Not All Seeds Are Created Equal: Seed Classification Is Predictive of Outcomes in Retinoblastoma

Safety of intravitreal chemotherapy in the management of retinoblastoma: A systematic review of the literature

Intravitreal chemotherapy is used as a salvage therapy for retinoblastoma with persistent or recurrent vitreous seeding after primary treatment. To assess the safety of this technique, we conducted a systematic review of all studies reporting ocular toxicity data. Forty-eight trials involving 2751 eyes were included. The most common complications were cataract, retinal toxicity, and vitreous hemorrhage. However, severe and permanent adverse events were limited, while the risk of extraocular dissemination, a significant concern, was practically eliminated through preventive techniques. Globe salvage rates ranged from 29 % to 100 %. In conclusion, intravitreal chemotherapy seems to improve prognosis of eyes with advanced disease, with an acceptable safety profile. Nevertheless, most relevant studies are retrospective, and no randomized trials have been performed. Recognizing the challenges regarding the conduct of randomized studies for such a rare pediatric cancer, we believe that multicenter trials through international collaborations can significantly enhance the available information.

Aqueous VEGF-A Levels as a Liquid Biopsy Biomarker of Retinoblastoma Vitreous Seed Response to Therapy

Purpose

Regression of retinoblastoma vitreous seeds (VS) during intravitreal chemotherapy can be delayed, resulting in supernumerary injections. Similarly, VS relapse may not be clinically evident at first. A predictive biomarker of tumor regression and relapse could help guide real-time clinical decision making. Retinoblastoma is an oxygen-sensitive tumor; paradoxically, VS survive in the hypoxic vitreous. We hypothesized that VS elaborate pro-angiogenic cytokines. The purpose was to determine if pro-angiogenic cytokine signatures from aqueous humor could serve as a biomarker of VS response to treatment.

Methods

Multiplex ELISA was performed on aqueous from rabbit eyes with human retinoblastoma VS xenografts to identify expressed proangiogenic cytokines and changes in aqueous cytokine levels during intravitreal treatment were determined. Confirmatory RNAscope in situ hybridization for VEGF-A was performed on human retinoblastoma tumor sections and VS xenografts from rabbits. For human eyes undergoing intravitreal chemotherapy, serial aqueous VEGF-A levels measured via VEGF-A-specific ELISA were compared to clinical response.

Results

VEGF-A was highly expressed in human retinoblastoma VS in the xenograft model, and was the only proangiogenic cytokine that correlated with VS disease burden. In rabbits, aqueous VEGF-A levels decreased in response to therapy, consistent with quantitative VS reduction. In patients, aqueous VEGF-A levels associated with clinical changes in disease burden (regression, stability, or relapse), with changes in VEGF-A levels correlating with clinical response.

Conclusions

Aqueous VEGF-A levels correlate with extent of retinoblastoma VS, suggesting that aqueous VEGF-A may serve as a predictive molecular biomarker of treatment response.

Intravitreal Topotecan for Vitreous Seeds in Retinoblastoma: A Long-term Review of 91 Eyes

PURPOSE

To study the long-term efficacy of intravitreal topotecan (IVT) for vitreous seeds in eyes with retinoblastoma and risk factors for their recurrence.

DESIGN

Retrospective, non-comparative, interventional study.

PARTICIPANTS

Ninety-one eyes of 90 patients with retinoblastoma treated between January 2013 and April 2019.

METHODS

Patients with recurrent or refractory vitreous seeds after completion of intravenous or intra-arterial chemotherapy were treated with IVT (30 μg/0.15 ml) by the safety-enhanced technique. The injection was repeated every 4 weeks until the regression of seeds. Patients with a minimum follow-up of 12 months were included in the analysis.

MAIN OUTCOME MEASURES

Primary outcome measures were vitreous seed regression and eye salvage. Secondary outcomes were risk factors for vitreous seed recurrence after treatment with IVT, vision salvage, and complications of IVT.

RESULTS

The median age of the patients was 18 months, with most having group D (n = 58 [64%]) and group E (n = 26 [29%]) retinoblastoma. Vitreous seeds were refractory in 46 eyes (51%) and recurrent in 45 eyes (49%). A total of 317 IVT injections were administered, with the median being 3 injections. The median number of IVT injections required was 2.5 injections for dust, 3 injections for sphere, and 5 injections for cloud morphologic features. Recurrence of vitreous seeds after IVT was seen in 17 eyes (19%) at a mean follow-up of 7.9 months. At a mean follow-up 34 months, vitreous seed regression was achieved in 88 eyes (97%) and eye salvage was achieved in 77 eyes (85%). Older age (P = 0.018) and recurrence of retinal tumor (15/17 eyes; P < 0.01) significantly increased the risk of vitreous seed recurrence. Cataract was the most common complication seen in 17 eyes (9%).

CONCLUSIONS

Intravitreal topotecan at an every 3- to 4-week regimen is effective against both refractory and recurrent vitreous seeds. The vitreous seed morphologic features correspond to the number of injections required for regression. Increasing age and recurrence of retinal tumor increase the risk of vitreous seed recurrence after treatment with IVT.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Update on chemotherapy modalities for retinoblastoma: Progress and challenges

Retinoblastoma stands as a paradigm of success in treating malignancies among pediatric patients. Over recent decades, the approach to managing retinoblastoma has evolved significantly, transitioning from the preservation of patients' lives to the preservation of eyes and vision while minimizing treatment-related complications. Chemotherapy, administered through diverse routes, has solidified its role as the cornerstone of retinoblastoma treatment. In addition to intravenous chemotherapy (IVC), alternative administration routes, including intraarterial (IAC), intravitreal, intracameral, and periocular delivery, have emerged as promising modalities for retinoblastoma management. Numerous studies have demonstrated outstanding outcomes, achieving nearly 100% salvage rates for eyes classified under groups A-C. However, for advanced intraocular retinoblastoma (groups D and E eyes), IAC appears to offer superior local control rates compared to IVC. Intravitreal injection of chemotherapeutic agents, when administered in a controlled and secure manner, holds promise in averting the need for enucleation and radiotherapy in advanced retinoblastoma cases presenting with vitreous seeds. The optimal chemotherapy strategy remains meticulously tailored based on numerous factors. This review provides a comprehensive update on chemotherapy across various routes, encompassing key considerations, dosages, administration methods, treatment outcomes, and potential complications. Furthermore, it explores emerging potential treatments and outlines future directions aimed at enhancing treatment outcomes.

Pushing the limit: Globe salvage of Group D retinoblastoma with severe vitreous seeding with intra-arterial chemotherapy and 15 cycles of intravitreal chemotherapy

Purpose

To report the successful treatment of persistent retinoblastoma vitreous seeding with 6 cycles of intra-arterial chemotherapy and 15 cycles of intravitreal chemotherapy injections.

Observations

A three-year-old female presented to the ocular oncology clinic with Group D retinoblastoma with severe vitreous seeding. The patient received 3 cycles of intra-arterial chemotherapy (melphalan, topotecan, and carboplatin) and 15 cycles of intravitreal chemotherapy (melphalan and combined melphalan/topotecan). Complete tumor regression and resolution of vitreous seeding was achieved. The best corrected visual acuity in the affected eye was 20/50.

Conclusions and Importance

Intravitreal chemotherapy for retinoblastoma vitreous seeding is often restricted to 8 treatment cycles. Patients who do not respond after 8 cycles face salvage therapy with radiation or enucleation. This is a case in which prolonged intravitreal chemotherapy delivery was well tolerated and resulted in sustained tumor remission, with useful visual acuity in the treated eye.

Ocular Survival Following Intravitreal Melphalan as Adjuvant Treatment for Vitreous Retinoblastoma Seeding

Purpose

To evaluate the efficacy of intravitreal chemotherapy for vitreous seeding in patients with retinoblastoma (Rb).

Design

Retrospective, single-arm cohort study.

Methods

This study was conducted at a tertiary eye center. Between 2013 and 2021, 27 patients (27 eyes) with vitreous Rb receiving adjuvant intravitreal melphalan (IVM) as secondary/salvage treatment in one eye were included. Patients who were unable to follow-up or treated elsewhere were excluded. Survival analysis was performed to assess the incidence of enucleation in the melphalan-treated group, as well as in bilateral cases with eyes receiving melphalan and those receiving standard treatment, consisting of chemotherapy, thermotherapy, and enucleation according to the disease stage.

Results

The median (interquartile range) follow-up time was 65 months (range, 34-83 months). Seventeen patients (63%) had bilateral disease. Sixteen eyes (59%) were saved. The Kaplan-Meier survival estimates for eyes receiving melphalan were 100% at 1 year (95% confidence interval [CI]:11.2-14.3), 75% (95% CI:14.2-48.9) at 3 years, and 50% at 5 years. Melphalan-treated patients with bilateral disease showed a significantly higher number of saved eyes than the standard treatment group (P=0.002). Tumor recurrence was the primary cause of enucleation, accounting for 36% of the cases. In the vitreous hemorrhage group, the odds of enucleation were 13 times higher (95% CI:1.04-165.28) than in the group without this condition.

Conclusion

IVM is an effective treatment option for vitreous seeds. After 3 years of follow-up, the estimated survival rate for saved eyes decreased, and vitreous hemorrhage significantly increased the likelihood of enucleation. Further studies are required to determine the precise effects of IVM.

Ocular survival after intra-arterial chemotherapy for retinoblastoma improves with accrual of experience and programmatic evolution

BACKGROUND

Intra-arterial chemotherapy (IAC) for the treatment of intraocular retinoblastoma has gained recognition as a method to improve ocular salvage; however, there is a paucity of evidence supporting treatment factors prognosticating ocular survival.

METHODS

All patients with retinoblastoma treated with IAC at a single institution between December 2008 and December 2019 were evaluated. Patient demographics, tumor classification, prior treatments, procedural data, other non-IAC therapies, adverse reactions, procedural complications, ocular outcomes, and overall survival were assessed via retrospective chart review. Factors suggestive of increased ocular survival were identified via univariate and multivariate analyses. The impact of accrued treatment experience was evaluated by grouping eyes by the respective year, IAC treatment was initiated.

RESULTS

Forty-nine eyes of 43 patients were treated for retinoblastoma with IAC (256 total procedures). At least grade 3 neutropenia was observed following 19% of IAC procedures. The risk of neutropenia was not statistically different between single or multidrug IAC. Comparing those who received balloon-assisted intra-arterial chemotherapy (bIAC) in more than two-thirds of cycles to those who did not, the risk of arterial access site complications was not statistically different. Multivariate analysis revealed a significantly lower risk of enucleation associated with treatment era in years (hazard ratio [HR] = 0.52-1.00, p < .05) and laser therapies (HR = 0.02-0.60, p < .05).

CONCLUSIONS

Ocular survival rates in patients treated with IAC for retinoblastoma at our institution have increased over time. Accrued treatment experience and programmatic changes have likely contributed. Larger, prospective series may lead to a better understanding of factors that consistently contribute to better ocular salvage.

Retinoblastoma seeds: impact on American Joint Committee on Cancer clinical staging

AIM

To investigate whether the American Joint Committee on Cancer (AJCC) clinical category cT2b needs to be subclassified by the type and distribution of retinoblastoma (RB) seeding.

METHODS

Multicentre, international registry-based data were collected from RB centres enrolled between January 2001 and December 2013. 1054 RB eyes with vitreous or subretinal seeds from 18 ophthalmic oncology centres, in 13 countries within six continents were analysed. Local treatment failure was defined as the use of secondary enucleation or external beam radiation therapy (EBRT) and was estimated with the Kaplan-Meier method.

RESULTS

Clinical category cT2b included 1054 eyes. Median age at presentation was 16.0 months. Of these, 428 (40.6%) eyes were salvaged, and 430 (40.8%) were treated with primary and 196 (18.6%) with secondary enucleation. Of the 592 eyes that had complete data for globe salvage analysis, the distribution of seeds was focal in 143 (24.2%) and diffuse in 449 (75.8%). The 5-year Kaplan-Meier cumulative globe-salvage (without EBRT) was 78% and 49% for eyes with focal and diffuse RB seeding, respectively. Cox proportional hazards regression analysis confirmed a higher local treatment failure risk with diffuse seeds as compared with focal seeds (hazard rate: 2.8; p<0.001). There was insufficient evidence to prove or disprove an association between vitreous seed type and local treatment failure risk(p=0.06).

CONCLUSION

This international, multicentre, registry-based analysis of RB eyes affirmed that eyes with diffuse intraocular distribution of RB seeds at diagnosis had a higher risk of local treatment failure when compared with focal seeds. Subclassification of AJCC RB category cT2b into focal vs diffuse seeds will improve prognostication for eye salvage.

Spotlight on Targeted Chemotherapy in Retinoblastoma: Safety, Efficacy, and Patient Outcomes

As the most common primary intraocular malignancy of childhood, retinoblastoma (RB) has had a complex journey in its management, following a course from enucleation as the first life-saving treatment to numerous globe-salvaging therapies during the last century. Currently, this potentially lethal disease has achieved high survival rates owing to multidisciplinary management and the introduction of neoadjuvant and multimodal chemotherapy. Therefore, the goal of treatment is shifting toward conserving the globe and vision as much as possible. Up until recently, many advanced cases of RB were enucleated primarily; however, targeted chemotherapy via the ophthalmic artery and management of intraocular seeding by local administration of chemotherapeutic agents have revolutionized the globe-conserving therapies. The added benefit of avoiding systemic complications of cytotoxic drugs resulted in these methods gaining popularity, and they are becoming a main part of care in many referral centers. Initially, there were some safety concerns regarding these approaches; however, increasing experience has shown that these modalities are relatively safe procedures and many complications can be averted by changing the choice of the drug and using some prophylactic measures. It is hoped that, in the near future, with advances in early diagnosis and patient-targeted molecular therapies, as well as gene-editing techniques, the patient's vision can be saved even in advanced RB.

Proteomics of Aqueous Humor as a Source of Disease Biomarkers in Retinoblastoma

Aqueous humor (AH) can be easily and safely used to evaluate disease-specific biomarkers in ocular disease. The aim of this study was to identify specific proteins biomarkers in the AH of retinoblastoma (RB) patients at various stages of the disease. We analyzed the proteome of 53 AH samples using high-resolution mass spectrometry. We grouped the samples according to active vitreous seeding (Group 1), active aqueous seeding (Group 2), naive RB (group 3), inactive RB (group 4), and congenital cataracts as the control (Group 5). We found a total of 889 proteins in all samples. Comparative parametric analyses among the different groups revealed three additional proteins expressed in the RB groups that were not expressed in the control group. These were histone H2B type 2-E (HISTH2B2E), InaD-like protein (PATJ), and ubiquitin conjugating enzyme E2 V1 (UBE2V1). Upon processing the data of our study with the OpenTarget Tool software, we found that glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and CD44 were more highly expressed in the RB groups. Our results provide a proteome database regarding AH related to RB disease that may be used as a source of biomarkers. Further prospective studies should validate our finding in a large cohort of RB patients.

Ruptured retinoblastoma: management in a rare case scenario

A preschool child presented with white reflex in left eye since 2 months. Examination under anaesthesia revealed left eye retinoblastoma group D as per international classification of retinoblastoma. In collaboration with medical oncologist, systemic chemotherapy was started. After two cycles of systemic chemotherapy, tumour ruptured into the vitreous cavity suspending the tumour cells in the vitreous jelly. After a combination of systemic and intravitreal chemotherapy with adjuvant transpupillary thermotherapy of the residual retinal tumour, retinoblastoma regressed completely with corresponding flat scar.

pRB-Depleted Pluripotent Stem Cell Retinal Organoids Recapitulate Cell State Transitions of Retinoblastoma Development and Suggest an Important Role for pRB in Retinal Cell Differentiation

Retinoblastoma (Rb) is a childhood cancer of the developing retina, accounting for up to 17% of all tumors in infancy. To gain insights into the transcriptional events of cell state transitions during Rb development, we established 2 disease models via retinal organoid differentiation of a pRB (retinoblastoma protein)-depleted human embryonic stem cell line (RB1-null hESCs) and a pRB patient-specific induced pluripotent (iPSC) line harboring a RB1 biallelic mutation (c.2082delC). Both models were characterized by pRB depletion and accumulation of retinal progenitor cells at the expense of amacrine, horizontal and retinal ganglion cells, which suggests an important role for pRB in differentiation of these cell lineages. Importantly, a significant increase in the fraction of proliferating cone precursors (RXRγ+Ki67+) was observed in both pRB-depleted organoid models, which were defined as Rb-like clusters by single-cell RNA-Seq analysis. The pRB-depleted retinal organoids displayed similar features to Rb tumors, including mitochondrial cristae aberrations and rosette-like structures, and were able to undergo cell growth in an anchorage-independent manner, indicative of cell transformation in vitro. In both models, the Rb cones expressed retinal ganglion and horizontal cell markers, a novel finding, which could help to better characterize these tumors with possible therapeutic implications. Application of Melphalan, Topotecan, and TW-37 led to a significant reduction in the fraction of Rb proliferating cone precursors, validating the suitability of these in vitro models for testing novel therapeutics for Rb.

Single vesicle analysis of aqueous humor in pediatric ocular diseases reveals eye specific CD63-dominant subpopulations

Aqueous humor (AH), the clear fluid in front of the eye, maintains the pressure and vitality of ocular tissues. This fluid is accessible via the clear cornea which enables use of AH as a liquid biopsy source of biomarkers for intraocular disease. Extracellular vesicles are detectable in the AH and small extracellular vesicles (sEVs) are present in the AH from adults. However, EVs in AH from pediatric eyes in vivo have never previously been explored. We know very little about the heterogeneity of AH EV populations in ocular disease. Twenty-seven processing-free AH samples from 19 patients across four different pediatric ocular diseases were subjected to Nanoparticle Tracking Analysis (NTA) and Single Particle-Interferometric Reflectance Imaging Sensor (SP-IRIS) analysis. NTA demonstrated the concentration of AH EV/EPs is 3.11 × 109-1.38 × 1010 particles/ml; the majority sized 76.8-103 nm. SP-IRIS revealed distinct patterns of tetraspanin expression of AH sEVs. An enriched mono-CD63+ sEV subpopulation identified in AH indicates this is a potential AH-specific biomarker. In the setting of retinoblastoma there was a more heterogeneous population of sEVs which normalized with treatment. This suggests a potential clinical application of direct measurement of sEV subpopulations in AH samples to monitor successful tumor response to therapy.

Aqueous seeding in retinoblastoma: Classification and clinicopathological correlation

PURPOSE

To correlate clinical types of aqueous seeds with histopathological characteristics in primarily enucleated eyes with retinoblastoma (RB).

DESIGN

Retrospective study PARTICIPANTS: Twenty-five patients with RB METHODS: Clinicopathological correlation of aqueous seeds in 25 eyes that underwent primary enucleation and had evidence of aqueous seeds MAIN OUTCOME MEASURES: Histopathological characteristics of aqueous seeds RESULTS: All 25 enucleated eyes were classified as group E RB based on International Classification of Intraocular Retinoblastoma. Clinically, type 1 aqueous seeds were noted in 9 (36%), type 2 in 8 (32%), and type 3 in 8 (32%). Based on histopathology, type 1 seeds were individual tumor cells admixed with macrophages and non-viable tumor cells; type 2 seeds were spheres and are classified into two subtypes a) Spheres without central necrosis containing solid clusters of tumor cells b) Spheres with central necrosis containing central core of necrotic cells surrounded by viable tumor cells; and type 3 seeds were tumor cells admixed with macrophages and RBCs that sediment into angle. Aqueous seeding involved both anterior (n=25; 100%) and posterior chambers (n=18; 72%). Significant intraocular tissue (Schlemm's canal, trabecular meshwork, ciliary body, choroid, optic nerve, sclera) infiltration of RB was noted in 23 (92%) cases. Compared to type 1 and 2 seeds, patients with type 3 seeds were more commonly associated with ciliary body infiltration (41% vs 88%; p=0.04). Over a mean follow-up period of 57 months (median, 49 months; range, <1 to 175 months), metastasis and death was noted in 3 (12%) patients.

CONCLUSION

Similar to vitreous seeds in RB, aqueous seeds have three distinct histopathological types. Posterior chamber seeds are noted in 72% cases presenting with anterior chamber seeds indicating the need for treatment of both the chambers whenever conservative treatment is attempted in suitable cases. Most (92%) cases with primary aqueous seeding are associated with other high-risk histopathology features, suggesting a cautious approach for conservative management in these cases.

Intravitreal HDAC Inhibitor Belinostat Effectively Eradicates Vitreous Seeds Without Retinal Toxicity In Vivo in a Rabbit Retinoblastoma Model

Purpose

Current melphalan-based regimens for intravitreal chemotherapy for retinoblastoma vitreous seeds are effective but toxic to the retina. Thus, alternative agents are needed. Based on the known biology of histone deacetylases (HDACs) in the retinoblastoma pathway, we systematically studied whether the HDAC inhibitor belinostat is a viable, molecularly targeted alternative agent for intravitreal delivery that might provide comparable efficacy, without toxicity.

Methods

In vivo pharmacokinetic experiments in rabbits and in vitro cytotoxicity experiments were performed to determine the 90% inhibitory concentration (IC₉₀). Functional toxicity by electroretinography and structural toxicity by optical coherence tomography (OCT), OCT angiography, and histopathology were evaluated in rabbits following three injections of belinostat 350 µg (2× IC₉₀) or 700 µg (4× IC₉₀), compared with melphalan 12.5 µg (rabbit equivalent of the human dose). The relative efficacy of intravitreal belinostat versus melphalan to treat WERI-Rb1 human cell xenografts in rabbit eyes was directly quantified. RNA sequencing was used to assess belinostat-induced changes in RB cell gene expression.

Results

The maximum nontoxic dose of belinostat was 350 µg, which caused no reductions in electroretinography parameters, retinal microvascular loss on OCT angiography, or retinal degeneration. Melphalan caused severe retinal structural and functional toxicity. Belinostat 350 µg (equivalent to 700 µg in the larger human eye) was equally effective at eradicating vitreous seeds in the rabbit xenograft model compared with melphalan (95.5% reduction for belinostat, P < 0.001; 89.4% reduction for melphalan, P < 0.001; belinostat vs. melphalan, P = 0.10). Even 700 µg belinostat (equivalent to 1400 µg in humans) caused only minimal toxicity. Widespread changes in gene expression resulted.

Conclusions

Molecularly targeted inhibition of HDACs with intravitreal belinostat was equally effective as standard-of-care melphalan but without retinal toxicity. Belinostat may therefore be an attractive agent to pursue clinically for intravitreal treatment of retinoblastoma.

Safety and Efficacy of Intravitreal Chemotherapy (Melphalan) to Treat Vitreous Seeds in Retinoblastoma

Background: Active vitreous seeds in eyes with retinoblastoma (Rb) adversely affects the treatment outcome. This study aimed to investigate the safety and efficacy of intravitreal melphalan chemotherapy (IViC) as a treatment for recurrent and refractory vitreous seeds in patients with Rb.

Methods: We used a retrospective non-comparative study of patients with intraocular Rb who had vitreous seeds and were treated by IViC (20–30 μg of melphalan) using the safety-enhanced anti-reflux technique. Tumor response, ocular toxicity, demographics, clinical features, and survival were analyzed.

Results: In total, 27 eyes were treated with 108 injections for recurrent (16 eyes) or refractory (11 eyes) vitreous seeds after failed systemic chemotherapy. A total of 15 (56%) were males, and 20 (74%) had bilateral disease. At diagnosis, the majority (n = 21) of the injected eyes were group D, and n = 6 were group C. Vitreous seeds showed complete regression in 21 (78%) eyes; 100% (n = 10) for eyes with focal seeds; 65% (n = 11/17 eyes) for eyes with diffuse seeds (p = 0.04); 7 (64%) eyes with refractory seeds; and 14 (87%) eyes with recurrent seeds showed complete response (p = 0.37). In total, 16 (59%) eyes developed side effects: retinal toxicity (48%), pupillary synechiae (15%), cataracts (30%), iris atrophy (7%), and retinal and optic atrophy (4%). Only one child was lost to follow-up whose family refused enucleation and none developed orbital tumor recurrence or distant metastasis.

Conclusion: IViC with melphalan is effective (more for focal than diffuse seeding) and a relatively safe treatment modality for Rb that can improve the outcomes of eye salvage procedures. However, unexpected toxicity can occur even with the standard dose of 20–30 μg.

Current Indications of Secondary Enucleation in Retinoblastoma Management: A Position Paper on Behalf of the European Retinoblastoma Group (EURbG)

Simple Summary

Although secondary enucleation (SE) is the treatment of choice for retinoblastoma eyes that did not respond favorably to conservative therapies, clear criteria for its indication are, however, currently missing. In this position paper on behalf of the European Retinoblastoma Group (EURbG), we discuss the available literature on SE, including its influence on metastases rate and survival, and propose guidelines to assist decision-making to interrupt eye-preserving therapies depending on the availabilities of advanced diagnostic and therapeutic modalities. Absolute indications to SE may be restricted to eyes with refractory tumor activity resisting all salvage treatments or eyes under apparent tumor control but no visual potential and irreducible complications. In contrast, eyes with an obscured optic nerve head and/or ocular complications amenable to specific surgical or medical management can be considered relative indications, provided that appropriate follow-up can be implemented and that parents are fully aware of a residual risk.

Abstract

Secondary enucleation (SE) puts an irreversible end to eye-preserving therapies, whenever their prolongation is expected to violate the presumed state of metastatic grace. At present, it must be acknowledged that clear criteria for SE are missing, leading to empiric and subjective indications commonly related to disease progression or relapse, disease persistence masking the optic nerve head or treatment-related complications obscuring the fundus view. This absence of evidence-based consensus regarding SE is explained by the continuously moving frontiers of the conservative management as a result of diagnostic and therapeutic advances, as well as by the lack of studies sufficiently powered to accurately stratify the risk of metastasis in conservatively treated patients. In this position paper of the European Retinoblastoma Group (EURbG), we give an overview of the progressive shift in the indications for SE over the past decades and propose guidelines to assist decision-making with respect to when SE becomes imperative or recommended, with corresponding absolute and relative SE indications. Further studies and validation of biologic markers correlated with the risk of metastasis are expected to set more precisely the frontiers of conservative management and thus consensual criteria for SE in the future.

Comprehensive Somatic Copy Number Analysis Using Aqueous Humor Liquid Biopsy for Retinoblastoma

Simple Summary

Aqueous humor (AH) liquid biopsy is an enriched source of cell-free circulating tumor-derived DNA for retinoblastoma (RB). The use of this AH liquid biopsy allows for genomic analysis of eyes in the absence of tumor tissue. Development of this platform was critical because direct tumor biopsy is prohibited in RB due to risk of extraocular tumor spread. In this retrospective study, we provide comprehensive, whole-genome analysis of the somatic copy number alterations (SCNAs) in 68 eyes of 64 RB patients. We show that the prevalence of specific SCNAs differ between eyes that required immediate enucleation (surgical removal) and eyes that were attempted to be saved but subsequently failed treatment, requiring secondary enucleation. Increases in chromosomal instability, or higher number of broad genomic alterations, predict higher risk clinical and biomarker features in these eyes. Prospective analyses are needed to further determine the clinical relevance and application of these findings.

Abstract

Aqueous humor (AH) liquid biopsy has been established as a surrogate tumor biopsy for retinoblastoma (RB). Previous AH studies have focused on highly recurrent RB somatic copy number alterations (SCNAs) including gain of 1q, 2p, 6p, and loss of 13q and 16q. In this retrospective study, we provide a comprehensive, whole-genome analysis of RB SCNAs and evaluate associated clinical features for 68 eyes of 64 RB patients from whom AH was obtained between December 2014 and October 2020. Shallow whole-genome sequencing of AH cell-free DNA was performed to assess for SCNAs. The prevalence of specific non-highly recurrent SCNAs, such as 20q gain and 8p loss, differed between primarily and secondarily enucleated eyes. Increases in chromosomal instability predict more advanced seeding morphology (p = 0.015); later age of diagnosis (p < 0.0001); greater odds of an endophytic tumor growth pattern (without retinal detachment; p = 0.047); tumor heights >10 mm (p = 0.09); and containing 6p gain, a biomarker of poor ocular prognosis (p = 0.004). The AH liquid biopsy platform is a high-yield method of whole-genome RB SCNA analysis, and SCNAs are associated with numerous clinical findings in RB eyes. Prospective analyses are encouraged to further elucidate the clinical relevance of specific SCNAs in RB.

Intravenous Chemotherapy for Retinoblastoma in the Era of Intravitreal Chemotherapy: A Systematic Review

Purpose

The published data on ocular survival following intravenous chemotherapy of retinoblastoma (RB) seems to be skewed by evolving practice patterns induced by use of intravitreal chemotherapy (iVitc). We aimed to explore potential role of iVitc for vitreous seeding for patients treated with intravenous chemotherapy (IVC).

Methods

A literature search was performed to identify cases of RB treated with primary IVC prior to advent of iVitc by various search engines (PubMed, Medline, and Google) from 1992 to 2018. Studies were excluded if number of cases were less than 40 or lacked data related to type of recurrence and its treatment. Rates and patterns of recurrence and its management were categorized.

Results

Out of 15 studies identified, only 10 studies (797 eyes) met the inclusion criteria. The mean age at presentation was 15.3 months (range 0-192.8 months). Unilateral cases represented 25% of the cohort. The ocular survival rate with primary IVC was 63% (500/797 eyes). Of the 297 eyes (37%) that failed IVC therapy, additional 99 eyes could be salvaged with EBRT (599/797 eyes, 75%). Remaining 198 eyes were enucleated (198/797 eyes 25%). K-M survival analysis could not be done due lack of sufficient data. Recurrences that occurred (mean 12.2 months) after completion of primary IVC included relapse of retinal tumor (143 eyes [48%]), vitreous seeding (73 eyes [25%]), subretinal seeding (49 eyes [16%]), or any combination (103 eyes [35%]). Out of 73 eyes with vitreous seeding, additional 66 eyes (90%) would have been salvaged with iVitc, potentially improving ocular survival rates to 71% (500 + 66/797).

Conclusions

Evolving practice patterns of RB treatment have unfavorably skewed published ocular survival rates following IVC. With incorporation of iVitc, the ocular survival rates with IVC can be potentially improved to be non-inferior to those achieved with intra-arterial chemotherapy.

Evaluation of intravitreal topotecan dose levels, toxicity and efficacy for retinoblastoma vitreous seeds: a preclinical and clinical study

Background

Current melphalan-based intravitreal regimens for retinoblastoma (RB) vitreous seeds cause retinal toxicity. We assessed the efficacy and toxicity of topotecan monotherapy compared with melphalan in our rabbit model and patient cohort.

Methods

Rabbit experiments: empiric pharmacokinetics were determined following topotecan injection. For topotecan (15 μg or 30 µg), melphalan (12.5 µg) or saline, toxicity was evaluated by serial electroretinography (ERG) and histopathology, and efficacy against vitreous seed xenografts was measured by tumour cell reduction and apoptosis induction. Patients: retrospective cohort study of 235 patients receiving 990 intravitreal injections of topotecan or melphalan.

Results

Intravitreal topotecan 30 µg (equals 60 µg in humans) achieved the IC₉₀ across the rabbit vitreous. Three weekly topotecan injections (either 15 µg or 30 µg) caused no retinal toxicity in rabbits, whereas melphalan 12.5 µg (equals 25 µg in humans) reduced ERG amplitudes 42%–79%. Intravitreal topotecan 15 µg was equally effective to melphalan to treat WERI-Rb1 cell xenografts in rabbits (96% reduction for topotecan vs saline (p=0.004), 88% reduction for melphalan vs saline (p=0.004), topotecan vs melphalan, p=0.15). In our clinical study, patients received 881 monotherapy injections (48 topotecan, 833 melphalan). Patients receiving 20 µg or 30 µg topotecan demonstrated no significant ERG reductions; melphalan caused ERG reductions of 7.6 μV for every injection of 25 µg (p=0.03) or 30 µg (p<0.001). Most patients treated with intravitreal topotecan also received intravitreal melphalan at some point during their treatment course. Among those eyes treated exclusively with topotecan monotherapy, all eyes were salvaged.

Conclusions

Taken together, these experiments suggest that intravitreal topotecan monotherapy for the treatment of RB vitreous seeds is non-toxic and effective.

Response criteria for intraocular retinoblastoma: RB-RECIST

Standardized guidelines for assessing tumor response to therapy are essential for designing and conducting clinical trials. The Response Evaluation Criteria In Solid Tumors (RECIST) provide radiological standards for assessment of solid tumors. However, no such guidelines exist for the evaluation of intraocular cancer, and ocular oncology clinical trials have largely relied on indirect measures of therapeutic response-such as progression-free survival-to evaluate the efficacy of treatment agents. Herein, we propose specific criteria for evaluating treatment response of retinoblastoma, the most common pediatric intraocular cancer, and emphasize a multimodal imaging approach for comprehensive assessment of retinoblastoma tumors in clinical trials.

Complete preclinical platform for intravitreal chemotherapy drug discovery for retinoblastoma: Assessment of pharmacokinetics, toxicity and efficacy using a rabbit model

Current melphalan-based intravitreal chemotherapy regimens for retinoblastoma vitreous seeds are effective, but cause significant ocular toxicity. We describe protocols for each step of a drug discovery pipeline for preclinical development of novel drugs to maximize efficacy and minimize toxicity. These protocols include: 1) determination of vitreous pharmacokinetics in vivo, 2) in vitro assessment of drug cytotoxicity against retinoblastoma based on empiric pharmacokinetics, 3) back-calculation of minimum injection dose to achieve therapeutic concentrations, 4) in vivo determination of maximum-tolerable intravitreal dose, using a multimodal, structural and functional toxicity-assessment platform, and 5) in vivo determination of drug efficacy using a rabbit orthotopic xenograft model of retinoblastoma vitreous seeds. We likewise describe our methodology for direct quantitation of vitreous seeds, and the statistical methodology for assessment of toxicity and efficacy in evaluating novel drugs, as well as for comparisons between drugs.•Multi-step pipeline for intravitreal chemotherapy drug discovery for retinoblastoma, using novel rabbit models.•Detailed protocols for determination of vitreous pharmacokinetics, calculation of optimal dose to inject to achieve therapeutic vitreous levels, determination of maximum tolerable dose using a novel complete toxicity-assessment platform, and in vivo efficacy against retinoblastoma using methodology to directly quantify vitreous tumor burden.•Associated statistical methodology is also presented.

Vitreous Seed Classification and Regression Patterns in Eyes With Retinoblastoma

Purpose:

This work subclassifies retinoblastoma vitreous seeds and evaluates the efficacy, regression patterns, and adverse effects of combination intravitreal melphalan and topotecan chemotherapy for resistant and recurrent vitreous seeds.

Methods:

A retrospective review of medical records was conducted of patients with retinoblastoma and resistant or recurrent vitreous seeds who were treated with intravitreal melphalan and topotecan injections from August 2014 to July 2018. Main outcome measures included regression pattern, time for regression, time for recurrence of seeds, treatment outcomes, and ocular toxicity.

Results:

Nineteen eyes received 138 intravitreal injections over 74 treatment sessions (mean, 7.26 injections per eye); vitreous seeds regressed in 18 eyes. Of cloud vitreous seeds, curvilinear (n = 2) and sphero-linear (n = 2) subtypes were observed. During regression, some sphere seeds showed an intermediary streak-like pattern and took longer to regress (mean, 11.13 ± 14.05 months and 11.67 ± 8.62 injections) than those without the intermediary streak-like pattern (mean, 3.55 ± 2.57 months and 4.2 ± 1.87 injections). Mean follow-up was 34.87 ± 21.09 months (median, 35 months; range, 11-96 months). Anterior segment toxicity was seen in 10 (53%) eyes and posterior segment toxicity in 5 (26%) eyes. Kaplan-Meier survival estimates for globe salvage at 2 years was 94% and 73% at 5 years. Kaplan-Meier survival for vitreous seed–free status was 94% at 2 years and 65% at 5 years.

Conclusions:

An expanded vitreous seed classification system that further subcategorizes hitherto unrecognized vitreous seed morphology is needed. An intermediate streaking process results in a prolonged regression time for sphere vitreous seeds.

Intravitreal melphalan hydrochloride vs propylene glycol-free melphalan for retinoblastoma vitreous seeds: Efficacy, toxicity and stability in rabbits models and patients

The use of intravitreal chemotherapy has revolutionized the treatment of advanced intraocular retinoblastoma, as intravitreal melphalan has enabled difficult-to-treat vitreous tumor seeds to be controlled, leading to many more eyes being saved. However, melphalan hydrochloride (MH) degrades rapidly in solution, increasing logistical complexity with respect to time between medication preparation and administration for intravitreal administration under anesthesia for retinoblastoma. A new propylene glycol-free melphalan (PGFM) formulation has greater stability and could therefore improve access and adoption of intravitreal chemotherapy, allowing more children to retain their eye(s). We compared the efficacy and toxicity of both formulations, using our rabbit xenograft model and clinical patient experience. Three weekly 12.5 μg intravitreal injections of MH or PGFM (right eye), and saline (left eye), were administered to immunosuppressed rabbits harboring human WERI-Rb1 vitreous seed xenografts. Residual live cells were quantified directly, and viability determined by TUNEL staining. Vitreous seeds were reduced 91% by PGFM (p = 0.009), and 88% by MH (p = 0.004; PGFM vs. MH: p = 0.68). All residual cells were TUNEL-positive (non-viable). In separate experiments to assess toxicity, three weekly 12.5 μg injections of MH, PGFM, or saline were administered to non-tumor-bearing rabbits. Serial electroretinography, optical coherence tomography (OCT) and OCT-angiography were performed. PGFM and MH both caused equivalent reductions in electroretinography amplitudes, and loss of retinal microvasculature on OCT-angiography. The pattern of retinal degeneration observed on histopathology suggested that segmental retinal toxicity associated with all melphalan formulations was due to a vitreous concentration gradient-effect. Efficacy and toxicity were assessed for PGFM given immediately (within 1 h of reconstitution) vs. 4 h after reconstitution. Immediate- and delayed-administration of PGFM showed equivalent efficacy and toxicity. In addition, we evaluated efficacy and toxicity in patients (205 eyes) with retinoblastoma vitreous seeds, who were treated with a total of 833 intravitreal injections of either MH or PGFM as standard of care. Of these, we analyzed 118 MH and 131 PGFM monotherapy injections in whom serial ERG measurements were available to model retinal toxicity. Both MH and PGFM caused reductions in electroretinography amplitudes, but with no statistical difference between formulations. Comparing those patient eyes treated exclusively with PGFM versus those treated exclusively with MH, efficacy for tumor control and globe salvage was equivalent (PGFM vs. MH: 96.2% vs. 93.8%, p = 0.56), but PGFM-treated eyes received fewer injections than MH-treated eyes (average 3.2 ± 1.9 vs. 6.4 ± 2.1 injections, p < 0.0001). Taken together, these rabbit experiments and our clinical experience in retinoblastoma patients demonstrate that MH and PGFM have equivalent efficacy and toxicity. PGFM was more stable, with no decreased efficacy or increased toxicity even 4 h after reconstitution. We therefore now use PGFM over traditional MH for our patients for intravitreal treatment of retinoblastoma.

Intravitreal Melphalan for Retinoblastoma: The Impact of Toxicity on Recurrence and Ultimate Globe Salvage

Introduction

Intravitreal melphalan (IVM) has emerged as an efficacious treatment for vitreous seeding in retinoblastoma. Although rarely severe, IVM-related toxicity may be treatment limiting. There is paucity of data on the impact of IVM toxicity on new tumor formation and ultimate globe salvage.

Objectives

To investigate whether the grade of retinal toxicity post-IVM impacts retinal and seeding tumor recurrence, as well as the overall ability to salvage the eye.

Methods

A single-institution retrospective chart review was performed on 47 eyes of 42 patients who received systemic intravenous chemotherapy followed by IVM as salvage treatment for persistent or recurrent vitreous seeding. Chorioretinal toxicity was graded from 0 to 5.

Results

Toxicity grade was inversely associated with the risk of recurrence, where a one-unit increase in toxicity grade correlated with nearly a 54% reduction in the odds of tumor recurrence (OR 0.46 [0.25-0.84], p = 0.01). Similarly, toxicity grade was related to enucleation, where a one-unit increase in toxicity grade was associated with a 31% reduction in the odds of undergoing enucleation (OR 0.69 [0.40-1.18], p = 0.17).

Conclusions

While retinoblastoma therapy aims to limit toxicity, especially visually significant toxicity, eyes with higher grades of post-IVM toxicity are less likely to have retinal and seeding tumor recurrence.

A systematic review of ultrasound biomicroscopy use in pediatric ophthalmology

Ultrasound biomicroscopy (UBM) is the only available option for noninvasive, high-resolution imaging of the intricate iridociliary complex, and for anterior segment imaging with corneal haze or opacity. While these unique features render UBM essential for specific types of trauma, congenital anomalies, and anterior segment tumors, UBM imaging has found clinical utility in a broad spectrum of diseases for structural assessments not limited to the anterior intraocular anatomy, but also for eyelid and orbit anatomy. This imaging tool has a very specific niche in the pediatric population where anterior segment disease can be accompanied by corneal opacity or clouding, and anomalies posterior to the iris may be present. Pediatric patients present additional diagnostic challenges. They are often unable to offer detailed histories or fully cooperate with examination, thus amplifying the need for high-resolution imaging. This purpose of this systematic review is to identify and synthesize the body of literature involving use of UBM to describe, evaluate, diagnose, or optimize treatment of pediatric ocular disease. The collated peer-reviewed research details the utility of this imaging modality, clarifies the structures and diseases most relevant for this tool, and describes quantitative and qualitative features of UBM imaging among pediatric subjects. This summary will include information about the specific applications available to enhance clinical care for pediatric eye disease.

Chemotherapy for Retinoblastoma: Impact of Intravitreal Chemotherapy

ABSTRACT

Chemotherapy is now the primary treatment of retinoblastoma in eyes with visual potential or those that are considered not advanced for retinoblastoma. In addition to intravenous chemotherapy (IVC), drugs delivered via alternative routes such as intra-arterial and intravitreal administration have emerged as promising options for management of retinoblastoma. Various studies have shown excellent results in salvaging nearly 100% of groups A-C eyes; however, intra-arterial chemotherapy (IAC) seems to offer superior local control rates as compared with IVC for advanced intraocular retinoblastoma (groups D and E eyes). Intravitreal chemotherapy (IVitC), that delivers the highest concentration of drug in the vitreous cavity while minimizing systemic drug concentration, has emerged in recent years (2012) as an effective treatment for refractory or persistent vitreous seeding. The role of concomitant and subsequent therapies is an important consideration, particularly the use of IVitC in combination with IAC. As IVitC became acceptable during the era of IAC, most of the patients treated previously with IVC did not receive IVitC. Therefore, it is possible that some of the IVC failures could have been avoided with the use of IVitC. We provide our perspective of published data that seems to be skewed by evolving practice patterns that project enhanced efficacy of IAC when compared with historic control rates achieved with IVC. In absence of better-quality data or randomized controlled trials, it is hard to establish superiority of one treatment over the other.

Chromosome 6p Amplification in Aqueous Humor Cell-Free DNA Is a Prognostic Biomarker for Retinoblastoma Ocular Survival

Aqueous humor contains tumor-derived cell-free DNA (cfDNA) and can serve as a liquid biopsy for retinoblastoma. We previously associated somatic copy-number alteration (SCNA) 6p gain with a 10-fold increased risk of enucleation. Here we provide a 2-year update to further explore 6p gain as a prognostic biomarker for ocular survival. Patients diagnosed with retinoblastoma from December 2014 to July 2019 from whom aqueous humor was sampled were included. cfDNA was extracted and shallow whole-genome sequencing performed to identify highly recurrent retinoblastoma SCNAs (gain of 1q, 2p, 6p, loss of 13q, 16q). 116 aqueous humor samples from 50 eyes of 46 patients were included: 27 eyes were salvaged, 23 were enucleated. Highly recurrent retinoblastoma SCNAs were found in 66% eyes. 6p gain was the most prevalent SCNA (50% eyes). It was particularly more prevalent in enucleated eyes (73.9%) than in salvaged eyes (29.6%; P = 0.004). 6p gain in aqueous humor cfDNA portended nearly 10-fold increased odds of enucleation (OR = 9.87; 95% confidence interval = 1.75-55.65; P = 0.009). In the enucleated eyes, 6p gain was associated with aggressive histopathologic features, including necrosis, higher degrees of anaplasia, and focal invasion of ocular structures. With extended follow-up and nearly double the aqueous humor samples, we continue to demonstrate 6p gain as a potential prognostic biomarker for retinoblastoma. IMPLICATIONS: Aqueous humor is a high-yield source of tumor-derived DNA in retinoblastoma eyes. Detection of 6p gain in the aqueous humor allows for targeted, patient-centered therapies based on this molecular prognostic marker. Prospective, multicenter studies with aqueous humor sampled from all eyes at diagnosis are warranted to validate these findings.

Comparison of intravitreal melphalan with and without topotecan in the management of vitreous disease in retinoblastoma

PURPOSE

To evaluate clinical outcomes and enucleation rates after intravitreal melphalan (IVM) alone and after IVM combined with intravitreal topotecan (IVT) for the treatment of vitreous disease, and to a lesser extent subretinal and retrohyaloid seeds, in patients with retinoblastoma.

STUDY DESIGN

A retrospective analysis of 77 eyes of 72 consecutive patients.

METHODS

Demographic data, classification of tumors, seed type (dust, sphere or cloud) before injection and at the end of follow-up, injection type (IVM or IVM+IVT), doses of IVM and IVT, number of injections, follow-up time, enucleation status and side effects were recorded. Cox regression analysis and log-rank test for Kaplan-Meier curves were performed.

RESULTS

Of 77 eyes, 40 received IVM alone (group 1) and 37 received IVM+IVT (group 2). Enucleation rates were 62.5% (n=25) in group 1 and 10.8% (n=4) in group 2 (p=0.001). Median eye survival was 23.6 months in group 1 and 25.6 months in group 2. Mantel-Cox test revealed statistically significant differences between Kaplan-Meier curves of group 1 and 2 (p=0.022). Multiple Cox regression analysis showed a significantly elevated enucleation rate associated with: IVM only treatment group (p=0.019) and pre-injection cloud type of seeding (p=0.014).

CONCLUSION

The combined use of intravitreal melphalan and topotecan provides significantly better results in terms of avoiding enucleation and vitreal and subretinal seed control.

Preclinical studies reveal MLN4924 is a promising new retinoblastoma therapy

RB1 loss (RB1 null ) or MYCN amplification (MYCN amp ) in fetal human retina causes retinoblastoma. SKP2 loss kills RB1 null cells, but small molecule SKP2 inhibitors remain unexplored therapeutically. Whether SKP2 is synthetic lethal in MYCN amp retinoblastoma is unclear. SKP2 is the substrate recognition component of two Cullin-RING Ligase complexes (CRL1SKP2/SCFSKP2, and CRL4SKP2), a family of multiprotein E3 ubiquitin ligases. NEDD8 activating enzyme (NAE) is required for Cullin neddylation and thus CRL activation. Here, we show that the NAE inhibitor, Pevonedistat (MLN4924), potently inhibits RB1 null and MYCN amp tumors. Intravitreal MLN4924 suppressed multiple human xenografts with EC80s from 20 ng to 3.5 μg. Maximum tolerated dose (MTD) was 10-30 μg, highlighting a favorable therapeutic window. Inhibition of Cullin neddylation was similar in all cases, but cellular effects ranged from G1 arrest with apoptosis to G2/M arrest with endoreplication. However, even in less sensitive lines (EC50 ≈ 1 μM), prolonged exposure was lethal or induced persistent cytostasis. Mechanistically, depleting any single Cullin did not fully recapitulate drug phenotypes, but sensitivity to SKP2 loss correlated with that of drug. Thus, intravitreal MLN4924 is a promising new retinoblastoma therapy, mimicking the cancer-specific lethality of eliminating SKP2 complexes.

A temperature-sensitive phase-change hydrogel of topotecan achieves a long-term sustained antitumor effect on retinoblastoma cells

Background

Retinoblastoma (Rb) is one of the most common malignancies among children. Following early diagnosis and prompt treatment, the clinical outcome or prognosis of Rb is promising. However, the prognosis or survival rates of patients with late-stage Rb remain poor. Current therapeutic strategies for advanced Rb mainly involve the use of advanced chemotherapeutic options. However, the efficacy of these strategies is not satisfactory. Therefore, the development of novel strategies to achieve a more effective antitumor effect on late-stage Rb is of crucial importance.

Methods and materials

Topotecan was dissolved in phosphate-buffered saline and prepared into a temperature-sensitive phase-change hydrogel (termed Topo-Gel). Moreover, Topo-Gel was injected into tumor tissues formed by Y79 cells (an Rb cell line) in nude mice to examine the long-term release and long-acting antitumor effect of Topo-Gel on Rb tumors.

Results

Topo-Gel transforms from liquid to a hydrogel at near body temperatures (phase-change temperature [T_1/2] was 37.23±0.473 °C), and maintains the slow release of topotecan in Rb tumor tissues. Following the subcutaneous injection of Topo-Gel, the treatment induced long-acting inhibition of tumor growth and relieved the adverse effects associated with topotecan. Topo-Gel, a temperature-sensitive phase-change hydrogel, is a slow-release system that prolongs the presence of topotecan in Rb tissues, and preserves the efficacy of topotecan in the long term.

Conclusion

Preparation of topotecan into a temperature-sensitive phase-change hydrogel achieves a long-term sustained antitumor effect on Rb cells, and may be a useful strategy for the treatment of intraocular Rb.

Conservative management of retinoblastoma: Challenging orthodoxy without compromising the state of metastatic grace. "Alive, with good vision and no comorbidity"

Retinoblastoma is lethal by metastasis if left untreated, so the primary goal of therapy is to preserve life, with ocular survival, visual preservation and quality of life as secondary aims. Historically, enucleation was the first successful therapeutic approach to decrease mortality, followed over 100 years ago by the first eye salvage attempts with radiotherapy. This led to the empiric delineation of a window for conservative management subject to a "state of metastatic grace" never to be violated. Over the last two decades, conservative management of retinoblastoma witnessed an impressive acceleration of improvements, culminating in two major paradigm shifts in therapeutic strategy. Firstly, the introduction of systemic chemotherapy and focal treatments in the late 1990s enabled radiotherapy to be progressively abandoned. Around 10 years later, the advent of chemotherapy in situ, with the capitalization of new routes of targeted drug delivery, namely intra-arterial, intravitreal and now intracameral injections, allowed significant increase in eye preservation rate, definitive eradication of radiotherapy and reduction of systemic chemotherapy. Here we intend to review the relevant knowledge susceptible to improve the conservative management of retinoblastoma in compliance with the "state of metastatic grace", with particular attention to (i) reviewing how new imaging modalities impact the frontiers of conservative management, (ii) dissecting retinoblastoma genesis, growth patterns, and intraocular routes of tumor propagation, (iii) assessing major therapeutic changes and trends, (iv) proposing a classification of relapsing retinoblastoma, (v) examining treatable/preventable disease-related or treatment-induced complications, and (vi) appraising new therapeutic targets and concepts, as well as liquid biopsy potentiality.

Posterior Vitreous Detachment and the Associated Risk of Retinal Toxicity with Intravitreal Melphalan Treatment for Retinoblastoma

BACKGROUND/AIMS

The presence of a posterior vitreous detachment (PVD) may play a role in the development of severe retinal toxicity following intravitreal melphalan (IVM) injection for vitreous seeding. We aimed to evaluate the incidence of PVD in retinoblastoma eyes and its association with retinal toxicity after IVM.

METHODS

We reviewed 112 eyes of 81 retinoblastoma patients with B-scan images available for review from 2010 to 2017. A cohort with vitreous seeding treated with IVM was compared to a cohort that did not undergo injection. The primary outcome measure was the presence of PVD at diagnosis and after treatment. Secondary measures included IVM-associated retinal toxicity and other ocular complications.

RESULTS

The incidence of PVD was 20% at diagnosis, and in eyes with B-scans available both at diagnosis and after treatment 18% of eyes developed a PVD over the course of therapy, more frequently after IVM (p = 0.05). Of 34 eyes receiving IVM treatment, the incidences of posterior segment toxicity and globe salvage were similar between eyes with and without PVD (p = 0.4015 and 0.52, respectively).

CONCLUSION

In this cohort of patients, there did not appear to be an association with the presence of PVD during IVM and the development of retinal toxicity.

Tridimensional Retinoblastoma Cultures as Vitreous Seeds Models for Live-Cell Imaging of Chemotherapy Penetration

A preclinical model could aid in understanding retinoblastoma vitreous seeds behavior, drug penetration, and response to chemotherapy to optimize patient treatment. Our aim was to develop a tridimensional in vitro model of retinoblastoma vitreous seeds to assess chemotherapy penetration by means of live-cell imaging. Cell cultures from patients with retinoblastoma who underwent upfront enucleation were established and thoroughly characterized for authentication of human tumor origin. The correlation of the in vitro tridimensional structures resembling human spheres and dusts vitreous seeds was established. Confocal microscopy was used to quantify real-time fluorescence of topotecan as a measure of its penetration into different sizes of spheres. Cell viability was determined after chemotherapy penetration. The in vitro spheres and dusts models were able to recapitulate the morphology, phenotype, and genotype of patient vitreous seeds. The larger the size of the spheres, the longer the time required for the drug to fully penetrate into the core (p < 0.05). Importantly, topotecan penetration correlated with its cytotoxic activity. Therefore, the studied tridimensional cell model recapitulated several characteristics of vitreous seeds observed in patients with retinoblastoma and were successfully used to assess live-cell imaging of chemotherapy penetration for drug distribution studies.

Ocular toxicity of intravitreal melphalan for retinoblastoma in Chinese patients

Background

To evaluate the efficacy, complications, and clinical characteristics, including the ocular toxicity, of intravitreal melphalan(IVM) treatment for vitreous seeding in Chinese retinoblastoma patients.

Methods

This was a retrospective, non-comparative analysis including 30 consecutive eyes of 23 patients with viable persistent or recurrent vitreous seeding following retinoblastoma treatment. All of the eyes received IVM injections (20–33 μg). Vitreous seeding control, determination of the ocular toxicity, and the clinical characteristics of intravitreal melphalan treatments were observed.

Results

The mean patient age at the time of the injection was 28 months (median = 22 months, range = 12–50 months). In total, 80 injections were administered in 30 eyes, the overall enucleation-free survival rate was 83.3% (25/30). The complications included retinal pigment epithelium (RPE) and choroidal atrophy (19/30, 63.3%), pupillary synechiae (13/30, 43.3%), iris atrophy (12/30, 40%), retinal vascular occlusion (12/30, 40.0%), optic atrophy (6/30, 20%), vitreous hemorrhage (3/30, 10%), persistent hypotonia and phthisis bulbi (4/30 13.3%), and cataracts (8/30, 26.6%). Twelve eyes demonstrated grade 3 or greater IVM-associated retinal or anterior segment toxicity post injection. Mean dosage given showed significant difference between the groups. There were no significant differences in the retinal toxicity grades regarding the seed classification or seed regression patterns.

Conclusions

Intravitreal melphalan is an effective treatment for refractory vitreous seeding from retinoblastoma, but exhibits both anterior and posterior segment toxicity in Chinese patients.

Outcomes of Proton Beam Radiation Therapy for Retinoblastoma With Vitreous Seeds

Vitreous seeds are the most challenging aspect in the management of retinoblastoma. We report the outcomes of treatment with proton beam radiation therapy (PBRT) for retinoblastoma with vitreous seeds in naive or previously treated eyes. In this retrospective case series, we analyzed data of 4 retinoblastoma patients with vitreous seeds who received PBRT at the Proton Therapy Center, National Cancer Center in Korea between June 2007 and August 2017. All 4 eyes treated by PBRT were classified as group D according to the International Classification of Retinoblastoma (ICRB) criteria, and the vitreous seeds, as class 3 (clouds). The tumor and vitreous seeds regressed in 2 eyes, and globe salvage was achieved in these 2 eyes (50%). The post-PBRT ophthalmologic follow-up time of these 2 preserved eyes was 12 and 50 months, respectively. Visual acuity measurements of the successfully treated patients were 20/40 and 20/600. No radiation-associated malignancies were noted. In conclusion, PBRT successfully treated vitreous seeds classified as clouds in half of the cases, and successfully treated patients who retained useful vision. Therefore, PBRT might be a viable treatment option for vitreous seeds in patients with retinoblastoma.

A three-dimensional organoid model recapitulates tumorigenic aspects and drug responses of advanced human retinoblastoma

Persistent or recurrent retinoblastoma (RB) is associated with the presence of vitreous or/and subretinal seeds in advanced RB and represents a major cause of therapeutic failure. This necessitates the development of novel therapies and thus requires a model of advanced RB for testing candidate therapeutics. To this aim, we established and characterized a three-dimensional, self-organizing organoid model derived from chemotherapy-naïve tumors. The responses of organoids to drugs were determined and compared to relate organoid model to advanced RB, in terms of drug sensitivities. We found that organoids had histological features resembling retinal tumors and seeds and retained DNA copy-number alterations as well as gene and protein expression of the parental tissue. Cone signal circuitry (M/L⁺ cells) and glial tumor microenvironment (GFAP⁺ cells) were primarily present in organoids. Topotecan alone or the combined drug regimen of topotecan and melphalan effectively targeted proliferative tumor cones (RXRγ⁺ Ki67⁺) in organoids after 24-h drug exposure, blocking mitotic entry. In contrast, methotrexate showed the least efficacy against tumor cells. The drug responses of organoids were consistent with those of tumor cells in advanced disease. Patient-derived organoids enable the creation of a faithful model to use in examining novel therapeutics for RB.

Genomic cfDNA Analysis of Aqueous Humor in Retinoblastoma Predicts Eye Salvage: The Surrogate Tumor Biopsy for Retinoblastoma

Tumor-derived cell-free DNA (cfDNA) has biomarker potential; therefore, this study aimed to identify cfDNA in the aqueous humor (AH) of retinoblastoma eyes and correlate somatic chromosomal copy-number alterations (SCNA) with clinical outcomes, specifically eye salvage. AH was extracted via paracentesis during intravitreal injection of chemotherapy or enucleation. Shallow whole-genome sequencing was performed using isolated cfDNA to assess for highly recurrent SCNAs in retinoblastoma including gain of 1q, 2p, 6p, loss of 13q, 16q, and focal MYCN amplification. Sixty-three clinical specimens of AH from 29 eyes of 26 patients were evaluated; 13 eyes were enucleated and 16 were salvaged (e.g., saved). The presence of detectable SCNAs was 92% in enucleated eyes versus 38% in salvaged eyes (P = 0.006). Gain of chromosome 6p was the most common SCNA found in 77% of enucleated eyes, compared with 25% of salvaged eyes (P = 0.0092), and associated with a 10-fold increased odds of enucleation (OR, 10; 95% CI, 1.8-55.6). The median amplitude of 6p gain was 1.47 in enucleated versus 1.07 in salvaged eyes (P = 0.001). The presence of AH SCNAs was correlated retrospectively with eye salvage. The probability of ocular salvage was higher in eyes without detectable SCNAs in the AH (P = 0.0028), specifically 6p gain. This is the first study to correlate clinical outcomes with SCNAs in the AH from retinoblastoma eyes, as such these findings indicate that 6p gain in the aqueous humor is a potential prognostic biomarker for poor clinical response to therapy.Implications: The correlation of clinical outcomes and SCNAs in the AH identified in the current study requires prospective studies to validate these finding before SCNAs, like 6p gain, can be used to predict clinical outcomes at diagnosis. Mol Cancer Res; 16(11); 1701-12. ©2018 AACR.

Integrated Treatment during the Intravitreal Melphalan Era: Concurrent Intravitreal Melphalan and Systemic Chemoreduction

Background

Intravitreal injection of melphalan (IVM) is safe and effective for the treatment of seeding in retinoblastoma. Current protocols require weekly injections during examination under anesthesia (EUA). To avoid additional anesthesia exposure for these children, IVM was initiated at the EUA concurrent with the 4th cycle of systemic chemoreduction in a series of 6 patients with persistent seeding.

Methods

A retrospective review was completed to assess treatment response compared to all patients at our center treated with IVM and systemic chemotherapy. Overall, 6 eyes of 6 patients were included; salvage therapy included systemic chemoreduction with vincristine, etoposide, and carboplatin and IVM for persistent seeding.

Results

IVM was initiated in all eyes at cycle 4 of their chemotherapy. Success in eradicating vitreous seeds was 100%; overall salvage rate was 67%. Anterior toxicity was observed in 2 out of 6 eyes and posterior toxicity in 4 out of 6 eyes.

Conclusion

The concurrent chemoreduction and IVM protocol demonstrated a similar efficacy of globe salvage while sparing children additional EUAs. However, the increased rates of observed melphalan-related toxicities for concurrent therapy are concerning. Further clinical experience is necessary to define the best initiation time and dosing schedule for IVM.