Supplementary Material for: Diffuse infiltrating retinoblastoma with anterior chamber involvement: conservative management and identification of RB1 alterations in aqueous humor

Purpose: The aim of the study was to describe the successful conservative management of diffuse infiltrating retinoblastoma (DIR). Identification of RB1 pathogenic variant was done after cell-free DNA (cfDNA) analysis in aqueous humor. Methods: We conducted a retrospective case series. Results: We report 2 patients with unilateral, non-familial DIR with anterior and posterior involvement. Both patients underwent liquid biopsy for tumor cfDNA analysis on aqueous humor. Treatment consisted in combination of systemic and intra-arterial chemotherapy, with consecutive intracamerular and intravitreal injections of melphalan. One patient also required Iodine 125 brachytherapy. In both cases tumor cfDNA analysis revealed biallelic somatic alterations of the RB1 gene. These alterations were not found on germline DNA. Both patients retained their eyes and had a useful vision after a follow-up of 2 years. Conclusion: In selected cases, conservative management of DIR is safe and effective. Tumor cfDNA analysis in aqueous humor is an effective technique to disclose RB1 somatic alterations that guide the germline molecular explorations and improve genetic counselling after conservative treatment.