OBJECTIVES : The Functional Assessment of Cancer Therapy - Multiple Myeloma (FACT-MM) was developed as a disease-specific, patient-reported outcome measure for the assessment of health-related quality of life (HRQoL) in patients with MM, as part of the FACT measurement system. The FACT-MM combines the General version of the FACT (FACT-G) with a MM-specific subscale (14 items). 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.

METHODS : STORM was single-arm, phase 2, open-label trial of oral selinexor in patients with penta-exposed, triple-class refractory MM, where the FACT-MM was collected at baseline and on Day 1 of each 4-week cycle. Patients were treated twice weekly, with dose modifications as needed, and continued treatment until disease progression. These data were used to explore two approaches for evaluating MCID: 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 selinexor patient level data. For each approach, an MCID decrease was considered to represent HRQoL decline at that cycle. The number and proportion of patients who declined based on the MCID was tabulated for each follow-up cycle.

RESULTS : Eighty patients were included. MCID thresholds were 16.4 for the first approach and 13.5 for the second. Most patients (range: 54% to 75% for the first approach; range 54% to 73% for the second) did not experience HRQoL decline during the first six cycles of selinexor.

CONCLUSIONS : Selinexor administration in RRMM did not lead to a decline in HRQoL, and exploratory MCIDs based on either method yielded consistent results, increasing the reliability of these methods to represent an MCID.