Most frequently, immune-related Adverse Events (irAEs) affect a wide range of organs like skin, colon, liver, pituitary, thyroid, and lungs, although uncommon events involving the heart, nervous system, and other organs do occur. The onset develops predominantly within the first 6-12 weeks after treatment initiation.
Combining treatment with ipilimumab and nivolumab has resulted in a reported 18%-22% all-grade hepatitis and overall with 8%-11% having severe hepatitis. (Remash D, et al. World J Gastroenterol. 2021)
Hyperthyroidism due to irThyroiditis occurs on account direct thyreocyte destruction and hence carbimazole, which acts by inhibiting thyroid hormone synthesis is not indicated in irHyperthyroidism. (Iyer PC, et al. Thyroid. 2018).
Neurological immune-related adverse events occur in 1%–5% of patients on ICI therapy (Koch EAT, et al. J Immunother. 2021). Moreover, ICI-mediated ototoxicity is rare or under reported due to a small number of case reports published till date. (Rosner S, et al. J Immunother Cancer, 2020) of patients (refs voskens JCO, and others). It may develop isolated as a single irAE or in concert with other irAEs as in this case. Manifestation of ICI-mediated ototoxicity ranges from isolated hearing loss, tinnitus, vestibular symptoms with hearing loss, visual and hearing loss or Vogt-Koyanagi-Harada syndrome (VKH) with ocular, dermatologic and neurologic involvement. It is important to distinguish between isolated hearing changes and hearing changes as part of a collective syndrome to institute appropriate management.
In the absence of ocular involvement, a diagnosis of Cogan Syndrome was not made.
ICI-mediated ototoxicity occurs early in the treatment course (within ~4 months of initiating ICI). The association between irAEs and ICI efficacy is controversial and may depend on the site of toxicity. Retrospective studies suggest that site-specific toxicities may have a correlation with ICI efficacy (Martins F, et al. Nat Rev Clin Oncol, 2019)
The mechanisms underlying the development of ICI-mediated ototoxicity are currently unknown. Preclinical rat models of ICI-mediated ototoxicity demonstrated significant differences in auditory brainstem responses (ABR) in those treated with ICIs vs controls, as well as pathologic evidence of a reduction in the outer hair cells and flattening of the organ of Corti in those treated with ICI. (Kuzucu İhsan, et al . Cureus 2019) Interestingly, ototoxicity has also been reported from adoptive cell therapy for melanoma. The proposed mechanism of this toxicity could involve auto-antigenicity against melanocyte specific antigens such as MART-1 present in the inner ear, uvea and epithelium of the skin (Plonka PM et al. Exp Dermatol, 2009).