March 2022: Tebentafusp-tebn (Kimmtrak, Immunocore Limited), a bispecific gp100 peptide-HLA-directed CD3 T cell engager, has been licenced by the Food and Drug Administration for HLA-A*02:01-positive adult patients with unresectable or metastatic uveal melanoma.
IMCgp100-202 (NCT03070392), a randomised, open-label, multicenter trial of 378 patients with metastatic uveal melanoma, was used to assess efficacy. HLA-A*02:01 genotype positivity was necessary, as determined by a central assay. Patients were excluded if they had had prior systemic or localised liver-directed treatment. Prior oligometastatic illness surgical resection was allowed. Patients with clinically severe heart disease or untreated symptomatic brain metastases were excluded from the study.
Tebentafusp-tebn (N=252) or investigator’s choice (N=126) of pembrolizumab, ipilimumab, or dacarbazine were given to patients in a 2:1 ratio. Tebentafusp-tebn was given as an intravenous infusion every week at a dose of 20 mcg on day 1, 30 mcg on day 8, 68 mcg on day 15, and every consecutive week until disease progression or intolerable toxicity. Overall survival was the primary efficacy outcome measure (OS). Investigator-assessed progression-free survival (PFS) using RECIST 1.1 was another efficacy endpoint. Patients treated with tebentafusp-tebn had a median OS of 21.7 months (95 percent CI: 18.6, 28.6), compared to 16 months (95 percent CI: 9.7, 18.4) in the investigator’s choice arm (HR=0.51, 95 percent CI: 0.37, 0.71, p0.0001). PFS for those taking tebentafusp-tebn was 3.3 months (95 percent CI: 3, 5) and 2.9 months (95 percent CI: 2.8, 3) in the investigator’s choice arm (HR=0.73, 95 percent CI: 0.58, 0.94, p=0.0139).
Cytokine release syndrome, rash, pyrexia, pruritus, exhaustion, nausea, chills, abdominal discomfort, edoema, hypotension, dry skin, headache, and vomiting were the most prevalent side effects (30%). Reduced lymphocyte count, increased creatinine, increased glucose, increased aspartate aminotransferase, increased alanine aminotransferase, decreased haemoglobin, and decreased phosphate were the most prevalent laboratory abnormalities (50 percent).
The recommended tebentafusp-tebn dose administered intravenously is:
- 20 mcg on day 1,
- 30 mcg on day 8,
- 68 mcg on day 15, and
- 68 mcg once weekly thereafter.
