Targeted therapies in retinoblastoma: GD2-directed immunotherapy following autologous stem cell transplantation and evaluation of alternative target B7-H3.

BACKGROUND: GD2-directed immunotherapy is highly effective in the treatment of high-risk neuroblastoma (NB), and might be an interesting target also in other high-risk tumors. METHODS: The German-Austrian Retinoblastoma Registry, Essen, was searched for patients, who were treated with anti-GD2 monoclonal antibody (mAb) dinutuximab beta (Db) in order to evaluate toxicity, response and outcome in these patients. Additionally, we evaluated anti-GD2 antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) in retinoblastoma cell lines in vitro. Furthermore, in vitro cytotoxicity assays directed against B7-H3 (CD276), a new identified potential target in RB, were performed. RESULTS: We identified four patients with relapsed stage IV retinoblastoma, who were treated with Db following autologous stem cell transplantation (ASCT). Two out of two evaluable patients with detectable tumors responded to immunotherapy. One of these and another patient who received immunotherapy without residual disease relapsed 10 and 12 months after start of Db. The other patients remained in remission until last follow-up 26 and 45 months, respectively. In vitro, significant lysis of RB cell lines by ADCC and CDC with samples from patients and healthy donors and anti-GD2 and anti-CD276-mAbs were demonstrated. CONCLUSION: Anti-GD2-directed immunotherapy represents an additional therapeutic option in high-risk metastasized RB. Moreover, CD276 is another target of interest.

Optic nerve thickening on high-spatial-resolution MRI predicts early-stage postlaminar optic nerve invasion in retinoblastoma.

OBJECTIVES: To assess the diagnostic accuracy of nerve thickening on MRI to predict early-stage postlaminar optic nerve invasion (PLONI) in retinoblastoma. Furthermore, this study aimed to incorporate measurements into a multiparametric model for radiological determination of PLONI. METHODS: In this retrospective multicenter case-control study, high-spatial-resolution 3D T2-weighted MR images were used to measure the distal optic nerve. Histopathology was the reference standard for PLONI. Two neuroradiologists independently measured the optic nerve width, height, and surface at 0, 3, and 5 mm from the most distal part of the optic nerve. Subsequently, PLONI was scored on contrast-enhanced T1-weighted and 3D T2-weighted images, blinded for clinical data. Optic nerve measurements with the highest diagnostic accuracy for PLONI were incorporated into a prediction model for radiological determination of PLONI. RESULTS: One hundred twenty-four retinoblastoma patients (median age, 22 months [range, 0-113], 58 female) were included, resulting in 25 retinoblastoma eyes with histopathologically proven PLONI and 206 without PLONI. ROC analysis of axial optic nerve width measured at 0 mm yielded the best area under the curve of 0.88 (95% confidence interval: 0.79, 0.96; p < 0.001). The optimal width cutoff was ≥ 2.215 mm, with a sensitivity of 84% (95% CI: 64, 95%) and specificity of 83% (95% CI: 75, 89%) for detecting PLONI. Combining width measurements with the suspicion of PLONI on MRI sequences resulted in a prediction model with an improved sensitivity and specificity of respectively up to 88% and 92%. CONCLUSION: Postlaminar optic nerve thickening can predict early-stage postlaminar optic nerve invasion in retinoblastoma. CLINICAL RELEVANCE STATEMENT: This study provides an additional tool for clinicians to help determine postlaminar optic nerve invasion, which is a risk factor for developing metastatic disease in retinoblastoma patients. KEY POINTS: • The diagnostic accuracy of contrast-enhanced MRI for detecting postlaminar optic nerve invasion is limited in retinoblastoma patients. • Optic nerve thickening can predict postlaminar optic nerve invasion. • A prediction model combining MRI features has a high sensitivity and specificity for detecting postlaminar optic nerve invasion.

Preoperative Detection of Local Tumor Extent in Patients with Advanced Retinoblastoma: Predictive Value of MRI and Clinical Findings. / Präoperativer Nachweis der lokalen Tumorausdehnung bei Patienten mit fortgeschrittenem Retinoblastom: prädiktiver Wert MR-tomografischer und klinischer Befunde.

OBJECTIVE: Before planned enucleation, local tumor extension in advanced retinoblastoma is routinely assessed preoperatively using high-resolution magnetic resonance imaging (MRI). The aim of our study was to analyse the predictive value of MRI and clinical characteristics for predicting tumor extent, as confirmed by histopathology postoperatively. PATIENTS AND METHODS: All consecutive patients were included who underwent primary enucleation for advanced retinoblastoma after high-resolution MRI examination in our hospital between January 2011 and December 2021. The primary study endpoint was the evaluation of the predictability of histopathological risk factors on preoperative MRI examination. The sensitivity and specificity of the MRI examination with respect to clinically relevant optic nerve infiltration and choroidal infiltration were determined. RESULTS: The mean age of the 209 included patients was 1.6 years (range 1 month to 4.7 years). MRI indicated optic nerve infiltration in 46 (22%) patients, extensive choroidal infiltration in 78 (40.2%) patients, and scleral infiltration in one patient (2.6%). Histopathological examination demonstrated postlaminar optic infiltration in 25 (12%) patients and extensive choroidal infiltration in 17 (8.1%) cases. Scleral infiltration was evident in 8 (3.8%) patients. In the final multivariate analysis, MRI findings of tumor infiltration and a preoperative intraocular pressure ≥ 20 mmHg were independently associated with histopathological evidence of clinically relevant optic nerve (p = 0.033/p = 0.011) and choroidal infiltration (p = 0.005/p = 0.029). The diagnostic accuracy of the prediction models based on the multivariate analysis for the identification of the clinically relevant optic nerve (AUC = 0.755) and choroidal infiltration (AUC = 0.798) was greater than that of purely MRI-based prediction (respectively 0.659 and 0.742). The sensitivity and specificity of MRI examination for determining histopathological risk factors in our cohort were 64% and 65% for clinically relevant optic infiltration and 87% and 64% for clinically relevant choroidal infiltration. CONCLUSION: The local tumor extent of retinoblastoma with infiltration of the optic nerve and choroid can be well estimated based on radiological and clinical characteristics before treatment initiation. The combination of clinical and radiological risk factors supports the possibility of early treatment stratification in retinoblastoma patients.

PDGF, NGF, and EGF as main contributors to tumorigenesis in high-risk retinoblastoma.

Retinoblastoma (RB) is the most common form of eye cancer experienced in childhood. Its aggressive malignancy is associated with excellent survival rates in high-income countries; however, the prognosis in third-world countries is less favorable. Early diagnosis can maximize the patient's visual outcomes and their survival rate. Therapy should be conducted in highly specialized treatment centers. Intravenous chemotherapy (IVC) in bilaterally affected children currently forms the majority of therapy. Local destructive procedures and local chemotherapies such as intra-arterial chemotherapy (IAC) or intravitreal chemotherapy can be taken into consideration depending on the extent and size of the tumor. Nonetheless, children and parents remain under constant stress, revisiting doctors for medical treatment and fearing vision loss and even enucleation of the eye. Adequate molecular patient stratification to improve targeted therapy is still lacking. This retrospective study analyzed formalin-fixed paraffin-embedded specimens from a cohort of 21 RB samples. A total of 11 of those samples showed undifferentiated retinoblastoma (URB) histopathological risk features, and the other 10 showed differentiated retinoblastoma (DRB) histopathological grading. RNA from all samples was isolated and analyzed via digital gene expression patterns. Conductors of cell survival and DNA repair were dominant in the DRB samples. In contrast, the agents responsible for cell-cycle progression and apoptosis were overexpressed in URB samples. Our work reveals the importance of molecular mechanisms within the immune system subjected to histologic subtypes of RB, providing more detailed background on their genetic behavior. This is of great interest for therapeutic strategies, such as targeted immune- and gene-based therapies, for retinoblastoma.

Zebrafish as an Orthotopic Tumor Model for Retinoblastoma Mimicking Routes of Human Metastasis.

BACKGROUND: Retinoblastoma (RB) is the most common eye cancer in children that has a high mortality rate when left untreated. Mouse models for retinoblastoma have been established but are time- and cost-intensive. The aim of this work was to evaluate an orthotopic transplantation model of retinoblastoma in zebrafish that also allows for tracking migratory routes and to explore advantages and disadvantages with respect to drug testing. METHODS: Three fluorescence-labeled retinoblastoma cell lines (RB355, WERI-RB-1, Y79) were injected into the left eye of two-day-old zebrafish, while the un-injected right eye served as control. The migratory trajectories of injected retinoblastoma cells were observed until 8 days post injection (dpi), both in lateral and dorsal view, and measuring fluorescence intensity of injected cells was done for RB355 cells. RESULTS: Time until the onset of migration and routes for all three retinoblastoma cell lines were comparable and resulted in migration into the brain and ventricles of the forebrain, midbrain and hindbrain. Involvement of the optic nerve was observed in 10% of injections with the RB355 cell line, 15% with Y79 cells and 5% with WERI-RB-1 cells. Fluorescence intensity of injected RB355 cells showed an initial increase until five dpi, but then decreased with high variability until the end of observation. CONCLUSION: The zebrafish eye is well suited for the analysis of migratory routes in retinoblastoma and closely mirrors patterns of retinoblastoma metastases in humans.

[Imaging of retinoblastoma : Current state-of-the-art and future prospects]. / Bildgebung des Retinoblastoms : Aktueller Stand der Technik und Ausblick in die Zukunft.

BACKGROUND: Retinoblastoma is the most common malignant eye tumor in children and is associated with tumor predisposition syndrome (RB1 mutation) in up to 40% of cases. Imaging is an important part of the diagnostic workup of children with retinoblastoma both during the initial diagnosis and follow-up. OBJECTIVES: The goal of this review is to present the current state-of-the-art regarding imaging of children with retinoblastoma, including technical background and diagnostic clues with a brief discussion of future prospects. In addition, we summarize the general clinical diagnostic workup and therapeutic options. MATERIALS AND METHODS: Review of the literature and our own experience in the imaging of retinoblastoma. CONCLUSION: High-resolution magnetic resonance imaging (MRI) is the imaging modality of choice in children with retinoblastoma for diagnosis (estimation of diagnosis/differential diagnosis, evaluation of local and intracranial tumor extension) and during follow-up. Despite the characteristic calcifications, computed tomography (CT) examinations are no longer indicated in these patients. Due to the high association with tumor predisposition syndrome, genetic counselling is recommended.

Gain and loss of TASK3 channel function and its regulation by novel variation cause KCNK9 imprinting syndrome.

BACKGROUND: Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for KCNK9 imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood. METHODS: This study discovers mechanisms underlying KCNK9 imprinting syndrome (KIS) by describing 15 novel KCNK9 alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies. RESULTS: We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of KCNK9 variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of KCNK9 genetic variants, however, was altered channel regulation. CONCLUSIONS: This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of KCNK9 variation on channel function and regulation.

Combination of Brachytherapy and Intravitreal Chemotherapy in the Treatment of Retinoblastoma with Vitreous Seeding.

Purpose: The aim of this study was to report the efficacy of combined intravitreal chemotherapy (IVC) and ruthenium-106 brachytherapy in retinoblastoma, either as first-line or second-line treatment, following systemic chemoreduction or intra-arterial chemotherapy. Methods: Retrospective data of 18 eyes from 18 patients treated with IVC and brachytherapy from August 2014 to December 2019 were collected. Results: The method described was our first-line therapy in 6 patients, whereas it was used as second-line treatment after chemoreduction in the remaining 12 patients. The eyes showed the following classification at initial presentation: 2 group B eyes, 3 group C eyes, and 13 group D eyes. The mean follow-up was 19.5 months (range 2-53 months). The mean patient age at brachytherapy was 34.0 months (range 15-83 months). The median prescribed dose at the tumour base and apex was 574.5 ± 306.7 Gy and 88.5 ± 12.2 Gy, respectively. The ocular retention rate was 66.7%. Six eyes had to be enucleated due to uncontrollable subretinal and recurrent vitreous seeding, tumour relapse, recurrence of a solid tumour elsewhere in the eye, and persistent vitreous bleeding with loss of tumour control. The mean number of intravitreal injections of melphalan was 5.0. Two patients received a simultaneous injection of topotecan for insufficient therapeutic response. With regard to radiogenic complications, we could observe temporary retinal and vitreous bleeding (27.8%), serous retinal detachment (44.4%), and radiogenic maculopathy and retinopathy (11.1%). None of the children showed metastatic disease during follow-up. Conclusion: Ruthenium-106 plaque therapy in combination with IVC is an effective local therapy with good tumour control rates even in advanced eyes. Overall, the analysed therapeutic approach shows an acceptable side-effect profile, especially when considering that external-beam radiation therapy and systemic polychemotherapy or at least the number of cycles needed, with their increased incidence of adverse events, can thus be avoided.

Long-Term Results after Intraocular Surgery in Treated Retinoblastoma Eyes.

Introduction: The aim of the study was to analyze the results of intraocular surgery in treated retinoblastoma eyes and to assess the long-term results with a priority on local recurrences, secondary enucleation, and metastases. Methods: Retrospective noncomparative case series. Results: From March 1964 to January 2020, 42 eyes of 40 retinoblastoma patients underwent intraocular surgery. Time interval between the last therapy and surgery was 9.5 years (mean: 114 months; median: 54.5 months). 31 eyes were treated for radiogenic cataract formation with a gain in visual acuity of 61.3%. One child developed an upper eyelid metastasis, 3 showed second primary malignancies (SPM), one a late recurrence, and 2 eyes were enucleated. Retinal surgery was performed in 17 eyes; 6 eyes were done as a combined procedure. Indications were radiogenic complications in the sense of a vitreous hemorrhage in 11 eyes and a rhegmatogenous retinal detachment in 6 eyes. 41.2% of the treated eyes had a postoperative gain in visual acuity, whereas 9.5% of the eyes could not be preserved in the long term. Regarding systemic involvement 2 patients developed late recurrences and one a SPM. Conclusion: Surgical therapy in treated retinoblastoma is necessary in isolated cases. In our series, cataract surgery was a safe procedure with a good option of a significant increase in visual acuity. As expected, vitreoretinal treated eyes showed a limited gain in visual acuity, a higher risk of late recurrences, and a lower globe retention rate. Therefore, a careful indication and individual risk-benefit analysis are mandatory.

Comparing efficacy and side effects of two systemic chemotherapy regimens for eye-preserving therapy in children with retinoblastoma.

BACKGROUND: Eye-preserving therapy in retinoblastoma comprises systemic chemotherapy, but studies analyzing the efficacy of different chemotherapy regimens are scarce. METHODS: The efficacy and side effects of two different eye-preserving chemotherapy regimens containing either vincristine, etoposide, and carboplatin (VEC) or cyclophosphamide, vincristine, etoposide, and carboplatin (CyVEC) were compared in a prospective non-interventional observational study including children diagnosed with retinoblastoma between 2013 and 2019 in Germany and Austria. Event-free eye survival (EFES) and overall eye survival (OES) of all 164 eyes treated with both regimens and risk factors were investigated. RESULTS: The EFES after VEC (2-year EFES 72.3%) was higher than after CyVEC (2-year EFES 50.4%) (plogrank  < .001). The OES did not differ significantly between the two treatment groups (plogrank  = .77; 2-year OES VEC: 82.1% vs. CyVEC: 84.8%). Advanced International Classification of Retinoblastoma (ICRB) group was prognostic for a lower EFES (plogrank  < .0001; 2-year EFES ICRB A/B/C 71.3% vs. ICRB D/E 43.0%) and OES (plogrank  < .0001; 2-year OES ICRB A/B/C 93.1% vs. ICRB D/E 61.5%). The multivariate analysis showed that age at diagnosis older than 12 months and ICRB A/B/C were associated with better EFES. No second malignancies or ototoxicities were reported after a follow-up of median 3.1 years after diagnosis of retinoblastoma (range 0.1-6.9 years). CONCLUSIONS: Despite omitting cyclophosphamide, the EFES was higher after VEC chemotherapy that contains higher doses of carboplatin compared to CyVEC. The major risk factor for enucleation was advanced ICRB tumor grouping. Randomized clinical trials on efficacy and side effects of eye-preserving chemotherapy are required to tailor treatment protocols for retinoblastoma patients.

The Pediatric Precision Oncology INFORM Registry: Clinical Outcome and Benefit for Patients with Very High-Evidence Targets.

INFORM is a prospective, multinational registry gathering clinical and molecular data of relapsed, progressive, or high-risk pediatric patients with cancer. This report describes long-term follow-up of 519 patients in whom molecular alterations were evaluated according to a predefined seven-scale target prioritization algorithm. Mean turnaround time from sample receipt to report was 25.4 days. The highest target priority level was observed in 42 patients (8.1%). Of these, 20 patients received matched targeted treatment with a median progression-free survival of 204 days [95% confidence interval (CI), 99-not applicable], compared with 117 days (95% CI, 106-143; P = 0.011) in all other patients. The respective molecular targets were shown to be predictive for matched treatment response and not prognostic surrogates for improved outcome. Hereditary cancer predisposition syndromes were identified in 7.5% of patients, half of which were newly identified through the study. Integrated molecular analyses resulted in a change or refinement of diagnoses in 8.2% of cases. SIGNIFICANCE: The pediatric precision oncology INFORM registry prospectively tested a target prioritization algorithm in a real-world, multinational setting and identified subgroups of patients benefiting from matched targeted treatment with improved progression-free survival, refinement of diagnosis, and identification of hereditary cancer predisposition syndromes.See related commentary by Eggermont et al., p. 2677.This article is highlighted in the In This Issue feature, p. 2659.

Intraarterial Chemotherapy for Retinoblastoma - Initial Experiences of a German Reference Centre. / Intraarterielle Chemotherapie beim Retinoblastom ­ erste Erfahrungen eines deutschen Referenzzentrums.

BACKGROUND: Adequate management of retinoblastoma requires a multidisciplinary and individual approach to treatment. Intraarterial chemotherapy (IAC) is one of the most commonly used treatment modalities, and enables supraselective application of chemotherapy via the ophthalmic artery and is now established in almost all treatment centres. However, published treatment success rates are heterogeneous. There are some unanswered issues regarding sight-threatening ocular complications and the long-term occurrence of secondary malignancies and metastatic disease. The objective of the present study is to analyse the results of a German national reference centre. METHODS: Retrospective analysis of all children with an indication for at least one IAC from April 2010 to April 2020. IAC was used either as primary or recurrence therapy. Obligatory follow-up was at least 6 months. RESULTS: 137 eyes of 127 children with an indication for IAC could be included. 12 eyes with a follow-up of less than 6 months and 37 eyes in which IAC was technically not feasible were excluded. In summary, 88 eyes of 79 children were finally analysed. Mean follow-up was 38 months, ranging from 7 to 117 months. In total, 195 procedures were completed. In 30 eyes (34.1%) IAC was conducted as primary and in 58 (65.9%) as secondary therapy. There was an initial IAC treatment response in 75 eyes (85.2%) with a recurrence-free rate of 61.3%. Eye salvage rate was 68.1% with 28 enucleated eyes in total. Ocular complications were observed in 36 eyes (40.9%), with 19 eyes (21.6%) showing severe sight-threatening and 11 eyes (12.5%) presenting minor non-sight-threatening toxic reactions. During follow-up, 1 child developed a secondary malignancy, 1 child developed metastasis and 1 child died as a consequence of trilateral retinoblastoma. CONCLUSION: In summary, IAC is a potent modality for retinoblastoma treatment and has been very successful, even in advanced disease and heavily pretreated eyes. However, ocular complications should be taken in consideration, especially when the only seeing eye is treated. Long term incidences of secondary malignancies and metastatic diseases should be further investigated in prospective studies.

Eye Tumors in Childhood as First Sign of Tumor Predisposition Syndromes: Insights from an Observational Study Conducted in Germany and Austria.

Retinoblastoma and other eye tumors in childhood are rare diseases. Many eye tumors are the first signs of a genetic tumor predisposition syndrome and the affected children carry a higher risk of developing other cancers later in life. Clinical and genetic data of all children with eye tumors diagnosed between 2013-2018 in Germany and Austria were collected in a multicenter prospective observational study. In five years, 300 children were recruited into the study: 287 with retinoblastoma, 7 uveal melanoma, 3 ciliary body medulloepithelioma, 2 retinal astrocytoma, 1 meningioma of the optic nerve extending into the eye. Heritable retinoblastoma was diagnosed in 44% of children with retinoblastoma. One child with meningioma of the optic nerve extending into the eye was diagnosed with neurofibromatosis 2. No pathogenic constitutional variant in DICER1 was detected in a child with medulloepithelioma while two children did not receive genetic analysis. Because of the known association with tumor predisposition syndromes, genetic counseling should be offered to all children with eye tumors. Children with a genetic predisposition to cancer should receive a tailored surveillance including detailed history, physical examinations and, if indicated, imaging to screen for other cancer. Early detection of cancers may reduce mortality.

Feasibility of Proton Beam Therapy as a Rescue Therapy in Heavily Pre-Treated Retinoblastoma Eyes.

Despite the increased risk of subsequent primary tumors (SPTs) external beam radiation (EBRT) may be the only therapeutic option to preserve a retinoblastoma eye. Due to their physical properties, proton beam therapy (PBT) offers the possibility to use the effectiveness of EBRT in tumor treatment and to decisively reduce the treatment-related morbidity. We report our experiences of PBT as rescue therapy in a retrospectively studied cohort of 15 advanced retinoblastoma eyes as final option for eye-preserving therapy. The average age at the initiation of PBT was 35 (14-97) months, mean follow-up was 22 (2-46) months. Prior to PBT, all eyes were treated with systemic chemotherapy and a mean number of 7.1 additional treatments. Indication for PBT was non-feasibility of intra-arterial chemotherapy (IAC) in 10 eyes, tumor recurrence after IAC in another 3 eyes and diffuse infiltrating retinoblastoma in 2 eyes. Six eyes (40%) were enucleated after a mean time interval of 4.8 (1-8) months. Cataract formation was the most common complication affecting 44.4% of the preserved eyes, yet 77.8% achieved a visual acuity of >20/200. Two of the 15 children treated developed metastatic disease during follow-up, resulting in a 13.3% metastasis rate. PBT is a useful treatment modality as a rescue therapy in retinoblastoma eyes with an eye-preserving rate of 60%. As patients are at lifetime risk of SPTs consistent monitoring is mandatory.

Introduction of a Variant Classification System for Analysis of Genotype-Phenotype Relationships in Heritable Retinoblastoma.

Constitutional haploinsufficiency of the RB1 gene causes heritable retinoblastoma, a tumor predisposition syndrome. Patients with heritable retinoblastoma develop multiple retinoblastomas early in childhood and other extraocular tumors later in life. Constitutional pathogenic variants in RB1 are heterogeneous, and a few genotype-phenotype correlations have been described. To identify further genotype-phenotype relationships, we developed the retinoblastoma variant effect classification (REC), which considers each variant's predicted effects on the common causal mediator, RB1 protein pRB. For validation, the RB1 variants of 287 patients were grouped according to REC. Multiple aspects of phenotypic expression were analyzed, known genotype-phenotype associations were revised, and new relationships were explored. Phenotypic expression of patients with REC-I, -II, and -III was distinct. Remarkably, the phenotype of patients with variants causing residual amounts of truncated pRB (REC-I) was more severe than patients with complete loss of RB1 (REC-II). The age of diagnosis of REC-I variants appeared to be distinct depending on truncation's localization relative to pRB structure domains. REC classes identify genotype-phenotype relationships and, therefore, this classification framework may serve as a tool to develop tailored tumor screening programs depending on the type of RB1 variant.

Adjuvant therapy of histopathological risk factors of retinoblastoma in Europe: A survey by the European Retinoblastoma Group (EURbG).

INTRODUCTION: Advanced intraocular retinoblastoma can be cured by enucleation, but spread of retinoblastoma cells beyond the natural limits of the eye is related to a high mortality. Adjuvant therapy after enucleation has been shown to prevent metastasis in children with risk factors for extraocular retinoblastoma. However, histological criteria and adjuvant treatment regimens vary and there is no unifying consensus on the optimal choice of treatment. METHOD: Data on guidelines for adjuvant treatment in European retinoblastoma referral centres were collected in an online survey among all members of the European Retinoblastoma Group (EURbG) network. Extended information was gathered via personal email communication. RESULTS: Data were collected from 26 centres in 17 countries. Guidelines for adjuvant treatment were in place at 92.3% of retinoblastoma centres. There was a consensus on indication for and intensity of adjuvant treatment among more than 80% of all centres. The majority of centres use no adjuvant treatment for isolated focal choroidal invasion or prelaminar optic nerve invasion. Patients with massive choroidal invasion or postlaminar optic nerve invasion receive adjuvant chemotherapy, while microscopic invasion of the resection margin of the optic nerve or extension through the sclera are treated with combined chemo- and radiotherapy. CONCLUSION: Indications and adjuvant treatment regimens in European retinoblastoma referral centres are similar but not uniform. Further biomarkers in addition to histopathological risk factors could improve treatment stratification. The high consensus in European centres is an excellent foundation for a common European study with prospective validation of new biomarkers.

Estimation of radiation exposure of children undergoing superselective intra-arterial chemotherapy for retinoblastoma treatment: assessment of local diagnostic reference levels as a function of age, sex, and interventional success.

PURPOSE: This study aims to determine local diagnostic reference levels (LDRLs) of intra-arterial chemotherapy (IAC) procedures of pediatric patients with retinoblastoma (RB) to provide data for establishing diagnostic reference levels (DRLs) in pediatric interventional radiology (IR). METHODS: In a retrospective study design, LDRLs and achievable dose (AD) were assessed for children undergoing superselective IAC for RB treatment. All procedures were performed at the flat-panel angiography systems (I) ArtisQ biplane (Siemens Healthineers) and (II) Allura Xper (Philips Healthcare). Patients were differentiated according to age (A1: 1-3 months; A2: 4-12 months; A3: 13-72 months; A4: 73 months-10 years; A5: > 10 years), sex, conducted or not-conducted chemotherapy. RESULTS: 248 neurointerventional procedures of 130 pediatric patients (median age 14.5 months, range 5-127 months) with RB (68 unilateral, 62 bilateral) could be included between January 2010 and March 2020. The following diagnostic reference values, AD, and mean values could be determined: (A2) DRL 3.9 Gy cm2, AD 2.9 Gy cm2, mean 3.5 Gy cm2; (A3) DRL 7.0 Gy cm2, AD 4.3 Gy cm2, mean 6.0 Gy cm2; (A4) DRL 14.5 Gy cm2, AD 10.7 Gy cm2, mean 10.8 Gy cm2; (A5) AD 8.8 Gy cm2, mean 8.8 Gy cm2. Kruskal-Wallis-test confirmed a significant dose difference between the examined age groups (A2-A5) (p < 0.001). There was no statistical difference considering sex (p = 0.076) and conducted or not-conducted chemotherapy (p = 0.627). A successful procedure was achieved in 207/248 cases. CONCLUSION: We report on radiation exposure during superselective IAC of a pediatric cohort at the German Retinoblastoma Referral Centre. Although an IAC formally represents a therapeutic procedure, our results confirm that radiation exposure lies within the exposure of a diagnostic interventional procedure. DRLs for superselective IAC are substantially lower compared with DRLs of more complex endovascular interventions.

Long-Term Clinical Results and Management following Vitrectomy in Undetected Retinoblastoma Eyes.

INTRODUCTION: Given the rarity of retinoblastoma and the consequences of accidental vitrectomy in the event of misdiagnosis, reporting on clinical experience in this area is important. OBJECTIVE: The aim of this study was to analyse the management and complications with a focus on local orbital recurrence and metastatic disease in 10 children vitrectomized in an undetected retinoblastoma eye. METHODS: This is a retrospective descriptive case series conducted in a single-centre referral university hospital. RESULTS: From October 1991 to June 2019, 10 patients with a vitrectomy in an unsuspected retinoblastoma eye were included in this study. The main preoperative diagnoses were unilateral inflammation with a suspected lymphoma, uveitis or toxocariasis in 5 cases, vitreous haemorrhage after trauma in 2 cases, and the last 3 were misdiagnosed with Coats disease, rhegmatogenous retinal detachment and congenital cataract. Mean age at surgery was 3 years, ranging from 14 months to 6 and a half years. Nine patients were suffering from unilateral retinoblastoma; these were enucleated and treated with 4-6 cycles of chemotherapy and/or radiation therapy. The sclerotomy sites were infiltrated with tumour cells in 3 cases. In 1 patient, the differential diagnosis of a malignant medulloepithelioma could not be excluded. One patient had bone marrow infiltration on initial presentation; all other patients are healthy without any signs of orbital recurrence or metastatic disease with a mean follow-up of 5.4 years. CONCLUSION: In children, intraocular tumours, including retinoblastoma and medulloepithelioma, should be ruled out before pars plana vitrectomy is performed. If no doubtless preoperative diagnosis can be established, preoperative magnetic resonance imaging is mandatory. If a vitrectomy in a retinoblastoma eye has been performed, immediate enucleation of the eye with subsequent chemotherapy and orbital radiation is effective to avoid local recurrence and systemic metastases.

13q deletion syndrome resulting from balanced chromosomal rearrangement in father: the significance of parental karyotyping.

BACKGROUND: Retinoblastoma is a malignancy of the eye in children characterized by biallelic inactivation of the retinoblastoma 1 gene (RB1), located at chromosome 13q14.2. Children with interstitial chromosome 13q deletions that include the RB1 gene show a predisposition to develop retinoblastoma and variable other features. Large 13q deletions with severe clinical phenotype are nearly always the result of a de novo mutation, i.e. the pathogenic alteration is not detected in parents. This results in a low risk for siblings to develop 13q deletion syndrome. RESULT: Here, we describe a patient with profound muscle hypotonia, severe developmental delay and bilateral retinoblastoma carrying a large deletion in 13q13.3q14 with the size of 16 Mb, involving the RB1 gene. Neither parent showed retinoblastoma, muscle hypotonia or developmental delay. Chromosome analysis and Fluorescence in situ hybridization (FISH) showed a balanced complex chromosomal rearrangement (CCR) between chromosome 12 and 13 [ins(12;13)(q21.2;q12.3q14.3)] and an additional balanced translocation of chromosome 7 and 15 [t(7;15)(q31.2;q25.3)] in the healthy father. Malsegregation of the paternal insertional translocation involving chromosome 12 and 13 resulted in a 13q deletion syndrome of the child [46,XY,ins(12;13)(q21.2;q12.3q14.3)]. CONCLUSION: Balanced translocations in parents are a rare cause of de novo RB1 deletions in offspring. This case report emphasizes the need for parental chromosomal analysis and FISH in parents of children diagnosed with 13q deletion syndrome or large RB1 gene deletions to precisely determine the recurrence risk in siblings. Guidelines for genetic testing should be revised accordingly.

Bone metastasis of retinoblastoma five years after primary treatment.

PURPOSE: Histopathological, immunohistochemistry- and molecular pathology-based diagnostics to distinguish metastasis of retinoblastoma from subsequent primary malignancy in patients with heritable retinoblastoma. OBSERVATIONS: An eight year-old girl presented with tibial pain and bone lesion five years after multimodal treatment of bilateral retinoblastoma, initially clinically suspicious of osteomyelitis. Histopathological examination of bone biopsy specimen revealed a highly proliferative small blue round cell tumor mimicking Ewing's sarcoma of bone. Immunohistochemistry confirmed the diagnosis of a distant metastasis of the previous retinoblastoma. Other subsequent primary malignancies presenting as small blue round cell tumors, such as sarcomas or leukemia, were excluded by immunohistochemistry and molecular methods. CONCLUSIONS AND IMPORTANCE: In countries with early diagnosis of retinoblastoma, distant metastases of retinoblastoma are extremely rare, whereas subsequent primary malignancies are common in survivors of heritable retinoblastoma. Immunohistochemistry and molecular pathology are essential components of diagnostic pathway. In retinoblastoma patients, distant metastases including osseous lesions should be included in the differential diagnosis of small blue round cell tumors.