Real-world treatment outcomes of carfilzomib plus dexamethasone in patients with relapsed and/or refractory multiple myeloma, focusing on the impact of trial-fitness: CAtholic REsearch network for Multiple Myeloma study (CAREMM-2203).

Introduction: Carfilzomib plus dexamethasone (Kd) is widely used in patients with relapsed and/or refractory multiple myeloma (RRMM). However, the treatment outcomes of Kd, especially in trial-unfit patients, have not been extensively studied in the real-world setting.

Methods: We analyzed the outcomes of 152 RRMM patients who received Kd at our hospitals from April 2018 to March 2022.

Results: At the commencement of Kd, patients received a median of two (range 1-7) lines of prior anti-myeloma therapy. According to the ENDEAVOR study criteria, 93 (61.2%) and 59 (38.8%) patients were classified as the trial-fit and the trial-unfit group, respectively. The overall response (OR) rate for the entire cohort was 71.1% (95% CI 63.2-78.1%). Progression-free survival (PFS) and overall survival (OS) were 5.6 months (95% CI 3.9-6.9 months) and 24.0 months (95% CI 13.4-38.0 months), respectively. There was no significant difference in the OR rate between the trial-fit and the trial-unfit groups (76.3% vs. 62.7%; P = 0.105). However, the median PFS (3.6 months vs. 7.3 months; P < 0.001) and OS (15.0 vs. 36.8 months; P = 0.009) were significantly shorter in the trial-unfit group. On multivariate analysis, trial-fitness (unfit vs. fit) remained a significant covariate influencing the TRM (HR: 4.84, 95% CI 1.66-14.06; P = 0.004) and PFS (HR: 1.82, 95% CI 1.27-2.62; P = 0.001).

Conclusion: Our data suggest that the treatment outcomes of Kd are acceptable in the real-world setting with significant differences between the trial-fit and the trial-unfit groups, although they are relatively inferior to those of a pivotal trial.