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High-dose melphalan conditioning confers survival benefits in patients with extramedullary and non-extramedullary multiple myeloma.
High-dose melphalan appears to benefit patients with multiple myeloma (MM) regardless of extramedullary involvement, according to results of a single-site study presented at the 2024 ASCO Annual Meeting.
“According to our data, high dose melphalan conditioning prior to autologous stem cell transplant is equally as effective for patients with multiple myeloma with or without extramedullary involvement,” Darin Poei, MD, and coauthors wrote in the abstract of their study presented at the 2024 ASCO Annual Meeting.
Extramedullary multiple myeloma, the presence of multiple myeloma plasma cells that develop outside the bone marrow, is aggressive and is associated with poor prognosis. The current sequence in the standard of MM care involves induction, high-dose melphalan, autologous stem cell transplant (ASCT), and maintenance.
“High-dose melphalan 200 mg/m2 (Mel200) is the standard preparative regimen for MM,” Samer A. Strour, MBChB, MS, and coauthors, who were not involved in the study, explained in Haematologica. “Reduced-dose melphalan is frequently used as an alternative for older patients and those considered unfit for Mel200 because of frailty or medical comorbidities. Melphalan 100 mg/m2 (Mel100) was less effective compared with Mel200, albeit better tolerated. An intermediate dose of melphalan 140 mg/m2 (Mel140) has been widely used in older patients and those with significant comorbidities.” (Figure)
To contribute to the limited data in the literature on the outcomes of patients with extramedullary multiple myeloma who undergo ASCT, Dr. Poei and his colleagues retrospectively reviewed the records of 246 MM patients who underwent high-dose melphalan conditioning followed by ASCT between January 2017 and December 2022 at the USC Norris Comprehensive Cancer Center. At 100 days and 365 days post-transplant, the researchers compared the disease responses of the 70 extramedullary MM patients (67 had only paraskeletal involvement and 3 had soft tissue involvement) with the responses of the 176 non-extramedullary MM patients.
The 70 patients in the extramedullary MM group averaged 56.5 years of age at diagnosis; half were female; around 47% were Hispanic, 31% White, 11% Asian, and 6% African American. Also, in the extramedullary MM group, cytogenetic risk was standard at almost 49%, high at almost 26%, and unavailable at nearly 26%.
The 176 patients in the non-extramedullary MM group averaged 57.3 years at diagnosis; around 48% were female; around 44% were Hispanic, 24% were White, 15% were Asian, and 11% were African American. Also, in the extramedullary MM group, cytogenetic risk was standard in over 51%, high in almost 30%, and unavailable in over 19%.
- At 100 days post-ASCT and 365 days post-ASCT, no statistical significance was found between the extramedullary MM and non-extramedullary MM groups for progression-free survival.
- At 100 days post-ASCT, 69 (98.57%) patients in the extramedullary MM group and 175 (99.43%) patients in the non-extramedullary MM group were progression-free.
- At 365 days post-transplant, 61 (87.14%) patients in the EMM group and 155 in the non-EMM group (88.08%) were progression-free.
- At 100 and 365 days, there was no statistical significance between the groups in overall survival.
- At 100 days, no one in either group died.
- At 365 days, 69 (98.57%) of patients in the extramedullary MM group and 175 (99.43%) in the non-extramedullary MM group survived.
The authors plan to continue to follow these patients over time to determine whether the survival data for the extramedullary MM and non-extramedullary MM groups change with longer follow-up after ASCT. They plan to further evaluate “whether patient demographics, clinical characteristics, or pretransplant induction affect survival in multiple myeloma patients who receive ASCT,” they wrote in their poster.
