Metastatic disease from uveal melanoma occurs in almost 50% of patients suffering from this ocular tumour, with median survival from development of symptoms being around 1 year. In contrast to cutaneous melanoma, kinase inhibitors and immune checkpoint inhibitors are usually ineffective in patients with metastatic uveal melanoma. Tebentafusp is a novel form of immunotherapy based on the immune-mobilising monoclonal T cell receptor against cancer (ImmTAC) platform, which comprises a soluble T cell receptor that is fused to an anti-CD3 single-chain variable fragment. The T cell receptor domain of tebentafusp targets cells present a human leukocyte antigen-A*02:01 complexed with a peptide derived from the melanoma-associated antigen gp100, which is expressed strongly by melanoma cells, weakly by normal melanocytes and minimally by other tissues. The anti-CD3 domain recruits CD3+ T cells (and, indirectly, other immune cells), redirecting these to the melanoma cells. The most common adverse events with tebentafusp are manageable and usually transient. Early survival data in patients with metastatic uveal melanoma are promising when considered alongside historical data. Based on these encouraging results, a randomised study comparing tebentafusp to investigator’s choice of therapy in metastatic uveal melanoma is ongoing.

Almost 50% of all patients with choroidal melanoma die of metastatic disease, despite successful eradication of the primary ocular tumor.¹ In 1978, Zimmerman et al² suggested that enucleation might accelerate death due to metastatic disease. This hypothesis encouraged the Collaborative Ocular Melanoma Study Group^3,4 to compare enucleation with (1) iodine plaque brachytherapy and (2) enucleation combined with neoadjuvant radiotherapy in a series of randomized studies. These studies concluded that the prevention of metastatic spread was achieved as effectively with enucleation as with both comparison treatments. In fact, these study findings were inconclusive because many patients already had metastatic spread by the time of diagnosis and treatment, as evidenced by the short survival times.⁵ Because prevention of what has already happened is impossible, such patients should have been excluded from the studies, which would have left insufficient numbers of patients to achieve adequate statistical power. Therefore, whether ocular treatment influences survival, and if so in whom, remains to be shown.

Proton beam radiotherapy of uveal melanoma can be administered as primary treatment, as salvage therapy for recurrent tumor, and as neoadjuvant therapy prior to surgical resection. The physical properties of proton beams make it possible to deliver high-doses of radiation to the tumor with relative sparing of adjacent tissues. This form of therapy is effective for a wider range of uveal melanoma than any other modality, providing exceptionally-high rates of local tumor control. This is particularly the case with diffuse iris melanomas, many of which are unresectable. The chances of survival, ocular conservation, visual preservation and avoidance of iatrogenic morbidity depend greatly on the tumor size, location and extent. When treating any side-effects and/or complications, it is helpful to consider whether these are the result of collateral damage or persistence of the irradiated tumor ('toxic tumor syndrome').

Purpose: To validate the Liverpool Uveal Melanoma Prognosticator Online (LUMPO) in a cohort of patients treated at the University of California-San Francisco (UCSF). Methods: A retrospective chart review was performed of 390 patients treated between 2002 and 2007 for choroidal melanoma at UCSF. Similar patients (n = 1175) treated at the Liverpool Ocular Oncology Centre (LOOC) were included in the study. The data were analyzed using the model previously developed for LUMPO, an online prognostication tool combining multiple prognostic factors. Main outcome measures included all-cause mortality and melanoma-specific mortality. Reliability of the survival estimates in each group of patients was indicated by the C-indices of discrimination and Hosmer-Lemeshow test. Results: Patients treated at UCSF tended to be younger with thicker tumors, and were more likely to receive proton beam radiotherapy as primary treatment compared to patients at LOOC. There were no significance differences with respect to ciliary body involvement, melanoma cytomorphology, and mitotic counts between the two groups. Death occurred in 140/390 (35%) patients from UCSF and 409/1175 (34%) patients from LOOC, with no difference in overall mortality by Kaplan-Meier analysis (log rank test, P = 0.503). For all-cause mortality and melanoma-specific mortality, the C-index of discrimination and Hosmer-Lemeshow test at 5 years after treatment indicated good discrimination performance of the model, with no statistically significant difference between observed and predicted survival. Conclusions: Despite differences between the two cohorts, external validation in patients treated at UCSF indicates that LUMPO estimated the all-cause and melanoma-specific mortality well.