SKYSCRAPER-08: A phase III, randomized, double-blind, placebo-controlled study of first-line (1L) tiragolumab (tira) + atezolizumab (atezo) and chemotherapy (CT) in patients (pts) with esophageal squamous cell carcinoma (ESCC).
Chih‐Hung Hsu, Zhihao Lü, Shegan Gao, Junye Wang, Jong‐Mu Sun, Tianshu Liu, Qingxia Fan, Jun Cai, Fei-Jiao Ge, Sijing Li, Li Zhang, Edward Cha, Lin Shen
Abstract
245 Background: Inhibition of TIGIT, a novel checkpoint inhibitor, may further amplify immune responses by complementing the PD-L1/PD-1 pathway. Anti-tumor activity has been demonstrated with cancer immunotherapy in ESCC. SKYSCRAPER-08 (NCT04540211) is evaluating the efficacy and safety of tira (anti-TIGIT) + atezo (anti-PD-L1) in combination with CT compared with placebo + CT as 1L treatment (tx) in an Asian population with unresectable locally advanced (LA), unresectable recurrent, or metastatic (R/M) ESCC. Methods: Eligible pts (confirmed LA or R/M ESCC; ECOG PS 0–1; no prior systemic tx) were randomized 1:1 to receive tira 600mg + atezo 1200mg + CT (paclitaxel 175mg/m2 + cisplatin 60–80mg/m2, local standard of care) or placebo + CT on Day 1 of each 21-day cycle (cycles 1–6); followed by tira + atezo or placebo maintenance until loss of clinical benefit/unacceptable toxicity. Primary endpoints: independent review facility (IRF)-assessed progression-free survival (PFS) and overall survival (OS). Secondary endpoints: investigator (INV)-assessed PFS, objective response rate (ORR), duration of response (DoR), and safety. Results: Overall, 461 pts were randomized (tira + atezo + CT, n= 229; placebo + CT, n=232). Pt characteristics were generally balanced between arms. As of 15 June 2022 (minimum survival follow-up 6.5 months [mo]; PFS primary analysis), median IRF-assessed PFS was 6.2 mo for tira + atezo + CT vs 5.4 mo for placebo + CT (HR 0.56; 95% CI: 0.45, 0.70; P<0.0001). As of 13 Feb 2023 (minimum survival follow-up 14.5 mo; OS final analysis), median OS was 15.7 mo for tira + atezo + CT vs 11.1 mo for placebo + CT (HR: 0.70; 95% CI: 0.55, 0.88; P= 0.0024). INV-assessed PFS, IRF-assessed ORR and DoR are presented in Table. Treatment-related adverse events (TRAEs) occurred in 98.2% of pts (both arms); Grade 3/4 TRAEs in 59.6% (tira + atezo + CT) and 56.4% (placebo + CT) of pts; Grade 5 TRAEs in 2.6% (tira + atezo + CT) and 0.9% (placebo + CT) of pts. Conclusions: The study met both primary endpoints of IRF-assessed PFS and OS, demonstrating statistically significant and clinically meaningful improvements in PFS and OS for tira + atezo + CT over placebo + CT. Generally consistent benefit was observed across subgroups, including PD-L1 status. The safety profile was consistent with the known risks of the individual tx. Clinical trial information: NCT04540211 . [Table: see text]