Aqueous seeding in intraocular retinoblastoma: A review

An anti-GD2 aptamer-based bifunctional spherical nucleic acid nanoplatform for synergistic therapy targeting MDM2 for retinoblastoma

Retinoblastoma (RB) is a type of pediatric solid tumor in the fundus. The lack of precision therapies combined with the difficulty of delivering small interfering RNA (siRNA) into the eyes means that there is currently no nucleic acid-based therapy for RB in clinical practice. Here, we reported on anti-GD2 and glutathione-responsive spherical nucleic acids (SNAs), loaded with siRNA and the inhibitor NVP-CGM097, which jointly blocked the oncogenic factor n in RB cells (Y79 and WERI-RB-1). The SNAs were formed through the self-assembly of bifunctional cholesterol amphiphiles containing aptamers that specifically targeted GD2-positive RB cells, allowing for the formation of an SNA with a dense DNA shell. The aptamer/siRNA component functioned both as a carrier and a payload, enhancing the specific recognition and delivery of both components and constituting an active agent for MDM2 regulation. Following SNA endocytosis by RB cells, siRNA and NVP-CGM097 were released from the SNA particles by glutathione, which synergistically blocked the MDM2-p53 pathway, increasing p53 protein content and inducing cell apoptosis. This study showed a potent antitumor effect following intravitreal injection of SNAs in Y79 tumor-bearing mice through clinical manifestation and tumor pathological analysis. In hematological analysis and hepatotoxicity assays, SNAs were safer for mice than melphalan, the favored drug for treating RB in clinical practice. Our results illustrated the potential of intravitreally injected SNAs as a precision medicine for treating RB.

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.

Ten-year experience with intracameral chemotherapy for aqueous seeding in retinoblastoma: long-term efficacy, safety and toxicity

AIMS

To report long-term results of intracameral chemotherapy (ICC) for aqueous seeding (AS) in retinoblastoma.

METHODS

Retrospective study including 20 patients with primary (n=4) or secondary non-iatrogenic (n=16) AS treated with ICC according to a previously described technique between 2011 and 2020 with at least 1-year follow-up.

RESULTS

AS control was initially achieved in all cases with a mean 5 injections of melphalan (n=13) or topotecan (n=7). Three eyes had an isolated AS relapse at a mean interval of 8 months after the first ICC course, which regressed with a second course of intracameral melphalan. Concomitant interciliary process seed implantation was treated with additional brachytherapy if sectorial (n=3) or proton therapy if annular (n=1). Other therapies including systemic, intra-arterial chemotherapy and/or focal treatments were given in 15 eyes to treat concomitant tumour sites. Eye preservation was achieved in 85% of the eyes (n=17/20) at a mean event-free follow-up of 45 months for aqueous disease, and 40 months for any other intraocular tumour activity. Three cases were enucleated due to refractory non-aqueous disease. All patients are alive without metastasis (mean follow-up of 48 months after first ICC). ICC-related intraocular toxicity included iris atrophy (n=5), cataract (n=4), posterior synechiae (n=2) and iris heterochromia (n=1). No patient suffered irreversible vision loss. Useful to normal vision was found in 82% of the cases (n=14/17).

CONCLUSION

ICC appears to be safe and efficient for AS without irreversible vision-threatening adverse effects. More data are needed to determine any superiority in efficiency/toxicity of topotecan versus melphalan.

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.

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.

Defining High-Risk Retinoblastoma: A Multicenter Global Survey

Importance

High-risk histopathologic features of retinoblastoma are useful to assess the risk of systemic metastasis. In this era of globe salvage treatments for retinoblastoma, the definition of high-risk retinoblastoma is evolving.

Objective

To evaluate variations in the definition of high-risk histopathologic features for metastasis of retinoblastoma in different ocular oncology practices around the world.

Design, Setting, and Participants

An electronic web-based, nonvalidated 10-question survey was sent in December 2020 to 52 oncologists and pathologists treating retinoblastoma at referral retinoblastoma centers.

Intervention

Anonymized survey about the definition of high-risk histopathologic features for metastasis of retinoblastoma.

Main Outcomes and Measures

High-risk histopathologic features that determine further treatment with adjuvant systemic chemotherapy to prevent metastasis.

Results

Among the 52 survey recipients, the results are based on the responses from 27 individuals (52%) from 24 different retinoblastoma practices across 16 countries in 6 continents. The following were considered to be high-risk features: postlaminar optic nerve infiltration (27 [100%]), involvement of optic nerve transection (27 [100%]), extrascleral tissue infiltration (27 [100%]), massive (≥3 mm) choroidal invasion (25 [93%]), microscopic scleral infiltration (23 [85%]), ciliary body infiltration (20 [74%]), trabecular meshwork invasion (18 [67%]), iris infiltration (17 [63%]), anterior chamber seeds (14 [52%]), laminar optic nerve infiltration (13 [48%]), combination of prelaminar and laminar optic nerve infiltration and minor choroidal invasion (11 [41%]), minor (<3 mm) choroidal invasion (5 [19%]), and prelaminar optic nerve infiltration (2 [7%]). The other histopathologic features considered high risk included Schlemm canal invasion (4 [15%]) and severe anaplasia (1 [4%]). Four respondents (15%) said that the presence of more than 1 high-risk feature, especially a combination of massive peripapillary choroidal invasion and postlaminar optic nerve infiltration, should be considered very high risk for metastasis.

Conclusions and Relevance

Responses to this nonvalidated survey conducted in 2020-2021 showed little uniformity in the definition of high-risk retinoblastoma. Postlaminar optic nerve infiltration, involvement of optic nerve transection, and extrascleral tumor extension were the only features uniformly considered as high risk for metastasis across all oncology practices. These findings suggest that the relevance about their value in the current scenario with advanced disease being treated conservatively needs further evaluation; there is also a need to arrive at consensus definitions and conduct prospective multicenter studies to understand their relevance.