Education and decision-support only — not a medical device or personalised advice. Always discuss your specific situation with your specialist team.
What is uveal melanoma — and why is it different?
Uveal melanoma is a type of melanoma that starts in the eye — specifically in the uvea, which includes the iris, ciliary body, and choroid. It is the most common primary eye cancer in adults, but it is rare overall (affecting roughly 5–7 people per million per year in the UK and USA).
Crucially, uveal melanoma is biologically distinct from cutaneous (skin) melanoma:
- It rarely carries the BRAF V600 mutation that drives most skin melanomas — so BRAF + MEK inhibitors (used widely in skin melanoma) do not work against uveal melanoma.
- It is also largely resistant to standard checkpoint inhibitors (anti-PD-1, anti-CTLA-4) that transformed outcomes in skin melanoma — response rates to nivolumab or pembrolizumab in uveal melanoma are typically under 5%.
- Approximately 50% of uveal melanoma patients develop metastatic disease, most commonly spread to the liver. Once metastatic, median survival has historically been measured in months (often 12–15 months).
Until 2022, no therapy had ever demonstrated an overall survival benefit in a randomised trial for metastatic uveal melanoma. That changed with tebentafusp.
What is tebentafusp (Kimmtrak)?
Tebentafusp is a first-in-class bispecific T-cell receptor (TCR) therapy — sometimes called an ImmTAC (immune-mobilising monoclonal TCR against cancer):
- One "arm" of the molecule binds to a fragment of the gp100 protein (a melanocyte antigen) that is presented on the surface of uveal melanoma cells via the HLA-A*02:01 immune molecule.
- The other "arm" binds to CD3 on T-cells, physically bringing T-cells into proximity with uveal melanoma cells and triggering them to kill the tumour.
This mechanism bypasses the normal limitations of PD-1/CTLA-4 checkpoint blockade, which is why tebentafusp works in uveal melanoma even though standard checkpoint inhibitors do not.
Important eligibility note: Tebentafusp only works in patients who are HLA-A*02:01 positive — this HLA type is present in approximately 45–50% of people of European ancestry, with varying rates in other populations. A blood test can determine your HLA type.
What the IMCgp100-202 Phase 3 trial showed
The pivotal evidence comes from IMCgp100-202, a randomised Phase 3 trial that compared:
- Tebentafusp (weekly IV infusion) vs
- Investigator's choice (pembrolizumab, ipilimumab, or dacarbazine)
in 378 patients with previously untreated metastatic uveal melanoma who were HLA-A*02:01 positive [1].
Primary results (median follow-up 14.1 months):
| Outcome | Tebentafusp | Investigator's choice |
|---|---|---|
| 1-year overall survival (OS) | 73% | 59% |
| Median OS | 21.7 months | 16.0 months |
| Hazard ratio for death | 0.51 (95% CI 0.37–0.71) |
In other words: patients receiving tebentafusp were nearly half as likely to die at any given time point compared with the control arm. This was the first time any treatment had improved overall survival in a Phase 3 trial for metastatic uveal melanoma.
Three-year update (NEJM 2023): The survival benefit was sustained at three-year follow-up. Approximately 27% of tebentafusp patients were alive at three years, compared with 18% in the control arm [2].
How does tebentafusp compare to other options?
Before tebentafusp, the options for metastatic uveal melanoma were limited and offered modest benefit. A published comparative analysis (propensity-score weighting) against nivolumab + ipilimumab showed tebentafusp maintained its overall survival advantage [3]. Direct head-to-head data against all second-line options are still limited.
Who is tebentafusp for?
Tebentafusp is specifically indicated for:
- Adults with previously untreated metastatic uveal melanoma
- Patients who are HLA-A*02:01 positive (essential requirement — the drug does not work in HLA-A*02:01-negative patients)
Availability:
- FDA approved January 2022 (first-line metastatic uveal melanoma, HLA-A*02:01+)
- UK (NICE): assess the NICE appraisal status with your oncologist or check the NICE website — coverage decisions evolve
- Available through specialist centres; your melanoma MDT can advise on referral
What side effects should I expect?
Tebentafusp has a distinct side-effect profile from checkpoint inhibitors:
- Cytokine release syndrome (CRS): fever, chills, low blood pressure — very common, especially after the first few infusions. Typically manageable in a monitored setting; serious CRS is uncommon.
- Skin reactions: rash, pruritus — very common (related to the drug targeting melanocytes in the skin)
- Liver enzyme elevation — common; usually temporary
- Fatigue — common
Most patients are monitored closely for at least 16 hours after the first three doses. Side effects generally decrease in intensity after the first few weeks.
What to ask your oncologist
- Have I been tested for HLA-A*02:01? (If not, ask for this test)
- Is tebentafusp approved or available in the UK through NICE or an expanded access programme?
- Are there active clinical trials for uveal melanoma that I should consider?
- Are there specialists at a regional melanoma centre who have experience with tebentafusp?
See our Clinical Trial Finder and the Melanoma Focus UK patient resources for further support.
References
[1] Nathan P, Hassel JC, Rutkowski P, et al. Overall Survival Benefit with Tebentafusp in Metastatic Uveal Melanoma. N Engl J Med. 2021;385(13):1196–1206. PMID 34551229
[2] Three-Year Overall Survival with Tebentafusp in Metastatic Uveal Melanoma. N Engl J Med. 2023. PMID 37870955
[3] Overall survival from tebentafusp versus nivolumab plus ipilimumab in first-line metastatic uveal melanoma. Ann Oncol. 2024. PMID 38048850
Education and decision-support only — not a medical device. Does not diagnose, screen, predict, or provide personalised medical advice. Discuss all treatment decisions with your specialist team.