# Characterization of exceptional responders with long-term PARP inhibitor therapy in recurrent ovarian cancer: an analysis of 23 patients from Charité

## TL;DR

This study examines 23 patients with recurrent ovarian cancer who responded exceptionally well to long-term PARP inhibitor therapy, highlighting treatment duration, side effects, and management challenges.

## Contribution

The study characterizes patients with long-term response to PARP inhibitors in ovarian cancer, providing insights into treatment duration and adverse events.

## Key findings

- Patients receiving PARP inhibitors for at least 5 years showed a median treatment duration of 7.1 years.
- BRCA1 mutation patients had the longest treatment duration, averaging 8 years.
- Adverse events were common, with 69.7% of patients needing dose reductions or experiencing side effects.

## Abstract

This analysis aimed to characterize exceptional responder with long-term PARP inhibitor therapy (ExR-LT) in platinum-sensitive recurrent ovarian cancer.

This analysis included ExR-LT. ExR-LTs are defined as patients that received a continuous maintenance therapy for recurrent ovarian cancer with olaparib or niraparib for at least 5 years and showed an exceptional response. Exceptional response was defined as progression-free survival (PFS) of at least 5 years. This analysis has a retrospective and descriptive character.

23 patients were included. The median duration of PARPi therapy was 7.1 years (range 5.3; 10.5). The longest treatment duration was reached in the BRCA1 mutation (BRCA1m) cohort with a mean duration of 8 years (range 5.3; 10.5 years). The majority of patients (16 patients, 69.7%) reported adverse events (AE) during PARPi therapy. 12 patients (52.2%) had mild AE (CTCAE 1 or 2), 4 patients (17.4%) reported more severe AE (CTCAE 3). 14 patients needed a dose reduction due to treatment-related AE (60.1%). The most common indications for dose reduction were anemia (17.4%), headache and limb pain (17.4%), and fatigue (13%). Four patients (17.4%) required an interruption of PARPi therapy. Ten patients received a dose reduction within the first 6 months and two patients after one and 1.3 years of PARPi therapy. No dose adjustments were necessary between 1.5 and 4 years. After 4 years, 3 patients (13%) received a late dose reduction. 8.6% had another cancer diagnosed before, 4.3% simultaneously, and 13% after the ovarian cancer diagnosis.

ExR-LTs present with heterogenic clinical and genetic characteristics. Clinical management is complex because of a high rate of AE and need of dose reductions at various points in time. Close monitoring for AE, recurrences and secondary malignancies must be carried out throughout the entire time of treatment.