The invention relates to substituted quinazolin-4-one compounds of the formula (I) and/or pharmaceutically acceptable salts and/or solvates thereof, wherein R1, R2, R3, R5, R6 and L are as defined in the description. Such compounds are suitable for the treatment of a disorder or disease which is mediated by the activity of the class I PI3K kinases.本發明係關於式(I)經取代的喹唑啉-4-酮化合物及/或其醫藥上可接受的鹽及/或溶劑化物,其中R1、R2、R3、R5、R6及L係如說明書中所定義。此等化合物適合用於治療由I類PI3K激酶活性介導之病症或疾病。