Progression-Free and Overall Survival After KRd Consolidation in FDG PET/CT Positive Patients After ASCT: A Phase II...

In multiple myeloma, ¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) positivity after first-line autologous stem cell transplantation (ASCT) is associated with reduced progression-free survival (PFS) and overall survival (OS). Intensified treatment may abrogate the adverse effects of a positive PET after ASCT, but this treatment strategy has not been evaluated in prospective clinical trials.

In this phase II clinical study, patients who were in at least very good partial response (VGPR) after ASCT and had a positive PET received four cycles of KRd treatment. These patients were compared with patients in at least VGPR after ASCT that were PET negative and received standard post-ASCT treatment. Bone-marrow based minimal residual disease (MRD) assessment at a sensitivity of 10^-5 was performed before and after treatment in the PET positive patients.

After a median follow-up of 53 months, PFS was similar between PET positive patients who received KRd and PET negative patients who received standard of care (median 65.3 months vs. median 51.3 months, P = .610). Median OS was not reached in either group. MRD status after KRd treatment was significantly associated with PFS and OS, and patients who were both MRD and PET positive after KRd treatment had poor prognosis.

Long-term outcomes were similar between PET positive patients who received KRd consolidation therapy and PET negative patients who received standard post-ASCT therapy. Newer treatment strategies are needed for patients who are both PET/CT and MRD positive after intensified consolidation therapy.