#1862 Post-kidney transplantation de novo monoclonal gammopathy of undetermined significance—impact on patients and graft long-term outcomes

Abstract

Abstract Background and Aims Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic premalignant plasma cell condition with a reported prevalence of 3 to 4% in population older than 50 years and progression to multiple myeloma in approximately 1% of the cases. The clinical significance of MGUS in patients diagnosed prior to kidney transplantation (KT) has previously been studied, however, the impact on survival and morbidity of newly diagnosed MGUS on the period after KT, remains unclear. The aim of this study was to compare the outcomes between patients with MGUS emerging after KT versus non-MGUS patients. Method This is a retrospective single-center cohort analysis of a population of 793 kidney transplant recipients between 1985 and 2022. Diagnosis of MGUS after KT was based on positive serum protein electrophoresis and confirmed by serum immunofixation. We performed a randomized selection of a matched control group, adjusted for age, gender, and KT duration. Both groups were compared for number of infections (bacterial and viral), acute rejections, neoplastic complications, and for overall patient and graft survival. Results This study included a total of 112 patients, with a mean age of 60 years (±11), of which 86 (77%) were older than 50 years. Median follow-up duration was 149 [IQR 89-207] months. We identified 56 patients (7%) with MGUS after KT. Only 1 (1.7%) patient progressed to multiple myeloma. Induction immunosuppression type was not associated with higher development of MGUS. We found no difference between the MGUS group and the control group in the incidence of infections, acute graft rejections, or solid and hematologic neoplasia (Table 1). There was also no difference between overall patient and graft survival. Conclusion MGUS is a premalignant disease frequently present in KT recipients, with a higher prevalence compared to the general population, although its development after KT does not appear to contribute to a worse prognosis or to a higher progression to multiple myeloma.