P-145: Early M protein immune reconstitution is a good prognostic marker for patients with high-risk cytogenetic multiple myeloma after autologous hematopoietic stem cell transplantation

Introduction: The presence of transient monoclonal immunoglobulins (i.e. M-protein immune reconstitution) in serum immunofixation electrophoresis after autologous hematopoietic stem cell transplantation in patients with multiple myeloma has been reported, and patients with high-risk cytogenetics tend to have poor prognosis; the purpose of this paper is to investigate the impact of post-transplant M-protein immune reconstitution on the prognosis of patients with high-risk cytogenetic multiple myeloma

Methods: To retrospectively analyze the clinical data of 290 newly diagnosed multiple myeloma patients from August 1, 2008 to July 31, 2021 at the First Affiliated Hospital of Sun Yat-sen University, all of whom underwent sequential autologous hematopoietic stem cell transplantation after induction therapy, and to analyze and compare the clinical characteristics and prognostic survival of patients with and without M-protein immune reconstitution

Results: M protein immune reconstitution was observed in 25.9% (75/290 patients), the most common type of immunoglobulin was IgG-λ. The median time to obtain reconstruction was 3 months (1-38 months) and the median duration was 4 months (1-39 months) after transplantation, and there were no statistical differences in disease stage, tumor load and cytogenetics between the immune reconstituted and unreconstructed groups. The CR rate and MRD negativity were higher in the M protein immune reconstitution group (P=0.019, 85.3% vs 69.3%, P=0.014, 81.9% vs 66.5%), and although there were no statistical differences in PFS and OS between the M protein immune reconstitution group and the group without immune reconstruction, the overall median survival time was longer in the M protein immune reconstruction group (P=0.137, 80m vs 72m; P=0.800, 49m vs 33m).Among patients in the cytogenetic high-risk group, access to M protein immune reconstitution predicted better PFS and OS (P=0.011, 80m vs 31m; P=0.079, 54m vs 16m).Also in R-ISS stage III patients, PFS and OS were better in patients who obtained M protein immune reconstitution than in those who did not (P=0.008, 80m vs 20m; P=0.044, 52m vs 26m).

Conclusions: Better prognosis in immune reconstructed patients may be associated with the acquisition of a deeper response, but in high-risk patients, early acquisition of immune reconstitution may suggest a better prognosis.