Orbital Swelling in a Child With Retinoblastoma Following Intra-arterial Chemotherapy

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.

Efficacy, Toxicity, and Pharmacokinetics of Intra-Arterial Chemotherapy Versus Intravenous Chemotherapy for Retinoblastoma in Animal Models and Patients

Purpose

Through controlled comparative rabbit experiments and parallel patient studies, our purpose was to understand mechanisms underlying differences in efficacy and toxicity between intra-arterial chemotherapy (IAC) and intravenous chemotherapy (IVC).

Methods

In rabbits, ocular tissue drug levels were measured following IAC and IVC. Retinal toxicity was assessed using electroretinography, fluorescein angiography, optical coherence tomography (OCT) and OCT angiography. Efficacy to eradicate retinoblastoma orthotopic xenografts was compared. In IAC and IVC patients, we measured blood carboplatin pharmacokinetics and compared efficacy and toxicity.

Results

In rabbits receiving IAC, maximum carboplatin levels were 134 times greater in retina (P = 0.01) and 411 times greater in vitreous (P < 0.001), and total carboplatin (area under the curve) was 123 times greater in retina (P = 0.005) and 131 times greater in vitreous (P = 0.02) compared with IVC. Melphalan levels were 12 times greater (P = 0.003) in retina and 26 times greater in vitreous (P < 0.001) for IAC. Blood levels were not different. IAC melphalan (but not IV melphalan or IV carboplatin, etoposide, and vincristine) caused widespread apoptosis in retinoblastoma xenografts but no functional retinal toxicity or cytopenias. In patients, blood levels following IVC were greater (P < 0.001) but, when adjusted for treatment dose, were not statistically different. Per treatment cycle in patients, IVC caused higher rates of anemia (0.32 ± 0.29 vs. 0.01 ± 0.04; P = 0.0086), thrombocytopenia (0.5 ± 0.42 vs. 0.0 ± 0.0; P = 0.0042), and neutropenia (0.58 ± 0.3 vs. 0.31 ± 0.25; P = 0.032) but lower treatment success rates (P = 0.0017).

Conclusions

The greater efficacy and lower systemic toxicity with IAC appear to be attributable to the greater ocular-to-systemic drug concentration ratio compared with IVC.

Translational Relevance

Provides an overarching hypothesis for a mechanism of efficacy/toxicity to guide future drug development.

Intra-arterial Chemotherapy as Primary Treatment for Cavitary Retinoblastoma: Excellent Response in Eight Tumors

PURPOSE

The "cavitary" form of retinoblastoma has historically demonstrated minimal treatment response with intravenous chemoreduction, showing less robust regression and less reduction in tumor size. Intra-arterial chemotherapy (IAC) has been reported to more effectively treat retinoblastoma, allowing many previously unsalvageable eyes to now be saved. The purpose was to report treatment response of cavitary retinoblastoma tumors to IAC.

DESIGN

Retrospective case series.

PARTICIPANTS

Patients presenting with cavitary retinoblastoma who were treated with IAC.

METHODS

Retrospective case series of all patients presenting with cavitary retinoblastoma between August 2014 and January 2019 who were treated with primary IAC.

MAIN OUTCOME MEASURES

Tumor regression, recurrence, resolution of vitreous and subretinal seeds, number of treatments required, globe salvage, metastasis, and death.

RESULTS

Eight cavitary retinoblastoma tumors in 6 eyes of 4 patients were treated with IAC. One hundred percent of the cavitary tumors regressed (8/8 tumors, in 6/6 eyes), and 100% of vitreous and subretinal seeds regressed, with 100% globe salvage. None of the tumors recurred, no patients developed metastases, and no patients died. Eyes were treated with a median of 4.5 cycles of IAC (range, 1-7), with fewer IAC treatments used in the later patients (1-3 treatments per eye for the most recent 3 eyes, compared with 6-7 treatments per eye for the earliest 3 eyes). Mean reduction in thickness was 73.4% (range, 59.7%-84.6%). Mean reduction in basal diameter was 45.5% (range, 24.8%-56.0%).

CONCLUSIONS

Treatment with IAC results in regression of cavitary retinoblastoma, often with greater reduction in tumor size than has been reported previously with intravenous chemotherapy (IVC). Using up-front triple therapy (e.g., melphalan 0.4 mg/kg, carboplatin 50 mg, and topotecan 2 mg) and noting certain subtle signs of early regression can help to minimize unnecessary additional cycles of treatment.