Pomalidomide, Cyclophosphamide, and Dexamethasone (POMCIDEX) in Relapsed/Refractory Multiple Myeloma

This multicenter, retrospective, real-world study (GEM-POMCIDEX) was initiated to evaluate the effectiveness of the guidelines established by the Spanish Myeloma Group (PETHEMA) to treat appropriate patients with relapsed/refractory multiple myeloma (RRMM) with pomalidomide, cyclophosphamide, and dexamethasone (POMCIDEX). The goal of the guidelines was to provide uniform management of relapsed patients and to improve the overall response rate (ORR), quality (depth and duration) of response, and progression-free survival (PFS).

The study included 100 patients who were treated with the following POMCIDEX regimen: pomalidomide 4 mg on days 1-21, cyclophosphamide 50 mg/day, dexamethasone 40 mg weekly (20 mg if aged ≥75 years). The median age of the study cohort was 69 years (range, 39-86 years). In terms of prior treatments, 64.5% of patients were refractory to proteasome inhibitors, 89% were refractory to lenalidomide, and 60% were double-refractory; 57.6% were refractory to lenalidomide as the last line of therapy. In total, 82% of patients were refractory to the last line of therapy.

For patients taking POMCIDEX according to the PETHEMA guidelines, ORR was 39%. Stringent complete response was achieved by 6% of patients, complete response (CR) was achieved by 1% of patients, 12% achieved very good partial response, and 20% achieved partial response (PR). The clinical benefit rate (>stable response) was 93%. When analyzed by subgroup according to prior medications, the ORR was consistently maintained with the exception of those receiving lenalidomide as their last line of therapy. These patients showed a lower ORR (29.82%). In addition, those with extramedullary disease (EMD) also achieved a lower ORR (12.5%).

The median PFS was 7.6 months (95% confidence interval [CI], 5.78-10.12) for the study population. For those who achieved at least a PR, PFS was significantly longer (10.4 months; 95% CI, 7.4-19.1) versus those who did not achieve PR (5.4 months; 95% CI, 3.9-8.1) (hazard ratio [HR], 2.0; 95% CI, 1.3-3.1; P = .001). For subgroups divided by prior medication, median PFS was sustained; however, those with EMD had a significantly shorter median PFS of 5.4 months (95% CI, 2.8-7.3) versus 8.8 months (95% CI, 6.4-12.4) for those who did not have EMD (HR, 1.7; 95% CI, 1.05-2.75; P = .030).

Median overall survival (12.6 months; 95% CI, 9.3-18.2) shared a similar pattern, with those who achieved at least PR having significantly longer overall survival than those who did not, that is, 18.2 months (95% CI, 11.2-41.3) versus 9.85 months (95% CI, 7.1-14.0) (HR, 0.52; 95% CI, 0.3-0.8). As with PFS, the median overall survival was sustained across all subgroups studied, except for the subgroup of patients with EMD.

Hematologic adverse events (AEs) occurred in 43% of patients, and nonhematologic AEs occurred in 79% of patients. Disease progression was the primary reason for discontinuation; only 2 patients discontinued due to AEs. Of the patients enrolled in this study, 76% have died (57% due to disease progression, 6% due to AEs).

The authors concluded that POMCIDEX is an effective, manageable, and cost-effective treatment that offers the attractive option of an all-oral administration route drug combination for patients with RRMM.

Reference

  • Abstract and Poster EP982. EHA 2020. June 12, 2020. Pomalidomide, cyclophosphamide and dexamethasone (POMCIDEX) for the treatment or relapse and refractory multiple myeloma (RRMM): real-world analysis of the PETHEMA-GEM experience.

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