P-024: Early relapse is an adverse prognostic marker in systemic immunoglobulin light chain (AL) Amyloidosis

Background Systemic Immunoglobulin light chain amyloidosis (AL) is a protein-misfolding disorder associated with an underlying monoclonal B-cell or plasma cell dyscrasia. There is little information on how response durability impacts outcomes. It is conceivable that early relapse may confer an adverse prognosis in AL, like in Myeloma. Here, we test the above hypothesis and analyse the factors affecting response durability in a cohort of AL patients treated with frontline Bortezomib. Methods All patients treated with frontline Bortezomib in 2010-2019 are included in the analysis. Patients with primary refractory disease, those with a continuing response but ≤ 24 months follow up, and those who received 2nd line therapy for reasons other than progression are excluded from the analysis. We defined early relapse (ER) as PFS ≤ 24 months. Results 560 patients are included in this analysis. 250 (44.6%) and 310 (55.4%) patients had ER and LR, respectively. The ER group had more advanced cardiac disease (p 20% (p=0.021), ≥ VGPR after 1st line (p 20%, and dFLC Conclusions In conclusion, these data identify a high-risk group of patients who relapse early and have a poorer survival (irrespective of their initial response). The depth of response to the initial treatment is a critical determinant of response durability. The early relapses should be considered for clinical trials that can identify treatments with the potential to overcome the high-risk biology of the disease.