Selinexor Efficacy and Safety Are Independent of Renal Function in Patients with Relapsed/Refractory Diffuse Large B-Cell Lymphoma (DLBCL): A Post-Hoc Analysis from the Pivotal Phase 2b Sadal Study

Introduction: Selinexor is a first-in-class Selective Inhibitor of Nuclear Export (SINE) that blocks XPO1, forcing the nuclear retention and re-activation of tumor suppressor proteins including p53, p73, FOXO, IkB and Rb. The phase 2b SADAL study included 134 patients with relapsed or refractory DLBCL with single agent oral selinexor twice weekly. The overall response rate (ORR) was 29.1%, median duration of response (DOR) was 9.3 months and the median overall survival (OS) was 9 months. Based on these data, selinexor was recently approved by the US FDA for the treatment of relapsed or refractory DLBCL, de novo or transformed from follicular lymphoma. Patients with DLBCL tend to have a number of comorbidities, including poor renal function, which can require a reduction in the dose of intensive chemotherapy as well as lenalidomide, leading to inferior outcomes. Selinexor is not metabolized nor cleared by the kidneys and has been demonstrated to be safe and active in patients with myeloma and renal dysfunction. We performed post-hoc analyses of the SADAL study to determine the efficacy and safety among patients stratified by renal function at baseline.

Methods: The SADAL study is multi-center, open-label Phase 2b study that enrolled patients with DLBCL previously treated with 2-5 lines of therapy. Patients may have progressed post-stem cell therapy (SCT) or were not candidates for SCT. In this study, 60 mg of selinexor was administered twice weekly until disease progression. The primary endpoint was ORR, and other endpoints included DOR, OS, and safety assessments. For the current analysis, outcomes were assessed according to baseline renal function as estimated by the Cockroft-Gault formula for creatinine clearance (CrCl). Groups included those with reduced (CrCl ≤60 mL/min) and normal (CrCl >60 mL/min) renal function.

Results: Of 134 patients, 37 (28%) had a reduced baseline CrCl (≤60 mL/min) while 97 (72%) had CrCl >60 mL/min. The median age of patients with reduced CrCl was 74 years with 70% ≥70 years, while the median for those with normal CrCl was 65 years, with 35% ≥70 years. De novo and transformed DLBCL showed similar renal function levels: 78% and 22% with reduced CrCl and 76% and 24% with normal CrCl. Of patients with reduced CrCl, the DLBCL subtype was 41% GCB and 57% non-GCB compared to 50% and 46% in patients with normal CrCl. The group of patients with reduced CrCl had baseline ECOG performance status of 2 in 16% vs 11% in those with normal CrCl. Treatment with selinexor demonstrated a similar ORR in patients with a baseline reduced CrCl (29.7%) versus normal CrCl (28.9%). A complete response (CR) was observed in 8 (21.6%) patients with reduced and 10 (10.3%) patients with normal CrCl. The median duration of response (DOR) in patients who had reduced CrCl was 23.0 months compared to 9.2 months in patients with normal CrCl. The median progression-free survival (PFS) was 3.5 months (95% CI 1.7, 24.8) and 2.3 months (95% CI 1.9, 3.7) and overall survival was 7.8 months and 9.1 months in patients with reduced CrCl and those with normal CrCl. The most common grade ≥3 treatment-related AEs for patients with reduced versus normal CrCl were thrombocytopenia (45.9% vs. 38.1%), nausea (5.4% vs. 6.2%), and fatigue (8.1% vs. 11.3%). There was no clinically significant increase in treatment-related serious adverse events (21.6% vs. 20.6%) and adverse events leading to discontinuation (10.8% vs. 7.2%) in patients with reduced or normal CrCl, respectively.

Conclusions: Selinexor showed similar anti-DLBCL activity and tolerability in patients with relapsed/refractory DLBCL with a reduced renal function (CrCl <60 mL/min) compared to those with normal (CrCl ≥60 mL/min) renal function. No dose adjustments are required in patients with renal dysfunction and DLBCL who are treated with selinexor.