Molecular diagnosis of retinoblastoma by circulating tumor DNA analysis
Irene Jiménez1, Éléonore Frouin2, Mathieu Chicard1
1SiRIC RTOP « Recherche Translationelle en Oncologie Pédiatrique », Translational Research Department, PSL Research University, Institut Curie Research Center, Paris, France; INSERM U830, Equipe Labellisée Ligue Contre le Cancer, PSL Research University, Institut Curie Research Center, Paris, France; Department of Translational Research, Institut Curie Research Center, Paris, France; SIREDO Center: Care, Innovation and Research for Children, Adolescents and Young Adults with Cancer, Institut Curie, Paris, France.
Purpose:
The analysis of circulating tumor DNA (ctDNA), a fraction of total cell-free DNA (cfDNA), might be of special interest in retinoblastoma patients. Because the accessibility to tumor tissue is very limited in these patients, either for histopathological diagnosis of suspicious intraocular masses (biopsies are proscribed) or for somatic RB1 studies and genetic counseling (due to current successful conservative approaches), we aim to validate the detection of ctDNA in plasma of non-hereditary retinoblastoma patients by molecular analysis of RB1 gene.
Experimental Design:
In a cohort of 19 intraocular unilateral non-hereditary retinoblastoma patients for whom a plasma sample was available at diagnosis, we performed high-deep next-generation sequencing (NGS) of RB1 in cfDNA. Two different bioinformatics/statistics approaches were applied depending on whether the somatic RB1 status was available or not.
Results:
Median plasma sample volume was 600 μL [100-1000]; median cfDNA plasma concentration was 119 [38-1980] and 27 [11-653] ng/mL at diagnosis and after complete remission, respectively. In the subgroup of patients with known somatic RB1 alterations (n = 11), seven of nine somatic mutations were detected (median allele fraction: 6.7%). In patients without identified somatic RB1 alterations (n = 8), six candidate variants were identified for seven patients.
Conclusions:
Despite small tumor size, blood-ocular barrier, poor ctDNA blood release and limited plasma sample volumes, we confirm that it is possible to detect ctDNA with high-deep NGS in plasma from patients with intraocular non-hereditary retinoblastoma. This may aid in diagnosis of suspicious cases, family genetic counseling or follow-up of residual intraocular disease.
Insights
Detecting circulating tumor DNA (ctDNA) in retinoblastoma patients
Area of Science:
- Oncology
- Genetics
- Ophthalmology
Background:
- Limited tumor tissue accessibility in retinoblastoma hinders diagnosis and genetic studies.
- Conservative treatment approaches necessitate non-invasive monitoring methods.
Purpose of the Study:
- To validate the detection of circulating tumor DNA (ctDNA) in plasma of non-hereditary retinoblastoma patients.
- To assess the feasibility of RB1 gene molecular analysis in cell-free DNA (cfDNA).
Main Methods:
- High-deep next-generation sequencing (NGS) of the RB1 gene in cfDNA from 19 retinoblastoma patients.
- Application of two distinct bioinformatics/statistical approaches for variant detection.
- Analysis of plasma samples collected at diagnosis and during remission.
Main Results:
- ctDNA was detectable in plasma samples from patients with intraocular non-hereditary retinoblastoma.
- Seven of nine known somatic RB1 mutations were identified in a subgroup of patients.
- Six candidate RB1 variants were detected in patients without initially identified somatic alterations.
Conclusions:
- High-deep NGS enables ctDNA detection in retinoblastoma plasma, despite challenges like small tumor size and blood-ocular barrier.
- ctDNA analysis can potentially assist in diagnosing suspicious cases.
- This approach may support family genetic counseling and monitoring of residual disease.
