Characterization of Belantamab Mafodotin–Induced Corneal Changes in Patients With Multiple Myeloma

Importance Ocular surface events are a class effect of microtubule-inhibitor payload-containing antibody-drug conjugates (ADCs); the mechanism underlying these events has not been fully elucidated. Objective To characterize corneal epithelial changes in patients with relapsed or refractory multiple myeloma (RRMM) treated with belantamab mafodotin, a maleimidocaproyl monomethyl auristatin-F (MMAF)–containing ADC. Design, Setting, and Participants This multicenter, phase 3b case series study was conducted in the US from March 26, 2020, to November 21, 2022, among adults with RRMM. Data were analyzed from May 2021 to May 2023. Exposure Prior or ongoing treatment with belantamab mafodotin. Main Outcomes and Measures The primary end point included pathologic characteristics and composition of corneal epithelial changes obtained by impression cytology (IC) or superficial keratectomy (SK) in patients treated with belantamab mafodotin. Tear film and blood were collected to determine belantamab mafodotin concentrations in patients at the time of sampling. Results Of 16 patients screened, 9 were included in this study, with 6 evaluable corneal samples obtained from 6 patients either by IC (n = 4) or SK (n = 2). Of 9 patients included, median (range) patient age was 67.0 (57.0-81.0) years for those with samples obtained by IC and 68.0 (65.0-81.0) years for those with samples obtained by SK. Six patients (67%) were female. All samples demonstrated epithelial cells with eosinophilic intracytoplasmic inclusions, basophilic granular cytoplasm, or both. Five samples were positive for apoptosis, and 3 samples showed evidence of inflammation. All patients experienced complete IC or SK wound healing. ADC was detected in the tear fluid of 5 of 7 patients with tear fluid sampling, while ADC was quantifiable in 3 of 4 patients with blood samples. Conclusions and Relevance In this case series study, intracytoplasmic inclusions were observed by histopathology in the corneal epithelium of patients exposed to belantamab mafodotin, and the pattern of corneal changes suggests limbal vessels may be a primary pathway enabling ADC to reach the cornea. Although limited to 6 samples, this study helps us better understand corneal changes associated with certain ADCs. Trial Registration ClinicalTrials.gov Identifier: NCT04549363