A composition comprising a cell or a population of cells that expresses a CAR molecule that binds CD19 (a "CAR19-expressing cell") for use, in combination with a Bruton's tyrosine kinase (BTK) inhibitor, in the treatment of a disease associated with expression of CD19 in a mammal, wherein the disease is an autoimmune disease, an inflammatory disorder or a cancer, wherein the BTK inhibitor comprises a compound of formula (I) or a pharmaceutically acceptable salt thereof; wherein, R1 is hydrogen, C 1 -C 6 alkyl optionally substituted by hydroxy; R2 is hydrogen or halogen; R3 is hydrogen or halogen; R4 is hydrogen; R5 is hydrogen or halogen; or R4 and R5 are attached to each other and stand for a bond, -CH 2 -, -CH 2 -CH 2 -, -CH=CH-, -CH=CH-CH 2 -; -CH 2 -CH=CH-; or -CH 2 -CH 2 -CH 2 -; R6 and R7 stand independently from each other for H, C 1 -C 6 alkyl optionally substituted by hydroxyl, C 3 -C 6 cycloalkyl optionally substituted by halogen or hydroxy, or halogen; R8, R9, R, R', R10 and R11 independently from each other stand for H, or C 1 -C 6 alkyl optionally substituted by C1-C6 alkoxy; or any two of R8, R9, R, R', R10 and R11 together with the carbon atom to which they are bound may form a 3 - 6 membered saturated carbocyclic ring; R12 is hydrogen or C 1 -C 6 alkyl optionally substituted by halogen or C 1 -C 6 alkoxy; or R12 and any one of R8, R9, R, R', R10 or R11 together with the atoms to which they are bound may form a 4, 5, 6 or 7 membered azacyclic ring, which ring may optionally be substituted by halogen, cyano, hydroxyl, C 1 -C 6 alkyl or C 1 -C 6 alkoxy; n is 0 or 1; and R13 is C 2 -C 6 alkenyl optionally substituted by C 1 -C 6 alkyl, C 1 -C 6 alkoxy or N,N-di-C 1 -C 6 alkyl amino; C 2 -C 6 alkynyl optionally substituted by C 1 -C 6 alkyl or C 1 -C 6 alkoxy; or C 2 -C 6 alkylenyl oxide optionally substituted by C 1 -C 6 alkyl. R1 is hydrogen, C 1 -C 6 alkyl optionally substituted by hydroxy; R2 is hydrogen or halogen; R3 is hydrogen or halogen; R4 is hydrogen; R5 is hydrogen or halogen; or R4 and R5 are attached to each other and stand for a bond, -CH 2 -, -CH 2 -CH 2 -, -CH=CH-, -CH=CH-CH 2 -; -CH 2 -CH=CH-; or -CH 2 -CH 2 -CH 2 -; R6 and R7 stand independently from each other for H, C 1 -C 6 alkyl optionally substituted by hydroxyl, C 3 -C 6 cycloalkyl optionally substituted by halogen or hydroxy, or halogen; R8, R9, R, R', R10 and R11 independently from each other stand for H, or C 1 -C 6 alkyl optionally substituted by C1-C6 alkoxy; or any two of R8, R9, R, R', R10 and R11 together with the carbon atom to which they are bound may form a 3 - 6 membered saturated carbocyclic ring; R12 is hydrogen or C 1 -C 6 alkyl optionally substituted by halogen or C 1 -C 6 alkoxy; or R12 and any one of R8, R9, R, R', R10 or R11 together with the atoms to which they are bound may form a 4, 5, 6 or 7 membered azacyclic ring, which ring may optionally be substituted by halogen, cyano, hydroxyl, C 1 -C 6 alkyl or C 1 -C 6 alkoxy; n is 0 or 1; and R13 is C 2 -C 6 alkenyl optionally substituted by C 1 -C 6 alkyl, C 1 -C 6 alkoxy or N,N-di-C 1 -C 6 alkyl amino; C 2 -C 6 alkynyl optionally substituted by C 1 -C 6 alkyl or C 1 -C 6 alkoxy; or C 2 -C 6 alkylenyl oxide optionally substituted by C 1 -C 6 alkyl. <EOS>