SKYSCRAPER-02: Primary Results of A Phase III, Randomized, Double-Blind, Placebo-Controlled Study of Atezolizumab (Atezo) Plus Carboplatin Plus Etoposide (CE) with or Without Tiragolumab (tira) in Patients (pts) With Untreated Extensive-Stage Small Cell Lung Cancer (ES-SCLC).