# Bispecific T-Cell Engagers, Cell Therapies, and Other Non-Checkpoint Immunotherapies for Metastatic Uveal Melanoma: A Narrative Review

## TL;DR

This review summarizes recent non-checkpoint immunotherapy approaches for metastatic uveal melanoma, including bispecific T-cell engagers and adoptive-cell therapies, highlighting their efficacy and safety.

## Contribution

The paper provides a narrative synthesis of clinical evidence on emerging immunotherapies for metastatic uveal melanoma, focusing on efficacy and safety profiles.

## Key findings

- Tebentafusp improved median overall survival in HLA-A*02:01-positive patients with metastatic uveal melanoma.
- Tumor-infiltrating lymphocyte therapy showed durable remissions in some patients but had significant toxicity.
- Oncolytic viruses demonstrated limited radiographic responses but induced tumor-specific T-cell expansion.

## Abstract

Metastatic uveal melanoma (MUM) remains largely refractory to immune-checkpoint inhibition, so recent research has turned to bispecific T-cell engagers (BTCEs), adoptive-cell therapies (ACTs), and oncolytic viruses (OVs). To summarize the available clinical evidence, we performed a structured literature search across PubMed, Scopus, and Europe PMC for primary studies published between 1 January 2010 and 31 May 2025 that enrolled at least three adults with MUM, treated with one of these modalities, and that reported efficacy or grade-3+ safety outcomes; two reviewers independently performed screening, data extraction, and risk-of-bias assessment, and because of notable heterogeneity, we synthesized the findings narratively. Twenty-two studies met the criteria—thirteen phase I–III trials, eight observational cohorts, and one case series—covering fifteen BTCE cohorts, four ACT cohorts, and three OV cohorts. Tebentafusp, the dominant BTCE evaluated in roughly 1150 HLA-A*02:01-positive patients, extended median overall survival from 16.0 to 21.7 months (hazard ratio 0.51, with three-year follow-up HR 0.68) in its pivotal phase-III trial despite objective response rates of only 5–12%, with early skin rash and week-12 circulating-tumor-DNA clearance emerging as consistent markers of benefit. Tumor-infiltrating lymphocyte therapy, administered to about thirty patients, produced objective responses in 11–35% and occasional durable complete remissions, although median progression-free survival remained 2–6 months and severe cytopenias were universal. Three early-phase OV studies, totaling twenty-nine patients, yielded no radiographic responses but showed tumor-specific T-cell expansion and transient disease stabilization. Safety profiles reflected the mechanism of action: tebentafusp most often caused rash, pyrexia, and usually manageable cytokine-release syndrome with grade-3+ events in 40–70% yet discontinuation in roughly 2%; TIL therapy toxicity was driven by lymphodepleting chemotherapy and high-dose interleukin-2 with one treatment-related death; and OVs were generally well tolerated with no more than 20% grade-3 events.