Prognostic restaging at the time of second-line therapy in patients with AL amyloidosis.

It is well known that staging of patients with AL amyloidosis at diagnosis predicts for survival, but there is a paucity of literature delineating the prognostic value of these systems at relapse. We evaluated the prognostic value of AL staging among 413 patients initiated with second-line therapy between 2000 and 2015. Both the Revised Mayo 2012 and the European revision of Mayo 2004 staging systems were used. The median time from initial treatment to second-line therapy was 11.7 months. The first-line therapy was autologous stem cell transplant (ASCT) in 179 (43%) patients and non-ASCT therapies in 234 patients. Median survival from the institution of second-line therapy was 61 months. Both the Mayo 2004 and 2012 staging systems were of prognostic benefit at second-line therapy with respective risk ratios of 2.78 (95% CI: 2.15, 3.58) and 3.03 (95% CI: 2.33, 3.93) for patients with > stage 2 disease. On multivariate analysis, the predictive value of staging at second-line therapy was independent of stage at diagnosis and prior ASCT as first-line therapy. This study indicates that the Mayo staging systems work well at second-line therapy. Consequently, it is suitable for the stratification of patients in trials for relapsed, refractory AL amyloidosis.

Delineation of the timing of second-line therapy post-autologous stem cell transplant in patients with AL amyloidosis.

Among patients with immunoglobulin light chain (AL) amyloidosis, there is little consensus on when reinstitution of chemotherapy should occur. We conducted a retrospective study to evaluate the patterns of relapse or progression (R/P) and the timing of reinitiating therapy among 235 patients initially treated with autologous stem cell transplant (ASCT) at Mayo Clinic. The median time from ASCT to second-line therapy was 24.3 months. At the time of restarting therapy, median difference of free light chain (dFLC) was 9.9 mg/dL (42% of diagnosis value), 32% had a dFLC <5 mg/dL, and 63% met criteria for organ R/P. The indications for retreatment were (1) clinical suspicion of R/P, 10%; 92) hematologic R/P only, 23%; (3) organ R/P only, 32%; (4) both hematologic and organ R/P, 31%; and (5) suboptimal response to ASCT and second-line therapy as consolidation, 4%. Patients with organ progression at the time of second-line therapy had inferior survival. Although a dFLC of >5 mg/dL at the time of reinstituting therapy was associated with risk, patients relapsing from very good partial response (VGPR) or better had a longer time to develop organ progression after hematologic R/P (24.2 vs 3.2 months, P = .007). These data suggest that the best candidates for clinical trials testing novel plasma cell-directed chemotherapy beyond first line may be those patients who are either relapsing from VGPR or better (dFLC at diagnosis was >5 mg/dL) or having inadequate response to prior therapy. This strategy should allow for hematologic response assessment while avoiding the risk of deleterious organ progression. Implementation of more stringent progression criteria may also be warranted.