NS-62: The Importance of regular disease monitoring for patients with low or low intermediate risk Monoclonal Gammopathy of Undetermined Significance (MGUS)

Abstract

<h3>Background</h3> Monoclonal gammopathies encompass a number of disorders characterized by a clone of a normal protein. Although biologically heterogeneous, monoclonal gammopathy of undetermined significance (MGUS) represents the most common of these disorders with the production of a monoclonal protein (Mprotein). This abnormal clone of plasma or other lymphoid cells carries a variable risk of progression to a plasma cell disorders (PCDs) requiring treatment. Few studies report real-world incidence of progression from low risk MGUS to PCDs requiring therapy and with newer risk models. Purpose: To describe characteristics of patients who progress from MGUS to PCD requiring plasma cell directed therapy. <h3>Methods</h3> A list of all patients with MGUS seen at the Cleveland Clinic from 1/1998 to 6/2021 was obtained from an internal IRB approved data base. Demographic information, the date of antecedent MGUS diagnosis, and disease characteristics were confirmed. Patients were categorized as having low, low-intermediate, high intermediate, or high risk MGUS by assigning a point system as follows: Mprotein with IgA isotype (1point), Mprotein concentration of 1.5g/dL or more (1point), serum FLC ratio less than 0.1 or more than 10 (1point), and immunoparesis (≥1 uninvolved immunoglobulins below lower level of normal; 1-2 points).In the scoring system for light-chain MGUS, serum FLC ratio less than 0.1 or more than 10 (1 point) and immunoparesis (1, 2, or 3 points) were identified as risk factors. Patients were excluded if MGUS was diagnosed prior to 2004, missing sFLC, or MGUS <1 year. <h3>Results</h3> Included in this study were 3,188 charts of patients with confirmed MGUS. Of these, 209 were excluded as did not meet criteria for analysis. An additional 102 patient charts were excluded due to incomplete baseline disease evaluation, or a diagnosis of MGUS prior to 2004 (when light chain assay was commercially available). A total of 2,853 patients remained without evidence of disease progression according to 2014 IMWG diagnostic criteria. 23 patients (12M;11F) progressed from MGUS:14 progressed to MM, 6 progressed to amyloidosis, 2 progressed to WM and 1 progressed to MGRS. The median days from MGUS diagnosis to PCD diagnosis requiring therapy was 2,018 days (5.53y). Interestingly, 5 patients had 0 risk factors for progression but still progressed (3 MM, 2 Amyloidosis); 11 had 1 risk factor/low intermediate risk (7 MM,4 Amyloidosis); 6 had 2 risk factors (4 MM, 2 WM) while 1 had 3 risk factors (to MM). <h3>Conclusions</h3> Despite this small sample from a single institution, our findings are consistent with other studies in that the number of patients who progress from MGUS to other PCDs remains low. Routine monitoring can improve the time to diagnosis and minimize the risk of organ damage. Advanced practice providers and nurses are well-suited to monitor and mangage patients with MGUS.These findings support regular blood and urine testing for MGUS and ongoing risk assessment.