Retinoblastoma: Aqueous humor liquid biopsy

Abstract

Advances in retinoblastoma (RB) therapy have led to significantly improved ocular preservation rates, consequently limiting access to histologic and genomic information traditionally obtained from enucleated eyes. Moreover, genomic information from enucleated specimens often represents heavily pretreated, refractory disease. The introduction of aqueous humor (AH) biopsy marks a significant milestone in ocular oncology, offering in vivo, real-time tumoral genomic data that can be collected at diagnosis and repeatedly throughout treatment. This liquid biopsy has detected RB1 gene mutations and deletions and identified potential clinical biomarkers, such as amplification of the 6p chromosomal region and the MYCN gene. In addition, monitoring trends in tumor fraction provides dynamic insights into disease progression. While further research is required to validate these findings in larger populations and uncover new biomarkers, the scientific community has shown growing interest in the clinical potential of this novel approach. AH biopsy is a safe and reproducible procedure that supports precision oncology by providing tumor-specific genomic data for each patient and eye.

Keywords: Aqueous humor; biomarkers; liquid biopsy; prognosis; retinoblastoma.

Figure 1

Aqueous humor (AH) biopsy. Tumor-derived cell-free deoxyribonucleic acid is present in the AH. Approximately 100μL of AH is collected via a simple corneal paracentesis using a 32G needle. (Created with Biorender.com)

Figure 2

Somatic copy number alteration (SCNA) amplitude and TFx values correspond to clinical therapeutic response. (a) Genomic profiles of six sequential aqueous humor (AH) samples extracted from a single eye during Intravitreal Melphalan (IVM) therapy for tumor seeding (* = 6p gain or 16q loss). (b) Changes in SCNA amplitude correspond to clinical regression (R) and progression (P) at each sampling timepoint. (c) Changes in TFx correspond to clinical regression (R) and progression (P) at each sampling timepoint. (d) Fundus photographs of the affected eye over the course of 6 injections of IVM. Reduction of vitreous seeding and tumor size occurred between injections 2 through 5, whereas a large recurrence of the retinal tumor (arrow) was noted on the day of injection 6. (From Polski et al. Cell-Free DNA Tumor Fraction in the AH is associated with Therapeutic Response in Retinoblastoma Patients). SCNA = Somatic copy number alterations. TFx = Tumor fraction. IVM = Intravitreal melphalan AH = Aqueous humor