Efficacy and Safety of Parsaclisib in Patients with Relapsed or Refractory Mantle Cell Lymphoma Not Previously Treated with a BTK Inhibitor: Primary Analysis from a Phase 2 Study (CITADEL-205)

Background: Mantle cell lymphoma (MCL) is an aggressive type of non‐Hodgkin lymphoma (NHL) and accounts for 6% of all NHL cases in Western countries (Thandra KC. Med Sci. 2021;9:5). First-line treatment options are not curative and most patients (pts) experience relapse (Wu H. Front Oncol. 2020:10:588314; Kumar A. Blood Cancer J. 2019;9:50). Targeted therapies, including Bruton's tyrosine kinase (BTK) inhibitors, are used as second- and later-lines; however, treatment intolerance and failure are common with poor survival outcomes (Epperla N. Hematol Oncol. 2017;35:528-35; Jain P. Br J Haematol. 2018;182:404-11). Thus, novel therapies are needed for pts with relapsed or refractory (R/R) MCL. Parsaclisib is a potent, highly selective, next-generation inhibitor of phosphatidylinositol 3-kinase (PI3K) δ. Here, we report results of the primary analysis of the cohort of BTK inhibitor-naive pts with R/R MCL treated with parsaclisib monotherapy in the open-label, phase 2 study CITADEL-205 (NCT03235544, EudraCT 2017-003148-19).