrogen atom to which they are bound, form a five- to six-membered heterocyclic ring optionally containing one additional heteroatom selected from oxygen, sulfur and N—R¹⁵, wherein the ring is optionally substituted by up to two C_1-6alkyl groups;

R¹¹ is selected from hydrogen, C_1-6alkyl or —(CH₂)_p—C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups;

R¹² is selected from hydrogen or C_1-6alkyl, or

R¹¹ and R¹², together with the nitrogen atom to which they are bound, form a five or six-membered heterocyclic ring optionally containing one additional heteroatom selected from oxygen, sulfur and N—R¹⁵;

R¹³ is selected from C_1-6alkyl, C_1-6alkoxy, —CH₂)_p—C_3-7cycloalkyl optionally substituted by one or more C_1-6alkyl groups, —CONR⁹R¹⁰, —NHCOR¹⁰, halogen, CN, —(CH₂)_qNR¹¹R¹², trifluoromethyl, phenyl optionally substituted by one or more R¹⁴ groups or heteroaryl optionally substituted by one or more R¹⁴ groups;

R¹⁴ is selected from C_1-6alkyl, C_1-6alkoxy, halogen, trifluoromethyl or —NR¹¹R¹²;

R¹⁵ is selected from hydrogen or methyl;

X and Y are each independently selected from hydrogen, methyl or halogen;

Z is selected from —(CH₂)_sOR¹⁶, —(CH₂)_sNR¹⁶R¹⁷, —(CH₂)_sCH₂CH₂R¹⁶, —(CH₂)_sCOOR¹⁶, —(CH₂)_sCONR¹⁶R¹⁷, —(CH₂)_sNHCONR¹⁶R¹⁷, —(CH₂)_sSO₂R¹⁶, —(CH₂)_sSO₂NR¹⁶R¹⁷ or —(CH₂)_sNHSO₂R¹⁶;

R¹⁶ is selected from hydrogen, C_1-6alkyl optionally substituted by up to two hydroxy groups, —(CH₂)_tOR¹⁸, —(CH₂)_tNR¹⁸R¹⁹, —(CH₂)_tNHSO₂R¹⁸, —(CH₂)_tCONR¹⁸R¹⁹, —(CH₂)_tCOOR¹⁸, —(CH₂)_theteroaryl optionally substituted by up to two groups independently selected from halogen, C_1-6alkyl or oxo, or —(CH₂)_tphenyl optionally substituted by up to two groups independently selected from halogen, C_1-6alkyl or C_1-6alkoxy,

R¹⁷ is selected from hydrogen or C_1-6alkyl, or

R¹⁶ and R¹⁷, together with the nitrogen atom to which they are bound, form a five- to six-membered heterocyclic ring optionally containing one additional heteroatom selected from oxygen, sulfur and N—R¹⁵, wherein the ring is optionally substituted by up to two groups independently selected from oxo, halogen or C_1-6alkyl;

R¹⁸ and R¹⁹ are each independently selected from hydrogen or C_1-6alkyl optionally substituted by up to two hydroxy groups, or

R¹⁸ and R¹⁹, together with the nitrogen atom to which they are bound, form a five- to six-membered heterocyclic ring optionally containing one additional heteroatom selected from oxygen, sulfur and N—R¹⁵, wherein the ring is optionally substituted by up to two groups independently selected from oxo, halogen or C_1-6alkyl;

m is selected from 0, 1, 2, 3 or 4, wherein each carbon atom of the resulting carbon chain may be optionally substituted with up to two groups independently selected from C_1-6alkyl or halogen;

n is 1;

p is selected from 0, 1 or 2;

q is selected from 0, 1, 2 or 3;

r is selected from 0 or 1;

s is selected from 0, 1, 2, 3 and 4; and

t is selected from 1,2, 3or 4;

or a pharmaceutically acceptable salt thereof.