Prolonged Progression-Free Survival in a Patient with Highly Pretreated Recurrent Ovarian Cancer after Developing Multisystem Immune-Related Adverse Events: A Case Report and Literature Review

Introduction: The development of immune-related adverse events (irAEs) has been associated with improved survival from various solid tumors. Given that immunotherapy has not been widely used in ovarian cancer and has only been applied to patients with high tumor mutational burden or microsatellite instability, studies exploring the effects of irAEs on ovarian cancer have been limited. Case Presentation: A 47-year-old woman was diagnosed with International Federation of Gynecology and Obstetrics stage III ovarian cancer in 2013. Between 2013 and 2021, she underwent palliative chemotherapy comprising paclitaxel liposomes, cisplatin/nedaplatin, S-1/raltitrexed, irinotecan, doxorubicin, vinorebine, toripalimab, apatinib, gemcitabine, oxaliplatin, and capecitabine, as well as two debulking surgeries. From November 2021, she received six cycles of tislelizumab (a PD-1 inhibitor), paclitaxel (albumin-bound), and carboplatin, to which a partial response was observed according to the Response Evaluation Criteria in Solid Tumors. From May 2022, the patient was switched to maintenance therapy with tislelizumab plus olaparib. However, all antitumor treatments were discontinued from April 2023 due to multiple irAEs, including hypothyroidism, adrenal insufficiency, and pneumonitis, with the tumor remaining stable until November 2023. Progression-free survival (PFS) was approximately 24 months with tislelizumab-containing therapy but was 18 months with tislelizumab/olaparib maintenance therapy. Conclusions: We report a case involving a patient with highly pretreated recurrent ovarian cancer who exhibited prolonged PFS after developing three irAEs. The distinctly prolonged PFS observed, along with the reviewed literature, suggests that irAEs may be correlated with improved survival in ovarian cancer.