At least partial hematological response after first cycle of treatment predicts organ response and long-term survival for patients with AL amyloidosis receiving bortezomib-based treatment.

AL amyloidosis is a rare plasma cell dyscrasia characterized by multi-organ involvement and poor prognosis. We retrospectively evaluated the organ response (OR) and long-term survival of newly diagnosed AL amyloidosis patients who received first-line bortezomib-containing induction therapy, aiming to identify the clinical indication of a 50% reduction in the difference between involved and uninvolved free light chains (dFLC) after first cycle of treatment. Among the 89 patients included, 78.7% had cardiac involvement and 42.7% were diagnosed with 2004 Mayo stage III disease, while 75.3% of patients achieved a hematological response, including 37.1% with complete response and a median response time of 1 month. Cardiac and renal responses were observed in 44.3 and 53.1% of patients, respectively. Sixty-one (68.5%) patients achieved at least 50% reduction in dFLC after the first cycle of therapy. After a median follow-up duration of 12 months, the estimated 3-year progression-free survival (PFS) and overall survival (OS) rates were 61.3 and 61.7% respectively. At least 50% reduction in dFLC after the first cycle of therapy was predictive of achieving an OR (p = 0.002), as well as superior PFS (HR = 0.119; 95% CI = 0.045-0.313; p < 0.001) and OS (HR = 0.206; 95% CI = 0.078-0.541; p = 0.001). Additionally, the median PFS and OS were not reached for patients with rapid reduction of dFLC. These results demonstrated that early reduction of dFLC after the first cycle of treatment is predictive of achieving an OR and long-term survival in AL patients receiving bortezomib.