Compounds and their uses as cd38 inhibitors

A compound of formula I:

• wherein
• A1 is halogen;
• or 5 or 6 membered unsaturated monocyclic heterocycle containing 1 to 3 heteroatoms selected from the group consisting of N, O and S, and optionally substituted with one or two C1-6 alkyl optionally substituted with 1, 2 or 3 halogen;
• A2 is
• optionally having one or two carbon atoms replaced with nitrogen;
• wherein A2 is optionally substituted with 0 or 1 —OH;
• —CN;
• halogen;
• C1-6 alkyl optionally substituted with 1, 2 or 3 halogen;
• C2-6 alkynyl;
• 6 alkoxy;
• C3-6 cycloalkoxy, in which the cycloalkyl optionally has one carbon atom replaced with O or S:
• —NR1R2, in which each of R1 and R2 independently is H, C1-6 alkyl, —C(O)C1-6 alkyl;
• in which
• is a 5 or 6 membered saturated or unsaturated heterocycle containing 1 to 3 heteroatoms selected from the group consisting of N, O and S, and optionally substituted with 1-2 C1-6 alkyl;
• A3 is selected from the group consisting of
• C1-6 alkyl;
• —(CHR3)n—C3-8 cycloalkyl, in which the C3-8 cycloalkyl optionally has one or two carbon atoms replaced with N, O or S, n is 0, 1 or 2, and R3 is H or C1-6 alkyl;
• or
• in which the phenyl optionally has one or two carbon atoms replaced with N, k is 0, 1 or 2;
• wherein A3 is optionally substituted with 0, 1 or 2 substituents independently selected from the group consisting of —OH;
• —CN;
• —OCH2CH2OCH3;
• —CO—C1-6 alkyl;
• halogen;
• C1-6 alkyl optionally substituted with 1-3 halogen, methoxy or hydroxy;
• C1-6 alkoxy optionally substituted with NH2, dimethylamino, hydroxy or carboxy;
• C3-6 cycloalkoxy;
• or C3-8 cycloalkyl, in which the C3-8 cycloalkyl optionally has one or two carbon atoms replaced with N, O or S amd is optionally substituted with 1-3 halogen, C1-6 alkyl, C1-6 alkyl or hydroxy;
• R is H or C1-6 alkyl;
• or a pharmaceutically acceptable salt, ester, stereoisomer, tautomer, solvate, prodrug, or combination thereof.