Background: R-CHOP remains the standard of care for DLBCL. Although most patients (pts) can be cured, 35?40% will experience relapsed/refractory disease, leading to poor outcomes in the majority of pts. Covalent irreversible Bruton tyrosine kinase inhibitors (BTKi) have shown higher responses in pts with non-GCB DLBCL than with GCB DLBCL. In untreated non-GCB DLBCL pts, the phase 3 PHOENIX study (Younes et al. J Clin Oncol. 2019;37:1285-95) showed that addition of the BTKi ibrutinib to R-CHOP (R-CHOP-I) did not improve outcomes in the intent-to-treat population. However, pts age < 60y treated with R-CHOP-I had significantly improved progression-free survival (PFS) and overall survival (OS) compared with those receiving R-CHOP alone. Acalabrutinib (A) is a second-generation BTKi with enhanced kinase selectivity and potential for better efficacy and tolerability than first-generation BTKis. There is a strong rationale for combining A with R-CHOP in pts with untreated DLBCL, and safety of A + R-CHOP has been shown in a phase 1b/2 study (Davies et al. ASH 2020). The aim of this study is to determine if the addition of A to R-CHOP leads to improved PFS in pts age ≤65y with untreated non-GCB DLBCL. Methods: ESCALADE (ACE-LY-312; NCT04529772) is a phase 3, randomized, global, double-blind study of A vs placebo in combination with R-CHOP for treatment of newly diagnosed non-GCB DLBCL. The study is recruiting adults ≥18y and ≤65y with previously untreated DLBCL stage II?IV disease with a Revised International Prognostic Index (R-IPI) score of 2?5. Prior to randomization, all pts will receive an initial R-CHOP cycle (cycle 1) as standard-of-care treatment to prevent delays in therapy initiation. Based on central Gene Expression Profile (GEP) testing performed after enrollment, pts with non-GCB DLBCL (activated B-cell like or unclassified) will be randomized into 2 arms to receive A 100 mg twice daily plus R-CHOP or placebo plus R-CHOP from cycle 2 to cycle 6 followed by 2 additional cycles of rituximab + A or placebo (cycles 7 and 8). All pts will receive primary prophylaxis with granulocyte colony-stimulating factors accompanying all R-CHOP cycles. The study aims to randomize 600 pts (̃300 per arm). The primary objective is to evaluate whether the addition of A to R-CHOP will prolong PFS. Secondary endpoints include event-free survival, complete response rate, OS, pharmacokinetics, and safety. Key exclusion criteria are central nervous system involvement, primary mediastinal lymphoma, high-grade B-cell lymphoma, diagnosis or treatment of malignancy other than DLBCL, and history of indolent lymphoma. Approximately 250 sites globally will enroll pts. Enrollment began in Q3 of 2020. Clinical trial information: NCT04529772