Adverse Events, Treatment Burden, and Outcomes of Intravenous versus Intra-arterial Chemotherapy for Retinoblastoma

Emerging New Therapeutics for Retinoblastoma

Background: Over the last few decades, chemotherapy has become the main treatment of retinoblastoma, delivered through various routes: intravenous, intra-arterial, and intravitreal. Despite its efficacy, chemotherapy-related toxicity (ocular and systemic) and recurrences due to resistant tumor clones are common, highlighting the need for novel therapeutic agents. Summary: Recent advances in our understanding of the molecular drivers of Rb1 tumorigenesis and mechanisms of tumor resistance have afforded opportunities to explore novel targets such as the MDMX-p53 pathway (nutlin-3), histone deacetylase inhibitors, spleen tyrosine kinase inhibitors, and genetic and immune modulatory drugs. In this review, we discuss the limitations of current therapeutic strategies, candidate cellular pathways, current evidence for newer targeted drugs, and offer a look toward the future. Key Messages: Advances in the understanding of the molecular drivers of the RB pathway have provided opportunities to explore novel drugs with targeted effects, improved bioavailability, and reduced chemotoxicity.

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.

Recent advancements in the management of retinoblastoma and uveal melanoma

Retinoblastoma in children and uveal melanoma in adults can pose a serious threat to both vision and life. For many decades, enucleation was often the only option to treat these intraocular malignancies. For retinoblastoma, intra-arterial chemotherapy is often utilized as the primary treatment at advanced academic centers and has dramatically improved local tumor control and eye salvage rates. For uveal melanoma, both plaque brachytherapy and proton beam irradiation have served as widely utilized therapies with a local failure rate of approximately 1–10%, depending on the series. Major recent advancements have allowed for a better understanding of the genomics of uveal melanoma and the impact of certain mutations on metastatic susceptibility. Gene expression profile stratifies uveal melanomas into two classes: low-risk (class 1) and high-risk (class 2). A loss-of-function mutation of BAP1 is associated with a class 2 gene expression profile and therefore confers worse prognosis due to elevated risk of metastasis. On the other hand, gain-of-function mutations of EIF1AX and SF3B1 correspond to a gene expression profile of class 1A and class 1B and confer a better prognosis. Preferentially expressed antigen in melanoma (PRAME) is an antigen that increases metastatic susceptibility when expressed in uveal melanoma cells. In addition to plaque brachytherapy and proton beam irradiation, both of which have demonstrated superb clinical outcomes, scientists are actively investigating newer therapeutic modalities as either primary therapy or adjuvant treatment, including a novel nanoparticle therapy and immunotherapy.

Effect of Intravenous Chemotherapy Regimen on Globe Salvage Success Rates for Retinoblastoma Based on Disease Class-A Meta-Analysis

Simple Summary

Intravenous chemoreduction (IVCRD) has been the standard of care for treatment of retinoblastoma (RB). Since survival rates exceed 95–98%, the goals of treatment have now shifted to emphasize eye salvage and vision preservation in addition to patient survival. Consequently, there has been a shift towards combining standard IVCRD with intravitreal chemotherapy or altogether replacing IVCRD with intra-arterial chemotherapy. As more data from intravitreal chemotherapy and intra-arterial chemotherapy are being published, there are claims of improved globe salvage rates resulting in more widespread use of these newer treatment modalities. However, there are no published randomized controlled trials comparing these to IVCRD head-to-head. To evaluate the relative efficacy of these new therapies, it is critical to determine the true success rates of IVCRD regimens alone. Therefore, it is both timely and essential to determine the baseline IVCRD success rates so that an evidence-based assessment of new and emerging therapies can be determined.

Abstract

To evaluate the relative efficacy of novel retinoblastoma treatments, eye classification-specific success rates for current standard-of-care intravenous chemotherapy regimens must be known. This meta-analysis included studies if: (1) patients received intravenous chemotherapy for retinoblastoma, (2) globe salvage data was reported, (3) only intravenous chemoreduction (with/without local consolidation) was used. The outcome measure was globe salvage success without need for salvage radiotherapy, subdivided by disease classification and chemotherapy regimen. Data from 27 studies (1483 eyes) were pooled. By Reese–Ellsworth classification, globe salvage rates were 85% (95%CI:73–92%) for Group I, 78% (95%CI:70–85%) for Group II, 68% (95%CI:56–78%) for Group III, 47% (95%CI:34–60%) for Group IV, and 35% (95%CI:26–45%) for Group V (Va: 35% [95%CI:21–54%]; Vb: 42% [95%CI:29–56%]; those without sub-classification: 31% [95%CI:19–47%]). By International Classification, globe salvage rates were 93% (95%CI:80–97%) for Group A, 83% (95%CI:73–89%) for Group B, 73% (95%CI:54–86%) for Group C, 40% (95%CI:31–51%) for Group D, and 19% (95%CI:5–50%) for Group E. Standard carboplatin-etoposide-vincristine out-performed two-drug regimens (odds ratio (OR) = 1.9 (95%CI:1.3–3.0) for Groups I-IV and OR = 2.1 (95%CI:1.3–3.4) for Group V; p = 0.002 for each). For eyes with diffuse vitreous seeds (Vb), an enhanced regimen out-performed standard chemotherapy (OR = 2.4 [95%CI:1.3–4.7]; p = 0.004). In conclusion, two-drug regimens were less effective for all eyes, whereas enhanced regimens were more effective for eyes with vitreous seeds. Novel therapies can now be compared to these baseline globe salvage rates.

Incidence and predictors of ophthalmic artery occlusion in intra-arterial chemotherapy for retinoblastoma

BACKGROUND

Retinoblastoma is the most common primary intraocular malignancy in children.

OBJECTIVE

To determine the incidence of ophthalmic artery (OA) occlusion in patients treated with selective ophthalmic artery catheterization (OAC) for chemotherapy infusion for retinoblastoma. Also, to evaluate technical, anatomical, tumorous, and patient-related factors that are predictors of OA occlusion.

METHODS

A retrospective chart review was performed for patients diagnosed with intraocular retinoblastoma and managed with intra-arterial chemotherapy (IAC).

RESULTS

The total study cohort included 208 retinoblastoma tumors of 208 eyes in 197 consecutive patients who underwent 688 attempted IAC infusions overall with a total of 624 successful OAC infusions. The total incidence of ophthalmic artery thrombosis was 11.1% (23/208). The numbers of successful OAC procedures before diagnosing OA occlusion were one OAC in six cases (27.3%), two in seven cases (31.8%), three in four cases (18.2%), four in one case (4.5%), five in two cases (9.1%), and six in one case (4.5%).

CONCLUSIONS

Local factors relating to the chemotherapy and selective microcatheterization of the OA are essential factors in the development of OA thrombosis, as seen by the association of OA thrombosis with the frequency of IAC.