Next-generation sequencing-based method shows increased mutation detection sensitivity in an Indian retinoblastoma cohort.

PURPOSE: Retinoblastoma (Rb) is the most common primary intraocular cancer of childhood and one of the major causes of blindness in children. India has the highest number of patients with Rb in the world. Mutations in the RB1 gene are the primary cause of Rb, and heterogeneous mutations are distributed throughout the entire length of the gene. Therefore, genetic testing requires screening of the entire gene, which by conventional sequencing is time consuming and expensive. METHODS: In this study, we screened the RB1 gene in the DNA isolated from blood or saliva samples of 50 unrelated patients with Rb using the TruSight Cancer panel. Next-generation sequencing (NGS) was done on the Illumina MiSeq platform. Genetic variations were identified using the Strand NGS software and interpreted using the StrandOmics platform. RESULTS: We were able to detect germline pathogenic mutations in 66% (33/50) of the cases, 12 of which were novel. We were able to detect all types of mutations, including missense, nonsense, splice site, indel, and structural variants. When we considered bilateral Rb cases only, the mutation detection rate increased to 100% (22/22). In unilateral Rb cases, the mutation detection rate was 30% (6/20). CONCLUSIONS: Our study suggests that NGS-based approaches increase the sensitivity of mutation detection in the RB1 gene, making it fast and cost-effective compared to the conventional tests performed in a reflex-testing mode.

Periocular topotecan for intraocular retinoblastoma.

OBJECTIVE: To review the effectiveness and toxicity of periocular topotecan hydrochloride in fibrin sealant (Tisseel) for the control of intraocular retinoblastoma. METHODS: Retrospective medical record review of visually threatening or recurrent intraocular retinoblastoma treated with periocular topotecan. RESULTS: Eight children (10 eyes) received 1 to 4 injections of periocular topotecan in fibrin sealant, without or with concomitant laser and/or single freeze-thaw prechemotherapy cryotherapy. Median dose was 0.18 mg/kg (3.72 mg/m(2)). The 6 children who responded to treatment had small discrete tumors (8 International Intraocular Retinoblastoma Classification group A or B eyes). Of these, prior primary treatment for 3 children (3 eyes) was laser; for 1 child (2 eyes), systemic chemotherapy with focal laser; and for 2 children (3 eyes), periocular topotecan. In 4 children (4 eyes), tumor regression was sufficient for effective focal therapy, but in 2 children (4 eyes), long-term control required systemic chemotherapy. The 2 children who did not respond each had an International Intraocular Retinoblastoma Classification group D eye treated primarily with systemic chemotherapy, focal laser, and cryotherapy and recurrent disease that was not controlled by periocular topotecan; both eyes were eventually enucleated. No ocular and minimal hematological toxic effects were observed. At 11 months' median follow-up after topotecan treatment (18 months since diagnosis), all 8 group A and B eyes were retained with ongoing focal therapy required in only 1 group B eye; the 2 group D eyes were enucleated. CONCLUSION: Periocular topotecan in fibrin sealant can achieve volume reduction of small and recurrent retinoblastoma sufficient to allow successful focal therapy.

Management and outcome of unilateral retinoblastoma.

BACKGROUND: Two-thirds of retinoblastoma cases are unilateral, with most presenting with an advanced stage of disease. Primary enucleation is usually the preferred treatment. Conservative therapy may save less involved eyes. METHODS: We retrospectively reviewed the presentation, age at diagnosis, classification, genetic status, treatment, and long-term outcome of 130 patients with unilateral retinoblastoma (1988-2008). RESULTS: The mean age at presentation was 26 months. Based on retinoblastoma gene (RB1) status in tumors, germ-line status was defined in 92% of patients; 13% had a germ-line mutation. The primary treatment of 106 patients was enucleation. Severe disease at presentation (International Intraocular Retinoblastoma Classification [IIRC] group E) was significantly (p < 0.001) associated with adverse histopathological risk factors. Of the 16 patients who underwent eye-conserving therapy, treatment was successful in 9 (IIRC group A, 1; B, 5; C, 3). Two patients with a pertinent family history were diagnosed early and were treated solely with focal therapy. Three patients retained vision of 6/18 or better in the treated eye (median follow-up, 33 months; range, 2-120 months). Seven patients (IIRC group: B, 2; C, 4; D, 1) eventually underwent enucleation. One patient died of metastases following delayed parental consent for enucleation and refusal of prophylactic chemotherapy for high-risk histopathologic features. CONCLUSIONS: Chemotherapy/focal therapy can save selected eyes, but primary enucleation is preferred for advanced unilateral retinoblastoma. "Conservative" treatment is an option when there is good potential for useful vision without prolonged, costly therapy with potential side effects. Simple enucleation reduces the risk of masking high-risk pathology and promotes early return to normal life.