Magnetic Resonance Imaging of Bone Marrow and its Results as a Criterion for Administration of Maintenance Therapy After Auto-HSCT in Multiple Myeloma Patients

Aim. To evaluate the efficacy of maintenance therapy in multiple myeloma (MM) patients after autologous hematopoietic stem cell transplantation (auto-HSCT) based on the results of MRI of bone marrow. Materials & Methods. The study included 32 MM patients aged 36 to 66 years (median 57 years) with complete remission after a single auto-HSCT. MRI of spine and pelvic bones was performed to identify the nature of bone marrow lesions and to determine the volume of tumor tissue on the day 100 after auto-HSCT. As maintenance therapy after auto-HSCT 14 patients received daily 15 mg lenalidomide in the period from day 1 to day 21 of the 28-day treatment course within 1 year. Monitoring of 18 patients was conducted without maintenance therapy. Statistical analysis included the assessment of progression-free survival (PFS) and relapse risk relationship to clinical and laboratory parameters. Results. Twenty patients had a positive MRI (tumor volume > 1 cm3). Zero variation of MR signal in bone marrow and detection of a < 1 cm3 tumor were regarded as a negative MRI, which was the case in 12 patients. After reaching the negative MRI the best rates of 2-year PFS were registered: 100 % with maintenance therapy and 84 % without maintenance therapy. In patients with tumor load on MR scans the 2-year PFS significantly (p = 0.03) varied and accounted for 80 % in patients who received maintenance therapy vs. 33 % in patients without maintenance therapy. Administration of maintenance therapy after detecting residual tumor on MR scans on day 100 after auto-HSCT has a positive effect on PFS rates. Multivariate analysis confirmed the residual tumor on MR scans of bone marrow to be the most important parameter PFS depends on. Conclusion. A negative MRI after auto-HSCT is a favourable prognostic factor determining a long-lasting (> 2 years) MM free period, despite the lack of maintenance therapy