Research on ovarian cancer suggests that dipeptidyl peptidase 4 (DPP4) may suppress the anti-tumour chemokine response induced by PARP inhibitors. However, the effectiveness of PARP inhibitors in other types of cancer, such as small cell lung cancer, may be enhanced when combined with other therapies. Additionally, other potential therapeutic targets, including RECQL1, are being explored for treating ovarian cancer that is resistant to PARP inhibitors.