Mutant-RB1 circulating tumor DNA in the blood of unilateral retinoblastoma patients: What happens during enucleation surgery: A pilot study

Histiocytosis Advancements Parallel Ophthalmic Innovations: The LXXXI Edward Jackson Memorial Lecture

PURPOSE

To highlight innovations in ophthalmic oncology through histiocytosis advancements.

DESIGN

Perspective and retrospective review.

METHODS

The literature outlining the recent advancements in histiocytosis and ocular oncology was reviewed and combined with trial data and personal recollection. Intersections between these two fields were discussed.

RESULTS

The understanding of genetic mutations in disease-both in which cells they occur and the timing of mutation development-has expanded in tandem for the fields of ophthalmic oncology and histiocytosis. Similarly, advancements in diagnostic and treatment technology in one field can help patients in the other. For example, in one study, cell-free DNA testing reliably detected mutations in 14 of 18 (78%) patients with suspected histiocytosis. This technique has also been used in ophthalmic oncology as an alternative to invasive biopsy to avoid the risk of tumor externalization, vision impairment, and other side effects. These and other advancements have allowed both fields to utilize targeted agents to successfully treat diseases with an actionable mutation; or deliver more targeted chemotherapy via the intraarterial technique.

CONCLUSIONS

The explosion of molecular genetics technology and targeted therapies has revolutionized cancer treatment, including histiocytosis and ophthalmic oncology. Recent progress in both fields has shown how these seemingly disparate areas have many intersections, and this speaks to the collaborative spirit that is inherent in clinical research.

PLASMA CIRCULATING TUMOR DNA TO ASSIST IN THE DIAGNOSIS OF UNKNOWN PRIMARY MALIGNANCY UNDERLYING CHOROIDAL METASTASES

PURPOSE

Management of suspected choroidal metastases requires diagnostic imaging and an invasive, sometimes intraocular, biopsy to determine the primary malignancy. This multistep process takes time, which may affect morbidity and mortality.

METHODS

This was a retrospective review of one case.

RESULTS

A 56-year-old woman presented with bilateral amelanotic choroidal masses suspicious for metastases of unknown origin. Plasma circulating tumor DNA revealed EGFR , PTEN , and SMAD4 , a profile consistent with non-small-cell lung cancer. Subsequent radiographic imaging and scapular biopsy revealed lung adenocarcinoma and genetic profile concordant with the liquid biopsy. The patient was started on EGFR inhibitor, osimertinib, with measurable systemic and ocular response.

CONCLUSION

Plasma circulating tumor DNA revealed the genetic profile of the primary malignancy underlying choroidal metastases of unknown origin, aiding in the prompt diagnosis and detecting the driver mutation that guided management with targeted therapy.

RB1 CIRCULATING TUMOR DNA IN THE BLOOD OF PATIENTS WITH RETINOBLASTOMA INCREASES IN UNTREATED PATIENTS

PURPOSE

Circulating tumor DNA (ctDNA) in plasma has been identified in many cancers, including retinoblastoma at diagnosis. It has previously been shown that with treatment (enucleation or ophthalmic artery chemosurgery), all ctDNA disappears; if there is persistent plasma ctDNA after treatment, metastases develop. The purpose of this study was to determine how the ctDNA RB1 variant allele frequency changes in patients with retinoblastoma who have delayed treatment.

METHODS

Circulating tumor DNA RB1 was detected, and variant allele frequency was measured at diagnosis and again before any intervention at some time later ranging from 2 days to 28 days.

RESULTS

Four patients with five ctDNA RB1 mutations were detected at diagnosis, and variant allele frequency was increased on reevaluation of the same RB1 mutations in ctDNA.

CONCLUSION

In this small cohort, every patient (4) and every RB1 mutation (5) plasma level VAF% increased when measured at two time periods before treatment was initiated suggesting that growing tumors demonstrate increasing plasma ctDNA.

Circulating Tumor DNA Posttreatment Measurements and Clinical Correlates in Retinoblastoma

Importance

Plasma measurements of RB1 circulating tumor DNA (ctDNA) after completion of treatment may be associated with the development of metastases in patients with retinoblastoma.

Objective

To determine if the absence of previously detectable plasma ctDNA is associated with metastasis-free survival in patients with a minimum of 1 year follow-up after treatment of retinoblastoma.

Design, Setting, and Participants

This cohort study was conducted from June 2019 to September 2023. Patients with retinoblastoma who had measurable ctDNA levels at diagnosis and had repeated ctDNA measurements after ocular treatment (enucleation or intra-arterial chemotherapy) with a minimum of 1 year of follow-up (mean [SD], 28.2 [10.3] months) were included in the study. Patients were recruited from a single-center, tertiary cancer hospital.

Exposure

Memorial Sloan Kettering's New York State-approved gene test, which interrogates 129 known cancer genes (called ACCESS), was performed on plasma samples before and after ocular treatments. All exons of the RB1 gene are included in the test and listed as ctDNA in this article.

Main Outcomes and Measures

Plasma ctDNA level before treatment, after completion of ocular treatment, and development or absence of metastases.

Results

A total of 24 patients (mean [SD] age, 20.7 [17.1] months; 15 female [62.5%]) were included in the study. None of the 23 patients who had a measurable ctDNA level and then no detectable ctDNA level after completion of ocular treatment developed metastases with a minimum of 1 year of follow-up. One patient had persistent measurable ctDNA after initial treatment and developed metastases.

Conclusion and Relevance

Patients with retinoblastoma who had a measurable ctDNA level at diagnosis did not develop metastases if the plasma ctDNA level became unrecordable after ocular treatment; 1 patient who had persistent measurable ctDNA after treatment did develop metastasis.