Advancements in Nanosystems for Ocular Drug Delivery: A Focus on Pediatric Retinoblastoma.

The eye's complex anatomical structures present formidable barriers to effective drug delivery across a range of ocular diseases, from anterior to posterior segment pathologies. Emerging as a promising solution to these challenges, nanotechnology-based platforms-including but not limited to liposomes, dendrimers, and micelles-have shown the potential to revolutionize ophthalmic therapeutics. These nanocarriers enhance drug bioavailability, increase residence time in targeted ocular tissues, and offer precise, localized delivery, minimizing systemic side effects. Focusing on pediatric ophthalmology, particularly on retinoblastoma, this review delves into the recent advancements in functionalized nanosystems for drug delivery. Covering the literature from 2017 to 2023, it comprehensively examines these nanocarriers' potential impact on transforming the treatment landscape for retinoblastoma. The review highlights the critical role of these platforms in overcoming the unique pediatric eye barriers, thus enhancing treatment efficacy. It underscores the necessity for ongoing research to realize the full clinical potential of these innovative drug delivery systems in pediatric ophthalmology.

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.

Therapy for Vitreous Seeding Caused by Retinoblastoma. A Review.

Retinoblastoma is the most common primary malignant intraocular tumor in children. Seeding, specifically the dispersion of the tumor into the adjacent compartments, represents a major parameter determining the degree of retinoblastoma according to the International Classification of Retinoblastoma. In this article we focused on vitreous seeding, one of the main limiting factors in the successful "eye preservation treatment" of retinoblastoma. This article presents an overview of the history of vitreous seeding of retinoblastoma, established treatment procedures and new-research modalities. The introduction of systemic chemotherapy in the treatment of retinoblastoma at the end of the 1990s represented a significant breakthrough, which enabled the progressive abandonment of radiotherapy with its attendant side effects. However, the attained concentrations of chemotherapeutics in the vitreous space during systemic chemotherapy are not sufficient for the treatment of vitreous seeding, and the toxic effects of systemic chemotherapy are not negligible. A significant change came with the advent of chemotherapy in situ, with the targeted administration of chemotherapeutic drugs, namely intra-arterial and intravitreal injections, contributing to the definitive eradication of external radiotherapy and a reduction of systemic chemotherapy. Although vitreous seeding remains the most common reason for the failure of intra-arterial chemotherapy, this technique has significantly influenced the original treatment regimen of children with retinoblastoma. However, intravitreal chemotherapy has made the greatest contribution to increasing the probability of preservation of the eyeball and visual functions in patients with advanced findings. Novel local drug delivery modalities, gene therapy, oncolytic viruses and immunotherapy from several ongoing preclinical and clinical trials may represent promising approaches in the treatment of vitreous retinoblastoma seeding, though no clinical trials have yet been completed for routine use.

Advanced Interventional Treatments in Retinoblastoma Management: A Comprehensive Review.

Retinoblastoma is the most common eye malignancy in children that if left untreated can invade intraocular structures, metastasize, and rarely lead to death. Traditionally treated with systemic chemotherapy, Intra-arterial chemotherapy is gaining popularity as it allows for the direct administration of chemotherapy through the ophthalmic artery, thus reducing systemic side effects. Intra-arterial chemotherapy procedures have evolved, with refinements to reduce risks and radiation exposure. Intra-arterial chemotherapy boasts an impressive technical success rate and one year ocular survival even amongst advanced cases. This review offers a thorough examination of the technique, indications, contraindications, outcomes, and alternative options for Intra-arterial chemotherapy.

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.

Circulating Tumor DNA Posttreatment Measurements and Clinical Correlates in Retinoblastoma.

Importance: Plasma measurements of RB1 circulating tumor DNA (ctDNA) after completion of treatment may be associated with the development of metastases in patients with retinoblastoma. Objective: To determine if the absence of previously detectable plasma ctDNA is associated with metastasis-free survival in patients with a minimum of 1 year follow-up after treatment of retinoblastoma. Design, Setting, and Participants: This cohort study was conducted from June 2019 to September 2023. Patients with retinoblastoma who had measurable ctDNA levels at diagnosis and had repeated ctDNA measurements after ocular treatment (enucleation or intra-arterial chemotherapy) with a minimum of 1 year of follow-up (mean [SD], 28.2 [10.3] months) were included in the study. Patients were recruited from a single-center, tertiary cancer hospital. Exposure: Memorial Sloan Kettering's New York State-approved gene test, which interrogates 129 known cancer genes (called ACCESS), was performed on plasma samples before and after ocular treatments. All exons of the RB1 gene are included in the test and listed as ctDNA in this article. Main Outcomes and Measures: Plasma ctDNA level before treatment, after completion of ocular treatment, and development or absence of metastases. Results: A total of 24 patients (mean [SD] age, 20.7 [17.1] months; 15 female [62.5%]) were included in the study. None of the 23 patients who had a measurable ctDNA level and then no detectable ctDNA level after completion of ocular treatment developed metastases with a minimum of 1 year of follow-up. One patient had persistent measurable ctDNA after initial treatment and developed metastases. Conclusion and Relevance: Patients with retinoblastoma who had a measurable ctDNA level at diagnosis did not develop metastases if the plasma ctDNA level became unrecordable after ocular treatment; 1 patient who had persistent measurable ctDNA after treatment did develop metastasis.

Joint CB1 and NGF Receptor Activation Suppresses TRPM8 Activation in Etoposide-Resistant Retinoblastoma Cells.

In childhood, retinoblastoma (RB) is the most common primary tumor in the eye. Long term therapeutic management with etoposide of this life-threatening condition may have diminishing effectiveness since RB cells can develop cytostatic resistance to this drug. To determine whether changes in receptor-mediated control of Ca2+ signaling are associated with resistance development, fluorescence calcium imaging, semi-quantitative RT-qPCR analyses, and trypan blue dye exclusion staining patterns are compared in WERI-ETOR (etoposide-insensitive) and WERI-Rb1 (etoposide-sensitive) cells. The cannabinoid receptor agonist 1 (CNR1) WIN55,212-2 (40 µM), or the transient receptor potential melastatin 8 (TRPM8) agonist icilin (40 µM) elicit similar large Ca2+ transients in both cell line types. On the other hand, NGF (100 ng/mL) induces larger rises in WERI-ETOR cells than in WERI-Rb1 cells, and its lethality is larger in WERI-Rb1 cells than in WERI-ETOR cells. NGF and WIN55,212-2 induced additive Ca2+ transients in both cell types. However, following pretreatment with both NGF and WIN55,212-2, TRPM8 gene expression declines and icilin-induced Ca2+ transients are completely blocked only in WERI-ETOR cells. Furthermore, CNR1 gene expression levels are larger in WERI-ETOR cells than those in WERI-Rb1 cells. Therefore, the development of etoposide insensitivity may be associated with rises in CNR1 gene expression, which in turn suppress TRPM8 gene expression through crosstalk.

Antitumoral Potential of the Histone Demethylase Inhibitor GSK-J4 in Retinoblastoma.

Purpose: The purpose of this study was to investigate the antitumor effects of GSK-J4 on retinoblastoma, as well as its related biological functions and molecular mechanisms. Methods: The antitumor effect of GSK-J4 on retinoblastoma was evaluated by in vitro and in vivo assays. CCK-8, EdU incorporation, and soft agar colony formation assays were performed to examine the effect of GSK-J4 on cell proliferation. Flow cytometry was used to evaluate the effect of GSK-J4 on the cell cycle and apoptosis. RNA-seq and Western blotting were conducted to explore the molecular mechanisms of GSK-J4. An orthotopic xenograft model was established to determine the effect of GSK-J4 on tumor growth. Results: GSK-J4 significantly inhibited retinoblastoma cell proliferation both in vitro and in vivo, arrested the cell cycle at G2/M phase, and induced apoptosis. Mechanistically, GSK-J4 may suppress retinoblastoma cell growth by regulating the PI3K/AKT/NF-κB signaling pathway. Conclusions: The antitumor effects of GSK-J4 were noticeable in retinoblastoma and were at least partially mediated by PI3K/AKT/NF-κB pathway suppression. Our study provides a novel strategy for the treatment of retinoblastoma.

New retinoblastoma (RB) drug delivery approaches: anti-tumor effect of atrial natriuretic peptide (ANP)-conjugated hyaluronic-acid-coated gold nanoparticles for intraocular treatment of chemoresistant RB.

Intraocular drug delivery is a promising approach for treatment of ocular diseases. Chemotherapeutic drugs used in retinoblastoma (RB) treatment often lead to side effects and drug resistances. Therefore, new adjuvant therapies are needed to treat chemoresistant RBs. Biocompatible gold nanoparticles (GNPs) have unique antiangiogenic properties and can inhibit cancer progression. The combination of gold and low-molecular-weight hyaluronan (HA) enhances the stability of GNPs and promotes the distribution across ocular barriers. Attached to HA-GNPs, the atrial natriuretic peptide (ANP), which diminishes neovascularization in the eye, is a promising new therapeutic agent for RB treatment. In the study presented, we established ANP-coupled HA-GNPs and investigated their effect on the tumor formation potential of chemoresistant RB cells in an in ovo chicken chorioallantoic membrane model and an orthotopic in vivo RB rat eye model. Treatment of etoposide-resistant RB cells with ANP-HA-GNPs in ovo resulted in significantly reduced tumor growth and angiogenesis compared with controls. The antitumorigenic effect could be verified in the rat eye model, including a noninvasive application form via eye drops. Our data suggest that ANP-HA-GNPs represent a new minimally invasive, adjuvant treatment option for RB.

Prox1 Suppresses Proliferation and Drug Resistance of Retinoblastoma Cells via Targeting Notch1.

OBJECTIVE: Retinoblastoma (RB) is a prevalent type of eye cancer in youngsters. Prospero homeobox 1 (Prox1) is a homeobox transcriptional repressor and downstream target of the proneural gene that is relevant in lymphatic, hepatocyte, pancreatic, heart, lens, retinal, and cancer cells. The goal of this study was to investigate the role of Prox1 in RB cell proliferation and drug resistance, as well as to explore the underlying Notch1 mechanism. METHODS: Human RB cell lines (SO-RB50 and Y79) and a primary human retinal microvascular endothelial cell line (ACBRI-181) were used in this study. The expression of Prox1 and Notch1 mRNA and protein in RB cells was detected using quantitative real time-polymerase chain reaction (RT-qPCR) and Western blotting. Cell proliferation was assessed after Prox1 overexpression using the Cell Counting Kit-8 and the MTS assay. Drug-resistant cell lines (SO-RB50/vincristine) were generated and treated with Prox1 to investigate the role of Prox1 in drug resistance. We employed pcDNA-Notch1 to overexpress Notch1 to confirm the role of Notch1 in the protective function of Prox1. Finally, a xenograft model was constructed to assess the effect of Prox1 on RB in vivo. RESULTS: Prox1 was significantly downregulated in RB cells. Overexpression of Prox1 effectively decreased RB cell growth while increasing the sensitivity of drug-resistant cells to vincristine. Notch1 was involved in Prox1's regulatory effects. Notch1 was identified as a target gene of Prox1, which was found to be upregulated in RB cells and repressed by increased Prox1 expression. When pcDNA-Notch1 was transfected, the effect of Prox1 overexpression on RB was removed. Furthermore, by downregulating Notch1, Prox1 overexpression slowed tumor development and increased vincristine sensitivity in vivo. CONCLUSION: These data show that Prox1 decreased RB cell proliferation and drug resistance by targeting Notch1, implying that Prox1 could be a potential therapeutic target for RB.

SECONDARY SALVAGE INTRAVENOUS CHEMOTHERAPY FOR REFRACTORY/RECURRENT RETINOBLASTOMA: A Study of 41 Eyes.

PURPOSE: To determine the efficacy of secondary salvage intravenous chemotherapy (IVC) for refractory/recurrent retinoblastoma. METHODS: Retrospective, nonrandomized interventional case series of 41 eyes of 33 patients with recurrent retinoblastoma. RESULTS: Of the 33 patients, mean age at the time of commencement of salvage IVC was 5 years (median, 5 years; range, 2-8 years). At presentation, recurrent retinoblastoma in 41 eyes of 33 patients was classified by the International Classification of Retinoblastoma as Group B (n = 7; 17%), Group C (n = 3; 7%), Group D (n = 16; 39%), and Group E (n = 15; 37%). All patients received 6 cycles of IVC as primary treatment. The indication for secondary salvage IVC with focal treatment included recurrent solid tumor (n = 36; 88%), subretinal seeds (n = 22; 54%), or persistent solid tumor (n = 2; 5%). Mean number of cycles of salvage IVC were 8 (median, 6; range, 6-18). Over a mean follow-up period of 43 months (median, 43 months; range, 12-96 months) after completion of salvage IVC, globe salvage was achieved in 22 (54%) eyes, 1 (3%) patient had histopathology-proven bone metastasis, and 1 (3%) patient died because of presumed metastasis. CONCLUSION: Secondary salvage IVC with appropriate focal treatment allows globe salvage in 54% eyes with refractory/recurrent retinoblastoma and thus serves as an alternative to intraarterial chemotherapy or enucleation.

Gentiopicroside inhibits retinoblastoma cell proliferation, invasion, and tumorigenesis in nude mice by suppressing the PI3K/AKT pathway.

Retinoblastoma is a prevalent pediatric intraocular tumor. The suppressive effect of gentiopicroside (GPS) has been reported on various tumors. This study sought to determine the effect of GPS on retinoblastoma cell proliferation, apoptosis, invasion, and epithelial-mesenchymal transition (EMT), and tumorigenesis in nude mice. The effect and mechanism of GPS on growth, apoptosis, invasion, and EMT were determined by cell counting kit-8 (CCK-8), western blot, flow cytometry, and transwell assays in retinoblastoma cells. Y79 cells were injected into the vitreous cavity of BALB/c­nude mice to construct a retinoblastoma mouse model. Tumor growth and mouse weight were monitored for sequential 5 weeks. The effect of GPS in vivo was assessed by immunohistochemistry (IHC), terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL), and western blot assays. GPS decreased the cell viability of both Y79 and Weri-Rb1 cells with the IC50 of 18.85 µM and 27.57 µM, respectively. Besides, GPS reduced the relative expression of proteins involved in proliferation and EMT, and the number of invading cells, while increased the apoptosis rate and the relative expressions of apoptosis proteins in retinoblastoma cells. Mechanically, GPS decreased the relative protein level of PI3K/AKT pathway, which was then recovered after 740 Y-P was applied. Correspondingly, 740 Y-P reversed the inhibitory effect of GPS on growth, invasion, and EMT, and the increased effect of GPS on apoptosis. Additionally, GPS decreased tumor volume and weight as well as the relative level of Ki-67, VEGF, p-PI3K/PI3K, and p-AKT/AKT, while increased the apoptosis rate in vivo. GPS inhibited retinoblastoma cell proliferation and invasion via deactivating the PI3K/AKT pathway in both cell and animal models.

Advancements in super-selective catheterization and drug selection for intra-arterial chemotherapy for retinoblastoma: a 15-year evolution.

BACKGROUND: Retinoblastoma (Rb) is the most common primary ocular malignancy of childhood. Left untreated, it is 100% fatal and carries a substantial risk of impaired vision and removal of one or both eyes. Intra-arterial chemotherapy (IAC) has become a pillar in the treatment paradigm for Rb that allows for better eye salvage and vision preservation without compromising survival. We describe the evolution of our technique over 15 years. METHODS: A retrospective chart review was conducted of 571 patients (697 eyes) and 2391 successful IAC sessions over 15 years. This cohort was separated into three 5-year periods (P1, P2, P3) to assess trends in IAC catheterization technique, complications, and drug delivery. RESULTS: From a total of 2402 attempted IAC sessions, there were 2391 successful IAC deliveries, consistent with a 99.5% success rate. The rate of successful super-selective catheterizations over the three periods ranged from 80% in P1 to 84.9% in P2 and 89.2% in P3. Catheterization-related complication rates were 0.7% in P1, 1.1% in P2, and 0.6% in P3. Chemotherapeutics used included combinations of melphalan, topotecan and carboplatin. The rate of patients receiving triple therapy among all groups was 128 (21%) in P1, 487 (41.9%) in P2, and 413 (66.7%) in P3. CONCLUSIONS: The overall rate of successful catheterization and IAC started high and has improved over 15 years, and catheterization-related complications are rare. There has been a significant trend towards triple chemotherapy over time.

Efficacy of intravitreal injections of melphalan in the treatment of retinoblastoma vitreous seeding.

BACKGROUND: The introduction of intravitreal injections of melphalan (IVIM) has significantly improved the efficacy of retinoblastoma treatment and the prognosis for eye preservation. OBJECTIVES: To evaluate the results of using IVIM to treat retinoblastoma vitreous seeding. MATERIAL AND METHODS: This was a clinical, retrospective, single-center study. Twenty-six children (27 eyes) who met all of the following inclusion criteria qualified for the study: 1) active vitreous seeding at the time of retinoblastoma diagnosis; 2) IVIM performed between 1 January 2017 and 30 September 2020; and 3) a minimum follow-up period of 12 months since the last IVIM. Doses of 20-40 µg melphalan per injection were used. RESULTS: The eye observation period from the last IVIM to the last ophthalmic examination averaged 32.41 months (median 30.00; range 13.00-56.00). Success (no active tumors in the vitreous body) was achieved in 24 eyes (88.9%), and a doubtful result (recurrence in the retina with a difficult-to-determine etiology) in 2 eyes (7.4%). In 1 eye (3.7%), despite treatment, active tumors were still present in the vitreous body. Out of all 27 eyes, 4 eyeballs were removed, but the direct cause of enucleation was not vitreous seeding. There were no complications in the form of intraocular inflammation, extraocular retinoblastoma or distant metastases. There was 1 case of anterior uveitis and 1 case of cataract. CONCLUSIONS: The IVIM is a highly effective and safe form of treatment for retinoblastoma vitreous seeding.

Ceftriaxone exerts antitumor effects in MYCN-driven retinoblastoma and neuroblastoma by targeting DDX3X for translation repression.

MYCN proto-oncogene, bHLH transcription factor (MYCN) amplification is associated with aggressive retinoblastoma (RB) and neuroblastoma (NB) cancer recurrence that is resistant to chemotherapies. Therefore, there is an urgent need to identify new therapeutic tools. This study aimed to evaluate the potential repurposing of ceftriaxone for the treatment of MYCN-amplified RB and NB, based on the clinical observations that the drug was serendipitously found to decrease the volume of the MYCN-driven RB subtype. Using patient-derived tumor organoids and tumor cell lines, we demonstrated that ceftriaxone is a potent and selective growth inhibitor targeting MYCN-driven RB and NB cells. Profiling of drug-induced transcriptomic changes, cell-cycle progression, and apoptotic death indicated cell-cycle arrest and death of drug-treated MYCN-amplified tumor cells. Drug target identification, using an affinity-based proteomic and molecular docking approach, and functional studies of the target proteins revealed that ceftriaxone targeted DEAD-box helicase 3 X-linked (DDX3X), thereby inhibiting translation in MYCN-amplified tumors but not in MYCN-nonamplified cells. The data suggest the feasibility of repurposing ceftriaxone as an anticancer drug and provide insights into the mechanism of drug action, highlighting DDX3X as a potential target for treating MYCN-driven tumors.

Conservative treatment using laser diode and systemic chemotherapy for early-stage bilateral retinoblastoma: A 14-year prospective cohort study.

BACKGROUND: Solid evidence of the safety and effectiveness of retinoblastoma (RB) conservative treatment using thermotherapy and systemic chemotherapy with long-term follow-up is scarce, especially in low-resource countries. AIMS: This study examined the outcomes of this treatment and associated predictors in Vietnam to strengthen the current RB treatment protocol focusing on preserving eye and vision in low-resource settings. METHODS AND RESULTS: A prospective cohort study was conducted at Ho Chi Minh City Eye Hospital in Vietnam from 2005 to 2019. All eligible patients with bilateral RB (one eye already removed and another eye classified as group A or B) and without previous treatment were recruited. All patients received thermotherapy and six cycles of systemic three-agent chemotherapy repeated every 4 weeks. A standardized questionnaire was used to collect information on study participants' age, symptoms, tumor characteristics, treatment, and outcomes. Among 50 eyes of all 50 patients with a median age of 9 (4-20) months, 34 eyes were in group B (68%). The median follow-up time was 60 (60-84) months. All 139 preserved tumors regressed mostly to type 4 (70.4%) and type 3 (23.7%) scars. Kaplan-Meier analysis found the overall globe-salvage rate at 5 years of 91.9% (95% CI: 80.1%-97.7%). Most eyes (41/50, 82%, 95% CI: 69.2%-90.2%) had a final visual acuity ≥0.1. The visual acuity is higher when tumors regressed to a type 4 scar (p = .007, AOR = 8.098, 95% CI: 1.79-36.53) which also shows less enucleation than a type 3 scar (p = .002, AOR = 0.06, 95% CI: 0.01-0.37%). Gender effect on visual acuity after treatment was significant and may be due to discrimination. No major complications were recorded. CONCLUSION: Conservative treatment of early-stage RB is safe and effective. Long-term, thorough follow-ups of patients post-treatment are needed. The regression patterns of scars could be a useful indicator of treatment failure.

Angiographic characteristics and treatment approach in patients undergoing intra-arterial chemotherapy for retinoblastoma.

PURPOSE: To identify the specific clinical and angiographic variables that determine the success of intra-arterial chemotherapy (IAC) in a patient with retinoblastoma. METHODS: Medical records from patients undergoing intra-arterial chemotherapy for the treatment of retinoblastoma between January 2015 and June 2020 within a large academic ocular oncology practice were retrospectively reviewed. Demographics were recorded together with clinical, ocular, and angiographic variables such as the diameter of the ophthalmic artery (OA), angle of ophthalmic artery takeoff, and branching pattern of ophthalmic vasculature. RESULTS: Forty-four eyes from 33 patients with retinoblastoma treated with IAC were identified. Over the total 32 mean months of follow-up, these patients received 144 total catheterizations and a mean of 3.2 IAC cycles for each eye. The number of IAC cycles and the chemotherapeutic agent used did not vary significantly with worsening International Classification of Retinoblastoma (ICRB) groups (P > 0.1). Cumulative dose did not vary with the ICRB group for eyes treated with melphalan, topotecan, or carboplatin (P > 0.1). A higher ICRB group was associated with a smaller mean ophthalmic artery diameter across all procedures (P = 0.016), and femoral artery diameter did not vary significantly between ICRB groups (P = 0.906). A higher cumulative dose of IAC was significantly associated with a smaller takeoff angle of the OA (melphalan, P = 0.011; topotecan, P = 0.009; carboplatin, P = 0.031) in patients who underwent successful IAC procedures. Ophthalmic artery diameter and femoral artery diameter did not have a significant association (P > 0.1) with higher IAC doses in successful IACs. Cumulative IAC dose was not significantly associated with ophthalmic vasculature branching pattern, presence of choroidal blush, temporary OA vasospasm reported during the procedure, and OA occlusion upon microcatheter placement. CONCLUSION: In this study, neurosurgical angioanatomy appeared to influence the cumulative dose of chemotherapy needed during IAC for retinoblastoma. In the future, these anatomic variables may be used to guide the frequency of monitoring, dosing, and estimation of recurrence risk.