SKYSCRAPER-02: Primary results of a phase III, randomized, double-blind, placebo-controlled study of atezolizumab (atezo) + carboplatin + etoposide (CE) with or without tiragolumab (tira) in patients (pts) with untreated extensive-stage small cell lung cancer (ES-SCLC).

LBA8507 Background: Atezo, in combination with CE, was the first cancer immunotherapy approved for 1L treatment of ES-SCLC. However, most pts eventually experience disease progression. TIGIT is a novel inhibitory immune checkpoint present on activated T cells and NK cells. Tira (anti-TIGIT) may synergise with other immunotherapies, such as PD-L1/PD-1 inhibitors, and further amplify the immune response to improve clinical outcomes. SKYSCRAPER-02 (NCT04256421) evaluates whether the antitumor effect and survival benefits of the combination of atezo + CE could be enhanced by adding tira in pts with ES-SCLC. Methods: Eligible pts with untreated ES-SCLC (asymptomatic treated or untreated brain metastases [BM] permitted) were randomized 1:1 to receive induction tira 600 mg IV or placebo (pbo) combined with atezo 1200 mg IV + CE for 4 x 21-day cycles followed by maintenance tira or placebo combined with atezo every 3 weeks until disease progression or loss of clinical benefit. Stratification factors include ECOG PS (0 vs 1); presence/history of BM (yes vs no); LDH (≤upper limit of normal [ULN] vs >ULN). Co-primary endpoints were investigator-assessed PFS and OS in all randomized pts without the history/presence of BM at baseline (primary analysis set [PAS]). Additional endpoints include PFS and OS in all randomized pts regardless of BM status (full analysis set [FAS]), objective response rate, duration of response, and safety. Results: A total of 490 patients were randomized (tira + atezo + CE, n=243; pbo + atezo + CE, n=247). As of 6 Feb 2022, median duration of follow-up was 13.9 months (mo); data represent final analysis for PFS and interim analysis for OS. In the PAS, no additional benefit was seen for tira + atezo + CE in PFS or OS compared with pbo + atezo + CE (Table). PFS and OS in the FAS were consistent with those observed in the PAS (Table). Grade 3/4 TRAEs occurred in 52.3% (tira + atezo + CE) and 55.7% (pbo + atezo + CE) and Grade 5 TRAEs occurred in 0.4% (tira + atezo + CE) and 2.0% (pbo + atezo + CE). TRAEs leading to any treatment discontinuation occurred in 5.0% and 5.3% with tira + atezo + CE and pbo + atezo + CE, respectively. Conclusions: The addition of tira to atezo + CE did not provide benefit over atezo + CE in pts with untreated ES-SCLC with or without BM. The combination was well tolerated, and no new safety signals were identified. The study will continue to planned final OS analysis. Clinical trial information: NCT04256421. [Table: see text]