Haploidentical Allogeneic Cell Transplantation in Relapsed/Refractory Multiple Myeloma

Area of Science:

• Hematology
• Oncology
• Transplantation Immunology

Background:

• Emerging therapies have improved multiple myeloma (MM) treatment, but long-term control in relapsed/refractory (r/r) MM remains challenging.
• The role of natural killer cell alloreactivity in haploidentical allogeneic HCT with PTCy for GvHD prophylaxis is established for other hematologic neoplasms but controversial in MM.

Purpose of the Study:

• To evaluate the efficacy and safety of haploidentical allogeneic HCT with PTCy in a small cohort of heavily pretreated patients with r/r MM.

Main Methods:

• Retrospective analysis of seven consecutive patients with r/r MM undergoing haploidentical allogeneic HCT with PTCy.
• Patients received proteasome inhibitors, anti-CD38 antibody, immunomodulatory drugs, and at least one autologous HCT prior to HCT.
• Conditioning regimens included chemotherapy and radioimmunotherapy; GvHD prophylaxis involved PTCy with tacrolimus and mycophenolate mofetil.

Main Results:

• All patients achieved stable engraftment with complete donor chimerism.
• Initial responses included 4 complete remissions (CR) and 3 very good partial remissions (VGPR).
• Among survivors, median time to relapse was 26.5 months; 4 of 5 maintained CR at last follow-up. Acute GvHD grades III-IV occurred in 2 patients, and chronic GvHD in 4, with no GvHD-related deaths.

Conclusions:

• Haploidentical allogeneic HCT with individualized conditioning regimens can achieve disease control in heavily pretreated r/r MM patients.
• The approach demonstrated manageable GvHD, suggesting potential for this strategy in select MM populations.