Tebentafusp
Kimmtrak; IMCgp100; tebentafusp-tebn
Tebentafusp is a bispecific fusion protein combining an affinity-enhanced TCR (recognising the gp100 peptide-HLA-A*02:01 complex on uveal melanoma cells) with an anti-CD3 single-chain variable fragment that engages and activates T cells. It is the first systemic therapy with a demonstrated overall-survival benefit in HLA-A*02:01+ metastatic uveal melanoma — the IMCgp100-202 phase 3 trial (Nathan, NEJM 2021) showed 1-year OS 73% vs 59% with investigator's choice (pembrolizumab / ipilimumab / dacarbazine), HR 0.51. NICE TA1027 (published 9 January 2025) recommends tebentafusp for HLA-A*02:01+ adults with unresectable / metastatic uveal melanoma. The principal toxicity is cytokine release syndrome in the first three doses, managed with step-up dosing and hospital monitoring.
Mechanism
- An affinity-enhanced T-cell receptor (TCR) recognising the gp100 melanoma-associated peptide (YLEPGPVTA) presented on HLA-A*02:01 of tumour cells.
- Linked to an anti-CD3 single-chain variable fragment that activates resting polyclonal T cells.
- Brings cytotoxic T cells into proximity with uveal-melanoma cells, redirecting them to lyse tumour irrespective of the patient's native TCR repertoire.
- Restricted to HLA-A*02:01-positive patients (~ 45% of UK Caucasian population).
Evidence
- IMCgp100-202 (phase 3) — Nathan et al., NEJM 2021. 378 HLA-A*02:01+ patients with previously untreated metastatic uveal melanoma; randomised tebentafusp vs investigator's choice (pembrolizumab, ipilimumab, dacarbazine).
- Overall survival HR 0.51 (95% CI 0.37–0.71); 1-year OS 73% vs 59%; 3-year OS 27% vs 18%.
- OS benefit despite low objective response rate (9% vs 5%) — disease-control and tumour-shrinkage independent of formal RECIST response.
- Median PFS 3.3 vs 2.9 months.
- IMCgp100-102 (phase 2) — confirmed activity in pre-treated patients.
- NICE TA1027 (published 9 January 2025) recommends tebentafusp for unresectable / metastatic uveal melanoma in HLA-A*02:01+ adults.
Dosing and administration
- Weekly IV infusion as a step-up regimen:
- Day 1 (week 1) — 20 µg.
- Day 8 (week 2) — 30 µg.
- Day 15 (week 3) onwards — 68 µg weekly.
- First three doses administered in a hospital setting with at least 16-hour observation post-dose for cytokine release syndrome.
- Subsequent doses may be given in outpatient infusion unit with 30-minute observation if tolerated.
- Hold or discontinue per CRS management algorithm.
Toxicities
- Cytokine release syndrome (CRS) — most common toxicity, ~ 90% of patients; peaks with first 3 doses then subsides. Fever, chills, hypotension, tachycardia. Grade ≥ 3 in 1–2%. Management — IV fluids, antipyretics, corticosteroids; tocilizumab for refractory.
- Cutaneous — pruritus, rash (often urticarial or maculopapular), vitiligo. Rash typically improves over time; topical / oral antihistamines, topical corticosteroids.
- Pyrexia — frequently associated with CRS but also as isolated event.
- Hepatic enzymes — transaminase elevation; monitor and dose-adjust.
- Hypotension during infusion — fluid responsive.
- Lymphopenia, anaemia.
- Severe CRS / hypotension / liver dysfunction may necessitate dose interruption or discontinuation.
Practical UK implementation
- HLA-A*02:01 typing required prior to treatment (NHS Genomic Medicine Service).
- Treatment in specialist ocular / cutaneous melanoma centres with experience in CRS management.
- Most patients continue treatment until disease progression or unacceptable toxicity.
- Imaging response often understates clinical benefit — treat through stable / minor progression where clinically appropriate.
- Combined approaches with locoregional liver therapy for hepatic metastases (~ 90% of UM metastatic disease) under specialist input.
References
- Nathan P et al. Overall survival benefit with tebentafusp in metastatic uveal melanoma. N Engl J Med; 2021;385:1196–1206.
- NICE TA1027 (published 9 January 2025) — Tebentafusp for treating advanced uveal melanoma.
- Carvajal RD et al. Clinical and molecular response to tebentafusp in previously treated patients with metastatic uveal melanoma (IMCgp100-102). Nat Med; 2022.
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