Presentation and management of tislelizumab induced toxic optic neuropathy

Immune checkpoint inhibitors (ICIs) have revolutionised the management of advanced malignancies, but can cause immune-related adverse events (irAEs), including vision-threatening complications such as optic neuropathy. Ocular irAEs have been described with several programmed death-1/programmed death-ligand 1 and cytotoxic T lymphocyte-associated antigen-4 inhibitors, but ocular toxicities of tislelizumab have so far been limited to Vogt-Koyanagi-Harada (VKH)-like uveitis, panuveitis and retinal vasculitis. We describe a woman with metastatic lung adenocarcinoma who was treated with second-line gemcitabine, carboplatin and tislelizumab. After the second cycle of chemo-immunotherapy, she developed painless, progressive bilateral visual blurring in the absence of intracranial disease. Ophthalmic assessment was consistent with toxic optic neuropathy in the context of ongoing tislelizumab exposure, and other causes were excluded. Tislelizumab was discontinued and high-dose intravenous methylprednisolone (1 g/day for 5 days) was administered, without ICI re-challenge. Visual function did not improve, indicating an irreversible optic nerve injury. To our knowledge, this is the first reported case of toxic optic neuropathy associated with tislelizumab, extending the spectrum of tislelizumab-related ocular irAEs beyond previously documented VKH-like panuveitis, VKH-like uveitis and retinal vasculitis. This case highlights the importance of early recognition of visual symptoms and periodic ophthalmic assessment in patients receiving ICIs, as well as decision-making regarding ICI continuation or discontinuation when sight-threatening neuro-ophthalmic irAEs are suspected.