Cell-free RB1 DNA not detected in the blood of pseudoretinoblastoma patients

Cell-free DNA (cfDNA) is commonly found in the blood (plasma) of patients with cancer. When analysing cfDNA for a specific cancer-causing mutation, it is referred to as ctDNA. RB1 ctDNA is commonly present in the blood of retinoblastoma patients. We examined RB1 ctDNA from blood of 40 children with retinoblastoma look alike lesions (‘pseudoretinoblastoma’) to determine if any RB1 abnormalities could be identified. OBJECTIVES: Because retinoblastoma diagnosis is usually made with the indirect ophthalmoscope without biopsy clinical errors continue to occur worldwide. Because cf RB1 is detectible in plasma of children with retinoblastoma, we wondered if it was present in the blood of pseudoretinoblastomas with the hope of ultimately developing a blood based test to aid clinicians in the diagnosis of retinoblastoma. The goal of this project was to see if circulating plasma RB1 cfDNA could be detected in the blood of patients with pseudoretinoblastoma. METHODS AND ANALYSIS: Plasma cfDNA for circulating RB1 cfDNA was assayed with MSKCC’s next generation sequencing, N.Y. State Approved assay called ACCESS to evaluate somaticmutations in 40 patients with pseudoretinoblastoma. RESULTS: No plasma cfDNA RB1 was detected in the blood (plasma) of 40 patients with pseudoretinoblastoma. CONCLUSION: Plasma cfDNA RB1 is commonly detectible in retinoblastoma patients but not in patients with a diverse group of pseudoretinoblastomas.