Impact of uveal melanoma thickness on post-plaque radiotherapy outcomes in the prophylactic anti-vascular endothelial growth factor era in 1131 patients

Efficacy of Prophylactic Anti-VEGF in Preventing Radiation Retinopathy: A Systematic Review and Meta-Analysis

Background

In patients predisposed to radiation retinopathy (RR), administration of therapy after apparent clinical signs and symptoms are considered too late, resulting in substantial vision loss and blindness. Early initiation of anti-vascular endothelial growth factor (anti-VEGF) might serve as a strategy to slow disease progression and prolong good eyesight.

Objective

To evaluate the efficacy of prophylactic anti-VEGF in preventing RR and preserving vision in patients at high risk of radiation-induced vision loss.

Methods

A systematic literature search was performed from inception to 4 June 2023 using Cochrane Library, EMBASE, PubMed (MEDLINE), and Scopus. Eligible studies were clinical trials and observational studies investigating the incidence of radiation maculopathy (RM), radiation optic neuropathy (RON), moderate vision loss (loss of more than or equal to 3 lines of baseline visual acuity [VA]) and final VA, whether good (20/40 or better) or poor (20/200 or worse), following prophylactic anti-VEGF. Three reviewers independently conducted article screening, data extraction and risk of bias assessment. Random effects models were used to determine the cumulative effects of each outcome.

Results

Four studies (one clinical trial and three observational studies), involving 2109 patients, were included in our analysis. Across all studies, there were significant reductions in the events of RM (pooled odds ratio [OR] 0.50; 95% CI, 0.34-0.74; p = 0.001), RON (pooled OR 0.62; 95% CI, 0.42-0.90; p = 0.012) and poor final VA (pooled OR 0.50; 95% CI, 0.37-0.68; p = 0.003). The association of moderate vision loss and good final VA with the use of prophylactic anti-VEGF between the groups was unclear owing to the high level of heterogeneity.

Conclusion

Prophylactic anti-VEGF therapy might delay RM and RON, preventing high-risk patients from developing poor VA by approximately 50%. However, this evidence should be interpreted with caution because of its low level of certainty. Future robust studies are warranted to confirm this finding.

Ocular Complications of Radiotherapy in Uveal Melanoma

Uveal melanoma is the most common primary malignant intraocular tumor in adults. Radiation therapy has replaced enucleation and is now the preferred treatment in most cases. Nonetheless, around 70% of patients develop radiation-related complications, some of which are vision-threatening. The objective of this review is to present the most important complications associated with radiotherapy in the treatment of uveal melanoma and their pathogenesis, incidence, risk factors, and available preventive and therapeutic measures. The most common complications are cataracts, with a reported incidence ranging from 4% to 69%, and radiation retinopathy, reported in 5-68% of cases. Radiation-related complications are responsible for approximately half of secondary enucleations, the leading cause being neovascular glaucoma. A poor visual outcome is mainly associated with the presence of radiation retinopathy and radiation optic neuropathy. Therapeutic options are available for the majority of complications with the notable exception of optic neuropathy. However, many studies report a final visual acuity of less than 20/200 in more than 60% of treated eyes. Reducing complication rates can be achieved by lowering the dose of radiation, with the use of eccentric, customized plaques and careful planning of the irradiation delivery in order to protect structures vital to vision and by associating radiation therapy with other methods with the aim of reducing tumor volume.

Hypoxia-dependent drivers of melanoma progression

Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.