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Among patients with relapsed/refractory multiple myeloma (RRMM) with extramedullary disease (EMD), combining melflufen with dexamethasone appears to be safe and potentially efficacious, according to research presented at the virtual 2021 Lymphoma, Leukemia & Myeloma (LL&M) Congress.
Among patients with RRMM with EMD—which is linked with disease cells that proliferate independently of the bone marrow—prognosis is poor. No standard therapy for this patient population currently exists, suggesting a need for therapeutic advancement.
Melflufen, a peptide-drug conjugate targeting aminopeptidases, has previously shown efficacy among patients with RRMM in the HORIZON study (ClinicalTrials.gov Identifier: NCT02963493). In this sub-analysis, researchers evaluated data from HORIZON to determine the safety and efficacy of melflufen with dexamethasone among patients with RRMM with EMD.
Overall, data from 55 patients with RRMM with EMD were included in this analysis. Among these patients, 49% had soft-tissue plasmacytoma, while 51% had bone-related plasmacytoma; the median age was 64 years, 35% of patients had high-risk cytogenetics, and the median number of prior therapy lines was 5.
Among patients with RRMM with EMD, the overall response rate was 23.6% (95% CI, 13.2-37), the median duration of response was 5.5 months (95% CI, 1.8-not evaluable), the median progression-free survival was 2.9 months (95% CI, 2-3.8), and the median overall survival was 6.5 months (95% CI, 5.1-9.7).
Among 13 patients who reached a partial response or better and 28 patients who had stable disease or better, the median progression-free survival was 17.3 months and 5.3 months, respectively; the median overall survival was 18.5 months and 13.6 months, respectively.
Grade 3-4 treatment-emergent adverse events were noted in 78% of patients in the EMD subgroup, the most common of which were anemia (42%), thrombocytopenia (40%), neutropenia (38%), and pneumonia (9%). No treatment-related deaths were noted, however.
Richardson P, Mateos MV, Oriol A, et al. HORIZON (OP-106): melflufen plus dexamethasone in 55 patients with relapsed/refractory multiple myeloma with extramedullary disease—subgroup analysis. Poster presented at: 2021 Lymphoma, Leukemia & Myeloma Congress; October 19-23, 2021. Abstract OP-106.