Retrospective Evaluation of Somatic Alterations in Cell-Free DNA from Blood in Retinoblastoma

Abstract

Abstract Purpose Analysis of circulating tumor DNA (ctDNA) in the plasma of retinoblastoma patients and simulating lesions. Design Retrospective cross-sectional study of association of plasma ctDNA from retinoblastoma and simulating lesions with disease course. Participants Fifty-eight MSKCC retinoblastoma patients with 68 plasma ctDNA samples and 5 with retinoblastoma simulating lesions. Methods The ctDNA analyzed with hybridization capture and next generation sequencing in blood plasma of patients who had retinoblastoma or simulating lesions were evaluated for association with clinical course of the disease. Main Outcome Measure Presence or absence of molecular aberrations in the RB1 gene and correlations with clinical features. Results RB1 cell free DNA was detected in 16 of 19 patients with newly diagnosed, untreated intraocular retinoblastoma and in 3 of 3 patients with newly diagnosed, untreated metastatic disease. It was also present in 3 patients with recurrent intraocular disease before therapy but not present in patients with recurrent disease who were receiving intraarterial chemotherapy or in 21 patients who had been enucleated for unilateral disease. In 1 patient who had delayed treatment (insurance reasons) and rapid growth of the intraocular tumor the VAF increased in 1 month from 0.34 to 2.48%. No RB1 mutations were detected in the cfDNA from plasma of patients with simulating lesions (3 Coats and 1 PFV). In 2 cases, we identified two independent RB1 mutations in plasma. Conclusions Mutations in RB1 were found in the cfDNA from blood of newly diagnosed, untreated retinoblastoma patients and in patients who recurred in the eye after treatment but not in unilateral retinoblastoma after enucleation Levels of ctDNA increase in patients with progressive disease who did not receive any treatment. High plasma cfDNA levels were detected in patients with newly diagnosed metastatic disease and these levels decreased after systemic chemotherapy was given. Further validation is needed for measuring the somatic alterations in cell free DNA from blood in retinoblastoma that could provide a promising method of monitoring patients in the future.