Characterization and prognostic implication of delayed complete response in AL amyloidosis.

INTRODUCTION: Little is known on continued response following completion of therapy in light chain (AL) amyloidosis. METHODS: We studied 373 AL amyloidosis patients who achieved complete response (CR) or very good partial response (VGPR) to first-line therapy. RESULTS: By end of therapy (EOT), 46% of patients achieved a CR and 54% a VGPR. With no further therapy, 17.5% of patients were upstaged from VGPR to CR (delayed CR), with a median of 9 months. Compared with CR and VGPR at EOT, patients with a delayed CR were characterized by higher proportion of t(11;14) and lower rate of trisomies. Autologous stem cell transplant was more frequent in the delayed CR group. Patients with a delayed CR were characterized by minimal residual disease negativity and organ response rates similar to patients with CR at EOT and higher than patients achieving VGPR at EOT. Patients with a delayed CR had a longer PFS/OS compared to patients with CR or VGPR by EOT (median PFS 149 vs 92 vs 52 months, P < .001; 10-year OS 87% vs 71% vs 56%, P < .001). CONCLUSIONS: This study characterizes delayed CR in AL amyloidosis, highlights its prognostic impact which is at least similar to those who achieved CR at EOT, and underlines another aspect of response monitoring.

Bone marrow plasma cells 20% or greater discriminate presentation, response, and survival in AL amyloidosis.

We explored the association between bone marrow plasma cells (BMPCs) and disease presentation and outcome among 1574 AL patients. Three BMPC groups were formulated: <5% (n = 231, 15% of study population), 5-19% (n = 1045, 66%), and ≥20% (n = 298, 19%). Heart and renal involvement were more and less prevalent, respectively, with increasing BMPCs. Patients with ≥20% BMPCs had higher likelihood for classic myeloma phenotype with less skewed lambda restriction, a higher rate of intact immunoglobulin secretion, a lower hemoglobin and higher rates of hypercalcemia and bone lytic lesions. High-risk cytogenetic abnormalities were more common in ≥20% BMPCs. Complete hematological response was less frequent with rising BMPCs. The median survival was inversely associated with the BMPC groups (81, 33, 12 months for <5%, 5-19%, and ≥20% BMPCs, respectively; P < 0.001). Survival discrimination was maintained at 1-year landmark and in those who achieved a complete response. Multivariate analysis accounting for known prognostic markers yielded an independent prognostic role for ≥20% BMPCs, but not for the other BMPC groups. AL patients with 20% or greater BMPCs have poorer outcome independent of their cardiac risk category and stem cell transplant eligibility. Distinct interventions in these patients should be explored to improve outcome.