Pomalidomide plus dexamethasone for patients with relapsed or refractory multiple myeloma: Final results of the non-interventional study POSEIDON and comparison with the pivotal phase 3 clinical trials

Abstract

Background: Prognosis of patients with multiple myeloma (MM) who have relapsed on or become refractory to immunomodulators and bortezomib is poor, and treatment options are limited. While pomalidomide plus low-dose dexamethasone (POM/DEX) has demonstrated efficacy in clinical trials, real-world evidence is scarce.

Patients and methods: POSEIDON was a prospective non-interventional study designed to evaluate effectiveness, safety and quality of life (QoL) of POM/DEX in patients with relapsed or refractory MM (R/RMM) pretreated with at least two prior therapy lines including both lenalidomide and bortezomib in real world in Germany. Patients received POM/DEX according to physicians' choice. Data were analyzed descriptively.

Results: Between 2014 and 2017, 151 patients were enrolled, 144 patients with a median of three prior therapy lines qualified for effectiveness analysis. Median age was 73.2 years. Median progression-free and overall survival were 6.3 months [95% confidence interval (CI) 5.2, 8.6] and 12.9 months [95% CI 10.6, 15.1]. Most frequent grade 3/4 adverse events were leukopenia (8.2%), pneumonia (7.5%) and anemia (5.5%). QoL was maintained after start of POM/DEX.

Conclusion: The results of POSEIDON support the effectiveness and safety of POM/DEX in R/RMM patients pretreated with lenalidomide and bortezomib and highlight the clinical value of the POM/DEX regimen in the real-world setting. Registered at clinicaltrials.gov (NCT02075996).

Keywords: Germany; dexamethasone; non-interventional study; pomalidomide; relapsed or refractory multiple myeloma; routine clinical practice.

FIGURE 1

Consort diagram. ^†Patients assigned to the corresponding cohort but without documented treatment start date, ^‡Includes only patients who received pomalidomide treatment, ^§The full analysis set (FAS) consists of all enrolled patients having received at least one dose of pomalidomide. Patients fulfilling at least one off‐label criteria (not having received at least two prior therapies, not having received both lenalidomide and bortezomib in previous therapy lines) were excluded from the FAS. Planned observation period (12 months) completed: for these patients no further pomalidomide treatment or incomplete information on pomalidomide treatment was documented in the follow up, and therefore, no reason for end of pomalidomide treatment in the follow up is available

FIGURE 2

Progression‐free survival (PFS) and overall survival (OS) of study patients. (A) PFS of the total patient population (FAS), (B) OS of the total patient population (FAS), (C) PFS stratified by cohorts. Cohort I represents patients with lenalidomide in last line prior to pomalidomide treatment and cohort II represents patients with no lenalidomide treatment in last line prior to pomalidomide treatment, (D) OS stratified by cohorts (i.e., cohort I and cohort II as described in C), (E) PFS stratified by refractory vs. relapsed MM. Refractory MM = PD on or within 60 days after last prior therapy; relapsed MM = PD >60 days after last prior therapy; (F) OS stratified by refractory vs. relapsed MM. For eight patients, an assignment to refractory or relapsed MM was not possible. FAS, full analysis set; MM, multiple myeloma; OS, overall survival; PD, progressive disease; PFS, progression‐free survival

FIGURE 3

Changes from baseline in patient‐reported quality of life (QoL) questionnaire scores. Boxplots of changes from baseline in EORTC QLQ‐C30 (global health status/QoL score only) and QLQ‐MY20 questionnaire scores. Higher scores in the global health status/QoL and functional scales (body image, future perspective) correspond to higher perceived QoL/healthy level of functioning, while higher scores in the symptom scales (disease symptoms, side effects) correspond to higher level of perceived symptoms severity based on the questionnaire results. Box: lower to upper quartile, horizontal line inside box: median, diamond inside box: mean, whisker: minimum/maximum value within lower quartile minus 1.5× IQR/upper quartile plus 1.5× IQR, respectively, circles: outliers outside of lower quartile minus 1.5× IQR/upper quartile plus 1.5× IQR, respectively (IQR, interquartile range)