Disclosed herein is a method for the prevention, delay of progression or treatment of cancer in a subject, comprising administering to the subject in need thereof a PARP inhibitor, particularly, (R)-2-fluoro-10a-methyl-7,8,9,10,10a,11-hexahydro-5,6,7a,11-tetraazacyclohepta[def]cyclopenta[a]fluoren-4(5H)-one, a sesqui-hydrate thereof, or a pharmaceutically acceptable salt thereof, in combination with an immune checkpoint inhibitor or a chemotherapeutic agent. Also, disclosed a pharmaceutical combination comprising a PARP inhibitor, particularly, (R)-2-fluoro-10a-methyl-7,8,9,10,10a,11-hexahydro-5,6,7a,11-tetraazacyclohepta[def]cyclopenta[a]fluoren-4(5H)-one, a sesqui-hydrate thereof, or a pharmaceutically acceptable salt thereof, in combination with an immune checkpoint inhibitor, or a chemotherapeutic agent and the use thereof.