Quality-of-life (QOL) analyses in patients with multiple myeloma: Results from the selinexor (KPT-330) treatment of refractory myeloma (STORM) phase IIb study.

Abstract

e20522 Background: Selinexor, a novel oral selective inhibitor of nuclear export, was recently approved for use in relapsed/refractory multiple myeloma (MM). The efficacy and safety of selinexor and dexamethasone was evaluated in a phase 2b, single-arm, open-label, multicenter trial in patients with penta-exposed, triple-class refractory MM. Patient-reported outcomes were measured using the Functional Assessment of Cancer Therapy - Multiple Myeloma (FACT-MM) assessment. While minimal clinically important differences (MCID) have been established for other FACT scales, there is no known, validated definition of MCID for the FACT-MM. This study reports results of QoL analyses in patients with MM enrolled in the STORM phase 2b trial and examines two approaches to calculate MCID for the FACT-MM. Methods: FACT-MM data were collected at baseline, on day 1 of each 4-week cycle, and at end of treatment (EOT) during the STORM phase 2b trial. Change from baseline was analyzed for the FACT-MM total score, FACT-trial outcome index (TOI), FACT-General (FACT-G), and the MM-specific domain. Two approaches for evaluating MCID were explored: the first based on patient-reported assessment of meaningful change, defined as 10% of the instrument range (Ringash 2007), and the second based on mean baseline differences between ECOG groups (0 vs 1 to 2) based on patient level data. Additional analyses were performed to identify trends among treatment responders and non-responders, including a difference-in-difference (DID) analysis to compare changes between baseline and EOT. Results: Eighty patients had sufficient data to be included in longitudinal QOL analyses. MCID analyses demonstrated that most patients did not experience decline during the first six cycles of treatment; this pattern was consistent with MCID defined either as 10% of the instrument range (range 54% to 75% of patients), or as an ECOG-based anchor (range: 54% to 73% of patients). The DID analysis found that the mean change in QoL of non-responders decreased significantly between baseline and EOT, while responders had no significant change. This difference between responders and non-responders was significant for the FACT-G. Conclusions: Most patients did not experience QoL decline during the early cycles of selinexor treatment during the STORM 2b trial. The MCID decline, evaluated by two approaches, was greater among treatment non-responders than responders. A DID approach demonstrated greater decline between baseline and EOT for non-responders. Clinical trial information: NCT02336815.