Next-generation sequencing in ocular oncology brings advances in diagnosis, management

(Image Credit: AdobeStock/Cavan)

Reviewed by J. William Harbour, MD

Next-generation sequencing (NGS), or massively parallel sequencing, is a recent advancement in DNA technology that allows for the analysis of genetic material much more quickly and at a lower cost than previously possible. Traditionally, analyzing genetic material required creating physical maps, performing single-gene sequencing, or using gene panels.

J. William Harbour, MD, an ocular oncology specialist, discussed how modern genetics advances the understanding of ocular cancer onset and progression during the Masonic Charity Foundation of Oklahoma Distinguished Lecture Series at the Dean McGee Eye Institute in Oklahoma City, Oklahoma. Harbour is a professor and holds the David Bruton Jr Chair in Ophthalmology at UT Southwestern Medical Center in Dallas, Texas.

Before NGS, DNA strands were sequenced from beginning to end in a time-intensive, laborious process. In a significant technological advance, NGS fragments the DNA into many pieces, sequences them individually, and then reassembles the desired section all at once.

NGS and retinoblastoma

Retinoblastoma, a childhood ocular cancer, has 2 forms: nonhereditary and hereditary. The nonhereditary form is unilateral, carries no increased risk of secondary cancers, and has a later onset. In contrast, the hereditary form is multifocal, bilateral, transmitted through autosomal dominant inheritance, carries an increased risk of secondary cancers, and manifests earlier.¹ Harbour emphasized that differentiating between these 2 forms in high-risk children is now possible overnight, compared to the months required before NGS.

A recent study² recommended dedicated ophthalmic screening for all children at risk for retinoblastoma above the general population’s risk. The frequency of examinations is adjusted based on the expected risk for the RB1 mutation. Genetic counseling and testing clarify retinoblastoma risk in children with a family history. Examination schedules are stratified for high-, intermediate-, and low-risk children, with high-risk children requiring more frequent screenings, often under anesthesia.

An “at-risk” patient is defined by the expert panel as an individual with a family history of retinoblastoma in a parent, sibling, or a first- or second-degree relative. The ability to rapidly identify children at higher risk for retinoblastoma at an early age enhances the management of this population.

Sequencing to identify RB1, the retinoblastoma gene, using traditional methods costs at least $4000 (~$8000 in 2024 dollars) and is typically not covered by insurance; however, NGS is more affordable and often covered by insurance.

NGS potential

The utility of NGS extends beyond identifying retinoblastoma, encompassing numerous eye diseases—both malignant and benign—and systemic cancers. Some systemic diseases characterized by ocular tumors include tuberous sclerosis, von Hippel-Lindau disease, and neurofibromatosis types 1 and 2. According to Harbour, genetic testing can now be performed rapidly and cost-effectively to diagnose these conditions accurately.

“In a patient with an ocular tumor, the clinician may be uncertain if it is retinoblastoma or tuberous sclerosis,” he said. “There are numerous ocular cancers, and having specific genetic information available is helpful without the need for a biopsy. A blood test or cheek swab may provide the information.”

Harbour described the case³ of a boy aged 12 years with bilateral retinal tumors and no family history. The differential diagnosis included retinal astrocytic hamartoma, retinoblastoma, and retinocytoma. Multimodal imaging and genetic testing confirmed bilateral retinocytoma. Germline genetic testing showed no mutations in the tuberous sclerosis complex subunit (TSC1 or TSC2) genes but identified a novel mutation in RB1, confirming bilateral retinocytoma in a patient with germline RB1 mutation.

Genetic information from NGS is crucial for patient and family counseling. It informs families about inheritance patterns and the potential for passing the gene to offspring. This knowledge can streamline treatment choices.

Finally, genetic testing provides prognostic insights. Harbour noted that a BAP1 mutation, for instance, indicates a poor prognosis in ocular melanoma, prompting consideration for clinical trial enrollment or close systemic metastasis monitoring.⁴ In contrast, an EIF1AX mutation suggests a favorable prognosis.⁵ “We are entering an exciting era of science and technology where the power of genetics can be harnessed to improve diagnosis, treatment, and quality of life for many more patients,” Harbour concluded.

J. William Harbour, MD

E: William.Harbour@UTSouthwestern.edu

Harbour is a professor, the David Bruton Jr Chair in Ophthalmology, and CPRIT Established Investigator in Cancer Research, UT Southwestern Medical Center, Dallas, Texas. He has a financial interest in the gene expression profiling related to BAP1.

References:

1. Knudson AG Jr. Mutation and cancer: statistical study of retinoblastoma. Proc Natl Acad Sci U S A. 1971;68(4):820-823. doi:10.1073/pnas.68.4.820

2. Skalet AH, Gombos DS, Gallie BL, et al. Screening children at risk for retinoblastoma: consensus report from the American Association of Ophthalmic Oncologists and Pathologists. Ophthalmology. 2018;125(3):453-458. doi:10.1016/j.ophtha.2017.09.001

3. Paez-Escamilla M, Walter SD, Ramaiya KJ, Harbour JW. Diagnosis of bilateral retinocytoma in an adolescent patient using multimodal imaging and genetic testing. Ophthalmic Surg Lasers Imaging Retina. 2018;49(10):812-814. doi:10.3928/23258160-20181002-11

4. Harbour JW, Onken MD, Roberson EDO, et al. Frequent mutation of BAP1 in metastasizing uveal melanomas. Science. 2010;330(6009):1410-1413. doi:10.1126/science.1194472

5. Field MG, Durante MA, Anbunathan H, et al. Punctuated evolution of canonical genomic aberrations in uveal melanoma. Nat Commun. 2016;7:14198. doi:10.1038/ncomms1419