**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.**
Giovanni Palladini, Amyloidosis Research and Treatment Center, Foundation "Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico San Matteo", Department of Molecular Medicine, University of Pavia, Italy

**Main Body of the Abstract**
Validated hematologic progression criteria in AL amyloidosis are lacking. Validation based on survival is difficult because rescue is started based on clinical judgment and relevant differences exist between referral centers. However, validated organ progression criteria are available that predict survival. Thus, we identified changes in differential free light chains (dFLC) associated with organ progression as candidate hematologic progression criteria.
The prospectively maintained ReAL registry (NCT04839003) was searched for patients treated from 2004 to 2021 who attained at least a very good partial response to first-line therapy and had a treatment-free interval >6 months from best response. Receiver operator characteristic (ROC) analyses were used to identify the dFLC cutoff (percent of value at diagnosis and absolute increase from nadir) best predicting organ progression (in addition to validated criteria we considered renal progression a ≥50% increase in proteinuria to at least 1g/day).
A total of 176 consecutive patients were included (figure). Median follow-up was 10 years (95% CI: 9–19 years). Ninety-six (54%) patients experienced organ progression: cardiac in 46 (48%), renal in 36 (38%) and both in 14 (14%). The dFLC cutoffs best predicting organ progression were increase to >10% from the value observed at diagnosis [area under the ROC curve (AUC) 0.89 (95% CI: 0.83–0.93)], and >15 mg/L from nadir [AUC 0.84 (95% CI: 0.77–0.89)]. The proposed hematologic progression criterion is an increase in dFLC that is both >10% of the value at diagnosis and >15mg/L than the best response value. Validation is ongoing in the Heidelberg series.



Proposed hematologic progression criterion in patients with AL amyloidosis OA19 (#475)

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.