Phase 3 IMCgp100-202 Trial of Tebentafusp Shows Promise for Metastatic Uveal Melanoma

The phase 3 IMCgp100-202 clinical trial of tebentafusp (IMCgp100) versus investigator’s choice in metastatic uveal melanoma has met its pre-defined boundaries for statistical significance of the primary end point of overall survival (OS) in its first pre-planned interim analysis conducted by an independent data monitoring committee, according to Immunocore, the developer of the agent.

The phase 3 IMCgp100-202 clinical trial was designed to evaluate the OS of tebentafusp compared to investigator’s choice of either dacarbazine, ipilimumab (Yervoy), or pembrolizumab (Keytruda) in patients with previously untreated metastatic uveal melanoma. In total, 378 patients were randomized 2:1 to receive either tebentafusp or investigator’s choice.

In the intent-to-treat population, the OS hazard ratio (HR) was found to have favored tebentafusp (HR, 0.51; 95% CI, 0.36-0.71; P < .0001) over investigator’s choice (pembrolizumab, 82%; ipilimumab, 12%; dacarbazine, 6%). Though not yet mature, the Kaplan-Meier estimates also suggested a 1-year OS rate of approximately 73% versus 58%, respectively.

These efficacy data confirm the promising OS observed in the phase 2 study IMCgp100-102 in previously treated metastatic uveal melanoma. In addition, uveal melanoma has one of the lowest tumor mutational burdens (TMB) and these results indicate that the ImmTAC platform should be evaluated in tumors with low or high TMB status.

“A positive survival benefit for tebentafusp represents a major step towards bringing a potential new treatment for cancer patients with a high unmet need,” Bahija Jallal, chief executive officer of Immunocore, said in a press release. “If approved, tebentafusp would be the first new therapy to improve overall survival in 40 years and to be specifically indicated for metastatic uveal melanoma, a disease with poor survival and where new therapies are urgently needed. We look forward to sharing these data with the medical community and Health Authorities in the near future.”

Tebentafusp is a novel bispecific protein engineered to specifically target gp100, a lineage antigen expressed in melanocytes and melanoma, and is the first molecule developed using technology designed to redirect and activate T cells to recognize and kill tumor cells. The agent has already been granted fast track designation by the FDA and was also previously granted orphan drug designation for uveal melanoma by the FDA and Promising Innovative Medicine designation under the UK Early Access to Medicines Scheme.

Final results from IMCgp100-202 are expected to be presented at an upcoming scientific conference and to be submitted for publication in a peer-reviewed journal. Findings from this study will also be presented next month at the ESMO Immuno-Oncology Virtual Congress 2020.

Reference:

Immunocore’s tebentafusp demonstrates superior overall survival compared to investigator’s choice in a Phase 3 clinical trial of patients with previously untreated metastatic uveal melanoma [news release]. Oxfordshire, England & Conshohocken, Pennsylvania & Rockville, Maryland. Published November 23, 2020. Accessed November 23, 2020. https://www.immunocore.com/news/immunocores-tebentafusp-demonstrates-superior-overall-survival-compared-investigators-choice-phase-3-clinical-trial-patients-pre