SKYSCRAPER-03: A Phase III, Open-Label, Randomized Study of Atezolizumab Plus Tiragolumab Compared With Durvalumab in Patients With Locally Advanced, Unresectable, Stage III NSCLC Who Have Not Progressed After Platinum-Based Concurrent Chemoradiation

Purpose/Objective(s)Until recently, the standard of care for patients (pts) with locally advanced, unresectable, stage III non-small cell lung cancer (NSCLC) has been platinum-based concurrent chemoradiation (cCRT); however, the 5-year OS rates are poor (13–36%; Goldstraw et al. J Thorac Oncol 2015). Durvalumab (anti-PD-L1) monotherapy was recently approved for pts without progressive disease (PD) after cCRT. However, long-term OS data are not yet available and further evaluation of novel cancer immunotherapy combinations should be explored. Targeted inhibition of a novel checkpoint TIGIT/PVR, by the anti-TIGIT antibody tiragolumab, may amplify the anti-cancer activity of anti-PD-L1/PD-1 antibodies. In the phase II CITYSCAPE study (NCT03563716), tiragolumab plus atezolizumab (anti-PD-L1) was well tolerated and improved ORR compared with atezolizumab alone (31.3 vs 16.2%) in 1L pts with PD-L1+ (TPS ≥1%) metastatic NSCLC; with greater benefit in the PD-L1-high (TPS ≥50%) subset. We hypothesize that tiragolumab plus atezolizumab may provide greater clinical benefit vs single-agent anti-PD-L1 as maintenance therapy in pts with unresectable, stage III NSCLC who have not progressed after platinum-based cCRT. SKYSCRAPER-03 (NCT04513925) will determine if tiragolumab plus atezolizumab provides superior clinical benefit to durvalumab in this setting. Current data suggests that cCRT upregulates PD-L1 expression, potentially enabling PD-L1 low or negative tumors to derive benefit, so outcomes will be evaluated in all-comer (ITT) and PD-L1+ sub-populations.Materials/MethodsEligible pts (≥18 years) must have unresectable, stage III NSCLC without PD after ≥2 cycles of platinum-based cCRT per NCCN/ESMO guidelines, and without an EGFR mutation or ALK rearrangement; known PD-L1 status; ECOG PS 0–1. Approximately 800 pts will be randomized 1:1 to receive tiragolumab 840mg IV plus atezolizumab 1680mg IV Q4W or durvalumab 10mg/kg IV Q2W / 1500mg IV Q4W. Treatment will continue for up to 13 cycles of 28 days, or until unacceptable toxicity or symptomatic deterioration due to PD; in pts with radiographic PD (per RECIST v1.1) treatment may continue if evidence of ongoing clinical benefit. Stratification factors include PD-L1 status, histology (squamous vs non-squamous), staging (IIIA vs IIIB or IIIC) and ECOG PS (0 vs 1). Primary endpoint is independent review facility-assessed PFS in the ITT and PD-L1+ (TC ≥1%) populations. Secondary endpoints include investigator-assessed PFS, OS, ORR and DoR. Safety and biomarker analyses will be performed. Recruitment is ongoing.ResultsforthcomingConclusionforthcoming Until recently, the standard of care for patients (pts) with locally advanced, unresectable, stage III non-small cell lung cancer (NSCLC) has been platinum-based concurrent chemoradiation (cCRT); however, the 5-year OS rates are poor (13–36%; Goldstraw et al. J Thorac Oncol 2015). Durvalumab (anti-PD-L1) monotherapy was recently approved for pts without progressive disease (PD) after cCRT. However, long-term OS data are not yet available and further evaluation of novel cancer immunotherapy combinations should be explored. Targeted inhibition of a novel checkpoint TIGIT/PVR, by the anti-TIGIT antibody tiragolumab, may amplify the anti-cancer activity of anti-PD-L1/PD-1 antibodies. In the phase II CITYSCAPE study (NCT03563716), tiragolumab plus atezolizumab (anti-PD-L1) was well tolerated and improved ORR compared with atezolizumab alone (31.3 vs 16.2%) in 1L pts with PD-L1+ (TPS ≥1%) metastatic NSCLC; with greater benefit in the PD-L1-high (TPS ≥50%) subset. We hypothesize that tiragolumab plus atezolizumab may provide greater clinical benefit vs single-agent anti-PD-L1 as maintenance therapy in pts with unresectable, stage III NSCLC who have not progressed after platinum-based cCRT. SKYSCRAPER-03 (NCT04513925) will determine if tiragolumab plus atezolizumab provides superior clinical benefit to durvalumab in this setting. Current data suggests that cCRT upregulates PD-L1 expression, potentially enabling PD-L1 low or negative tumors to derive benefit, so outcomes will be evaluated in all-comer (ITT) and PD-L1+ sub-populations. Eligible pts (≥18 years) must have unresectable, stage III NSCLC without PD after ≥2 cycles of platinum-based cCRT per NCCN/ESMO guidelines, and without an EGFR mutation or ALK rearrangement; known PD-L1 status; ECOG PS 0–1. Approximately 800 pts will be randomized 1:1 to receive tiragolumab 840mg IV plus atezolizumab 1680mg IV Q4W or durvalumab 10mg/kg IV Q2W / 1500mg IV Q4W. Treatment will continue for up to 13 cycles of 28 days, or until unacceptable toxicity or symptomatic deterioration due to PD; in pts with radiographic PD (per RECIST v1.1) treatment may continue if evidence of ongoing clinical benefit. Stratification factors include PD-L1 status, histology (squamous vs non-squamous), staging (IIIA vs IIIB or IIIC) and ECOG PS (0 vs 1). Primary endpoint is independent review facility-assessed PFS in the ITT and PD-L1+ (TC ≥1%) populations. Secondary endpoints include investigator-assessed PFS, OS, ORR and DoR. Safety and biomarker analyses will be performed. Recruitment is ongoing. forthcoming forthcoming