Abstract CT002: Phase 3 randomized trial comparing tebentafusp with investigator's choice in first line metastatic uveal melanoma
Authors: Piperno-Neumann Sophie , Hassel Jessica C. , Rutkowski Piotr , Baurain Jean-Francois , Butler Marcus O. , Schlaak Max , Sullivan Ryan J. , Ochsenreither Sebastian , Dummer Reinhard , Kirkwood John M. , Joshua Anthony M. , Sacco Joseph J. , Shoushtari Alexander N. , Orloff Marlana , Carvajal Richard D. , Hamid Omid , Abdullah Shaad E. , Holland Chris , Goodall Howard , Nathan Paul 
Published: July 2021

Background: Metastatic uveal melanoma (mUM) has a poor prognosis with a 1-yr OS rate of 52%. No systemic treatment has proven an OS benefit in randomized trials. Tebentafusp (tebe), a bispecific consisting of an affinity-enhanced T cell receptor (TCR) fused to an anti-CD3 effector that can redirect T cells to target gp100+ cells, has shown promising activity in previously treated mUM pts. Here, we report the primary analysis of overall survival (OS) in the intention-to-treat population (ITT) of a Ph3 trial of tebe vs. investigator's choice (IC) as first line (1L) therapy in pts with mUM [NCT03070392].

Materials and Methods: In this randomized, open-label, Ph3 trial, 1L HLA-A*02:01+ pts with mUM were randomized 2:1 to receive tebe or IC of pembrolizumab, ipilimumab or dacarbazine, stratified by LDH. The primary endpoint was OS, defined as the time from randomization to death from any cause. Dual primary objectives were to evaluate 1) OS in the ITT population by comparing all tebe-randomized pts to all IC-randomized pts; and 2) OS in tebentafusp-treated patients with rash during week 1 versus all IC-treated patients. Secondary endpoints included safety and RECIST-defined overall response rate (ORR), progression free survival (PFS) and disease control rate (DCR). Here we present the OS in the ITT population. The study was unblinded by an independent data monitoring committee at the first pre-specified interim analysis. Investigator-reported radiographic-based endpoints were not mature at the first interim analysis. This analysis was conducted on the first interim analysis (data extracted Nov 2020).

Results: 378 pts were randomized to tebe (252) or IC, including pembrolizumab (103), ipilimumab (15) or dacarbazine (7). Tebe significantly prolonged OS compared to IC (HR 0.51; 95% CI 0.36-0.71; P&lt;0.0001) in the ITT population, with estimated 1-yr OS rate of 73.2% (95% CI 66.3-78.9) vs 57.5% (95% CI 47.0-66.6), respectively. The OS benefit of tebe was observed in pre-specified subgroups, including by stratification variable of LDH&gt;ULN and versus pembrolizumab IC. Most common TRAEs were skin-related (gp100+ melanocytes) or cytokine-mediated (T cell activation) and included pyrexia, pruritus, and rash. These AEs decreased in frequency and severity after the first 3-4 doses and were generally manageable with standard interventions. In the tebe arm, the rate of treatment discontinuation due to TRAEs was low (&lt;4%), and there were no treatment-related deaths.

Conclusions: In 1L treatment of mUM pts, tebe monotherapy significantly improved OS compared to IC; the first investigational therapy to improve OS in pts with mUM. Tebe had a predictable and manageable AE profile with a low rate of related discontinuation. Tebe is the first TCR therapeutic to demonstrate an OS benefit.

Citation Format: Sophie Piperno-Neumann, Jessica C. Hassel, Piotr Rutkowski, Jean-Francois Baurain, Marcus O. Butler, Max Schlaak, Ryan J. Sullivan, Sebastian Ochsenreither, Reinhard Dummer, John M. Kirkwood, Anthony M. Joshua, Joseph J. Sacco, Alexander N. Shoushtari, Marlana Orloff, Richard D. Carvajal, Omid Hamid, Shaad E. Abdullah, Chris Holland, Howard Goodall, Paul Nathan. Phase 3 randomized trial comparing tebentafusp with investigator's choice in first line metastatic uveal melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT002.