**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Landsberg, Adina1, Burande, Aksha1, Lee, Holly1, McCulloch, Sylvia1, Tay, Jason1,2, Duggan, Peter1,2 and Jimenez-Zepeda,Victor1,2
1Tom Baker Cancer Center/University of Calgary
2Arnie Charbonneau Cancer Research Institute

**Main Body of the Abstract**
Background: Recently, based on a prospective screening of 41,882 individuals and after 3.5 years of follow up, the IstopMM group reported new reference intervals for serum free light chains (sFLC) particularly for patients with preserved renal function. In addition, new sFLC reference values were defined based on age (<70 or >70). Objectives: We aimed to describe the frequency of LC-MGUS based on the revised definition, as well as to assess clinical outcomes for patients deemed LC-MGUS with prior reference values. Methods: Retrospective chart reviews were performed in all cases seen at our clinic and demographic variables were recorded. Results A total of 418 patients with MGUS were evaluated in the study period. From those, 63 (15%) cases were deemed to have LC-MGUS. On these cases, 29 (46%) had an eGFR>60 mL/min/1.73m2, 16 (25%) (45-59 mL/min/1.73m2), 7 (11%) (30-44 mL/min/1.73m2) and 10 (15%) (<30 mL/min/1.73m2). After the new revised criteria was applied, LC-MGUS was described in only 20 cases (4.8%), representing a relative decrease of 69% of cases previously considered LC-MGUS. After a median follow up of 70 months, 18 patients in the LC-MGUS as per new criteria and 60 as per the old criteria are alive. No patients with LC-MGUS defined as per old and new criteria have progressed to MM or AL amyloidosis. Conclusion, Implementation of the new sFLC criteria defined as per the IstopMM group decreased the rate of false positive diagnosis of LC-MGUS, particularly for cases with preserved renal function (eGFR>60 mL/min/1.73m2).



**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Landsberg, Adina_1_, Burande, Aksha_1_, Lee, Holly_1_, McCulloch, Sylvia_1_, Tay, Jason_1,2_, Duggan, Peter_1,2_ and Jimenez-Zepeda,Victor1,2
**1**Tom Baker Cancer Center/University of Calgary
2Arnie Charbonneau Cancer Research Institute

**Main Body of the Abstract**
**Background**: Recently, based on a prospective screening of 41,882 individuals and after 3.5 years of follow up, the IstopMM group reported new reference intervals for serum free light chains (sFLC) particularly for patients with preserved renal function. In addition, new sFLC reference values were defined based on age (<70 or >70). **Objectives**: We aimed to describe the frequency of LC-MGUS based on the revised definition, as well as to assess clinical outcomes for patients deemed LC-MGUS with prior reference values. **Methods**: Retrospective chart reviews were performed in all cases seen at our clinic and demographic variables were recorded. **Results** A total of 418 patients with MGUS were evaluated in the study period. From those, 63 (15%) cases were deemed to have LC-MGUS. On these cases, 29 (46%) had an eGFR>60 mL/min/1.73m2, 16 (25%) (45-59 mL/min/1.73m2), 7 (11%) (30-44 mL/min/1.73m2) and 10 (15%) (<30 mL/min/1.73m2). After the new revised criteria was applied, LC-MGUS was described in only 20 cases (4.8%), representing a relative decrease of 69% of cases previously considered LC-MGUS. After a median follow up of 70 months, 18 patients in the LC-MGUS as per new criteria and 60 as per the old criteria are alive. No patients with LC-MGUS defined as per old and new criteria have progressed to MM or AL amyloidosis. **Conclusion,** Implementation of the new sFLC criteria defined as per the IstopMM group decreased the rate of false positive diagnosis of LC-MGUS, particularly for cases with preserved renal function (eGFR>60 mL/min/1.73m2).



Light-Chain MGUS defined as per the Revised definition of the ISTOPMM Study: Experience from the University of Calgary MGUS Clinic OB10 (#313)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.