Tebentafusp in HLA-A*0201 Positive Previously Untreated Metastatic Uveal Melanoma

Uveal Melanoma (UM) is a rare type of melanoma (3.1% of all melanoma incidence, approximately 4000 cases globally per year) with an incidence of 5.3-10.9 cases per million individuals. Despite its rare incidence rate, UM is the most frequent primary intraocular malignancy of the adult eye that affects the vascular layers of the eye (iris, ciliary body, and choroid). UM has a high incidence of metastases, predominantly to the liver, because of the lack of significant lymphatic traffic out of the eye and predominant hematogenous spread. Tebentafusp has been studied in four clinical studies including IMCgp100-01 (NCT01211262; ≥2L cutaneous and uveal melanoma), IMCgp100-102 (NCT02570308; ≥2L uveal melanoma), IMCgp100-201 (NCT02535078; PD-1 naïve and PD-1 R/R cutaneous melanoma), and IMCgp100-202 (NCT03070392; 1L uveal melanoma vs. physicians' choice chemotherapy). Based on early first-in-human (FIH) studies, tebentafusp 68 mcg was identified as the RP2D; with an intra- patient escalation regimen (20 mcg at C1D1 and 30 mcg at C1D8) and the dose escalated at C1D15. This dose was subsequently evaluated in a recently completed phase -II trial - IMC-p100-202 - that randomized 378 treatment-naïve, HLA-A\*0201 positive patients with advanced uveal melanoma on a 2-to-1 ratio to tebentafusp (n = 252) or investigator's choice (IC) of dacarbazine, ipilimumab, or pembrolizumab (n = 126). Based on the data from the IMCgp100-202 study, the current approved dose of tebentafusp is a fixed starting dose of 20mcg (C1D1), followed by 30 mcg (C1D8) and 68mcg at C1D15 and beyond. The primary outcome measure was updated to reference a tumor-informed ctDNA assay to align with the protocol language and description of the planned analysis.