Introduction A significant limitation of PARPi, that are used as maintenance treatment in ovarain cancer, is their toxicity profile. Many patients require discontinuation or dose modifications. To optimise patient longevity on treatment, clinical practices may consider individualised dosing for certain patients. Initiating reduced dosages, with or without dose escalation, may improve longterm toxicity and maximise duration of therapy. Little data is available on the impact of individualised dosing.

Methods A retrospective chart review was performed on 21 patients undergoing PARPi treatment in Cork between 2018 and 2023. Two cohorts were compared: those who received standard dose and those that received reduced-dose in the initial setting. Multiple toxicity profiles were assessed (haematological & non-haematological). Patient outcomes, hospitalisations, and dose reductions/interruptions/escalations were compared between the two subgroups.

Results Patients undergoing individualised treatment may have an improved toxicity profile compared to those prescribed standard regimens. The impact on progression-free survival between groups was indeterminate due to inter-sample variability. Patients undergoing individualised treatment had fewer events of vomiting (P = 0.476), severe nausea (P > 0.999), anaemia (P > 0.999) and leukopaenia (P > 0.999). Individualised treatment regimens showed a reduction in overall severe toxicities compared to the standard group (83% vs. 33%). Individualised treatment did not improve the proportion of patients experiencing thrombocytopenia.

Conclusion/Implications Individualised PARP inhibitor therapy may have a non-inferior impact on toxicity and progression-free survival in patients, however the statistical power of this study was limited by a small sample size and various confounding elements. Further research is needed support the results achieved herein.