Substituted purine derivative

A compound of formula (1):

• or a pharmaceutically acceptable salt thereof
• wherein
• R1 is optionally-substituted C1-6 alkoxy, optionally-substituted C3-7 cycloalkoxy, optionally-substituted 4- to 10-membered saturated heterocyclyloxy, optionally-substituted C1-6 alkyl, optionally-substituted C3-7 cycloalkyl, optionally-substituted C1-6 alkylthio, optionally-substituted 4- to 10-membered saturated heterocyclyl, optionally-substituted amino, halogen atom, or hydroxy;
• R2 is optionally-substituted C1-6 alkyl, optionally-substituted C3-7 cycloalkyl, or optionally-substituted amino;
• Ring Q1 is optionally-substituted C6-10 aryl, or optionally-substituted 5- to 10-membered heteroaryl;
• W1 is single bond, or optionally-substituted C1-4 alkylene;
• Ring Q2 is C6-10 aromatic carbocyclyl, or 5- to 10-membered aromatic heterocyclyl;
• n is 1, 2, 3, or 4;
• R3 is, independently if there are plural R3, hydrogen atom, halogen atom, cyano, hydroxy, optionally-substituted C1-6 alkyl, optionally-substituted C1-6 alkoxy, optionally-substituted C3-7 cycloalkyl, optionally-substituted C3-7 cycloalkoxy, or optionally-substituted amino;
• Q2-X1— is Q2-(single bond)-, Q2-(CH2)m—O—, Q2-(CH2)m—S—, Q2-(CH2)m—S(O)2—, Q2-(CH2)m—NRaS(O)2—, Q2-(CH2)m—S(O)2NRa—, Q2-(CH2)m—C(O)—, Q2-(CH2)m—NRa—, Q2-(CH2)m—NRaC(O)—, or Q2-(CH2)m—C(O)NRa—, wherein Ra is hydrogen atom or C1-6 alkyl;
• m is 0, 1, or 2;
• W2 is single bond, or optionally-substituted C1-8 alkylene;
• and
• R4 is hydrogen atom, —ORb (wherein Rb is hydrogen atom, optionally-substituted C1-6 alkyl, optionally-substituted C1-6 alkylcarbonyl, optionally-substituted aminocarbonyl, or optionally-substituted C1-6 alkylsulfonyl), —NRcRd (wherein Rc is hydrogen atom or optionally-substituted C1-6 alkyl;
• and Rd is hydrogen atom, optionally-substituted C1-6 alkyl, optionally-substituted C1-6 alkylcarbonyl, optionally-substituted C1-6 alkoxycarbonyl, or optionally-substituted C1-6 alkylsulfonyl), optionally-substituted 4- to 10-membered saturated heterocyclyl, or optionally-substituted 5- to 10-membered heteroaryl.