Intravitreal Chemotherapy Eligibility and Ocular Survival for Advanced Retinoblastoma

Abstract

Purpose : Vitreous seeding is a common cause of tumor relapse and poor ocular survival in patients with intraocular retinoblastoma. Intravitreal chemotherapy (IVC) is predominantly employed as salvage treatment for persistent or recurrent vitreous seeding. The purpose of this study was to determine the feasibility of primary IVC for the treatment of intraocular retinoblastoma with vitreous seeding.

Methods : We identified patients treated on a single institution phase II clinical trial for the treatment of retinoblastoma (NCT00186888). RET CAM images of each patient were retrospectively reviewed to identify eyes amenable to IVC at diagnosis and at subsequent examinations. Event-free survival (EFS) was defined as length of time to external-beam radiotherapy (EBRT) or enucleation. A log-rank test with p-values based on marginal computation was used for statistical analysis.

Results : 27 patients (54 eyes) were reviewed. Eyes were classified as Reese-Ellsworth group I-III (n=12) and IV-V (n=42) and International Classification of Retinoblastoma group A-B (n=17) and C-E (n=37). 27 eyes (50%) were deemed eligible for IVC at diagnosis. Of these 27 eyes, 6 (22%) had vitreous seeding. Of the 27 eyes deemed not eligible for IVC at diagnosis, 1 was excluded due to diffuse vitreous seeding, 1 due to phthisis bulbi, and 25 due to extensive subretinal detachment. Of these 27 eyes, 7 (26%) had vitreous seeding. After the completion of two courses of systemic vincristine and topotecan, 21 of these 27 eyes became eligible for IVC prior to the 3rd cycle of systemic chemotherapy.

Two additional eyes were deemed eligible prior to the 6th cycle of chemotherapy. 4 eyes (7%) did not reach eligibility due to either a persistent retinal detachment (n=1) or progressive disease (n=3). The EFS rate was 100% in eyes that were eligible for injection at time of diagnosis compared to 81% of those who reached eligibility at course 3 (p=0.019) and 0% of those who became eligible at course 6 or did not reach eligibility (p<0.0001).

Conclusions : Our retrospective study suggests that IVC can be incorporated early in the treatment of intraocular retinoblastoma to mitigate risk of recalcitrant vitreous disease. 89% were eligible for IVC prior to the 3rd course of chemotherapy. As expected, clearing of vitreous seeding correlated to improved EFS.

This is a 2021 ARVO Annual Meeting abstract.