Safety and efficacy of posterior sub-Tenon's carboplatin injection versus intravitreal melphalan therapy in the management of retinoblastoma with secondary vitreous seeds

Evidence in Focus: The Sparse Landscape of Randomized Trials on Retinoblastoma Treatment

Background

Retinoblastoma, although rare, is one of the most common intraocular malignancies worldwide. Its prognosis has improved significantly in the past few decades, thanks to modern treatments, like systemic, intra-arterial, and intravitreal chemotherapy. However, regarding survival, there are significant differences between high- and low-income countries, eye salvage is still a challenge worldwide, and treatment-related toxicity needs to be carefully and sufficiently managed.

Summary

To appraise the strength of supporting evidence, we performed a systematic review of randomized controlled trials investigating any therapeutic protocol for retinoblastoma. Four trials with 174 participants (188 eyes) were eligible, all pertaining to different intravenous chemotherapy regimens. Vincristine, etoposide, and carboplatin (VEC) appear superior to a 5-drug combination for stage III retinoblastoma. Moreover, etoposide and carboplatin as neoadjuvant chemotherapy followed by thermochemotherapy seem to offer better local control than vincristine and carboplatin. However, increasing carboplatin dose in the VEC protocol failed to improve treatment efficacy.

Key Messages

Retinoblastoma is a success story of modern medicine. However, only intravenous chemotherapy has been studied through randomized trials, while evidence for the most novel retinoblastoma treatments has mainly stemmed from observational studies. International collaborations for multicenter randomized trials could overcome difficulties and increase certainty and precision in the field.

Addition of intravitreal carboplatin with melphalan for management of vitreous seeding in retinoblastoma

PURPOSE

To evaluate the efficacy and toxicity of intravitreal carboplatin plus melphalan for the treatment of vitreous seeds in eyes with retinoblastoma (RB).

METHODS

This retrospective series at a tertiary referral center included 22 consecutive RB patients who had received intravitreal carboplatin (16 μg per 0.05 ml) combined with melphalan (30 μg in 0.03 ml) [IVi (Ca-Me)] for treatment of vitreous seeds. Tumor control and drug toxicities were recorded.

RESULTS

There were 22 eyes of 22 patients, divided into primary group (n = 13) without history of previous intravitreal chemotherapy (IViC) and refractory group (n = 9) with history of previous IViC using melphalan and/or topotecan. The demographics and clinical findings of the primary and refractory groups did not differ significantly. The 6-month follow-up revealed complete vitreous seed control (77% vs. 89%, p = 0.47). Vitreous seed recurrence was detected in 1 eye of each group at 6 months. During the next 18-month follow-up period, no recurrence of seed was observed. The response to IVi (Ca-Me) was not significantly influenced by previous IViC (p = 0.70), primary systemic or intra-arterial chemotherapy (p = 0.45), or the type of regression (p = 0.35). The most common tumor treatment complications were retinal detachment (RD) (n = 2), early hypotony (n = 2) and late hypotony (n = 4, unrelated), cataract (n = 2), and severe pigment dispersion (n = 1). Enucleation was performed in 8 eyes, for total RD (n = 1), phthisis bulbi (n = 5), and extensive solid tumor recurrence (n = 2). There was no case of orbital invasion, systemic metastasis, or death.

CONCLUSION

Based on this interventional case series for primary and refractory vitreous RB seeds, carboplatin plus melphalan therapy may be effective with few toxic side effects.

Hydrogel implants for transscleral diffusion delivery of topotecan: In vivo proof of concept in a rabbit eye model

Treatment of retinoblastoma (Rb) has greatly improved in recent years in terms of survival and eye salvage rates, using mainly intra-arterial or intravitreal chemotherapy. However, the treatment of vitreous tumor seeding still represents a challenge and it is of great interest to develop new strategies to deliver pharmacologically sufficient drug amounts to the vitreous humor. In the present work, we present a lens-shaped bi-layered hydrogel implant for delivery of topotecan (TPT) via transscleral diffusion. The implant consists of an inner TPT-loaded poly(2-hydroxyethyl methacrylate) (pHEMA) layer adjacent to the sclera and an outer covering poly(2-ethoxyethyl methacrylate) (pEOEMA) layer impermeable to TPT. TPT-loaded pHEMA samples exhibit long-lasting in vitro cytotoxicity against the Rb cell line Y79. In an in vivo experiment, pHEMA/pEOEMA implants are successfully surgically administered to the posterior segment of rabbit eyes. The determination of TPT pharmacokinetics demonstrates the attainment of promising levels of TPT (10 ng/ml) in vitreous humor 8 h after implant placement. The results from the pilot experiment constitute the proof of principle for the use of the proposed implants as a drug delivery system for the local treatment of intraocular diseases.

A single-arm study of systemic and sub-Tenon chemotherapy for Groups C and D intraocular retinoblastoma: A Children's Oncology Group study (ARET 0231)

BACKGROUND

Eyes with Group D intraocular retinoblastoma have low salvage rates. A pilot study showed safety and efficacy of sub-Tenon's fascia carboplatin with systemic chemotherapy supporting further study.

METHODS

Children with newly diagnosed bilateral intraocular retinoblastoma with at least one remaining Group C or D eye were treated with six courses of carboplatin/etoposide/vincristine (CEV) with sub-Tenon's fascia carboplatin for Group C/D eyes during courses 2-4. Local ophthalmic therapy started at course 3. The primary study objective was to determine the 1-year failure rate of Group D eyes.

RESULTS

The study closed prematurely due to poor accrual and 22 of 30 patients were evaluable for failure rate, contributing 25 Group D and four Group C eyes. Among the 25 Group D eyes, there were 13 failures within the first year of study enrollment including eight needing external beam radiotherapy (EBR) and five needing enucleation, resulting in 1-year failure rate of 52%. The failure rate was significantly lower than the historical rate of 70% (P = .039). The 1-year eye preservation rate for Group D eyes was 80% (20/25). One-year failure rate for Group C eyes was 25% (1/4); 1-year preservation rate was 100% without need for EBR. Systemic toxicity included Grade 3 hearing loss in two subjects, infections, neutropenia, and thrombocytopenia. Ocular toxicities included periorbital fat atrophy (13/29 = 45% eyes), optic nerve atrophy (1/29 = 3% eyes), and restrictive fibrosis (1/29 = 3% eyes).

CONCLUSIONS

Sub-Tenon's fascia carboplatin plus CEV was partially effective in Group D intraocular retinoblastoma but had unacceptable ocular toxicities.

The Inhibitory Effect of Carboplatin Injection on Human Neuroblastoma SK-N-SH

The purpose of our study was to investigate the inhibitory effect of carboplatin injection on human neuroblastoma human neuroblastoma cell (SK-N-SH) cells and to clarify its action mechanism. In this study, human neuroblastoma SK-N-SH cells were divided into two groups. The treatment group was intervened by carboplatin injection (25 μM), while the control group was intervened by drug solvent. After treating separately for 24 and 72 h, the cells were collected, and western blot (WB) and real-time PCR were used to detect the expression of the proliferation marker protein (Ki67); cells grown on cover slips were prepared and immunocytochemistry (ICC) and hematoxylin-eosin (HE) staining were adopted to observe the protein expression of Ki67 and the morphological changes of the cells; clone formation assay was used to detect the clonality of each cell group. The cytotoxicity of carboplatin on SK-N-SH cell was checked by AlamarBlue viability test. Both WB and PCR results showed that after cells were injected with carboplatin for 24 and 72 h, the expression levels of both Ki67 gene and protein were decreased, and they had a significant difference from those of the control group. Carboplatin injection inhibited the expression of Ki67, and the inhibitory effect was particularly significant as the action time prolonged. ICC results showed that the protein expression of Ki67 in the treatment group was lower than that in the control group, and there was a significant difference in expression between them. As shown by HE results, the number of cell necrosis and apoptosis in the treatment group was significantly higher than that in the control group, while the results of clone formation assay showed that in the treatment group, after being injected with carboplatin, the proliferation ability of cells was inhibited, so the number of cells was significantly reduced compared with that of the control group. Carboplatin at the tested concentration displayed no cytotoxicity on SK-N-SH cell. The conclusions are that carboplatin injection can inhibit human neuroblastoma SK-N-SH cells, and the longer it acts on SK-N-SH cells, the more obvious the inhibitory effect would be.