1. ¹Department of Medicine, Section of Hematology/Oncology, Boston Medical Center, Boston, MA, USA
2. ²Department of Laboratory Medicine, Boston Medical Center, Boston, MA, USA
3. ³Amyloid Treatment and Research Program, Boston Medical Center, Boston, MA, USA

Correspondence: Dr V Sanchorawala, Section of Hematology/Oncology, F 302, 732 Harrison Avenue, Boston, MA 02118, USA. E-mail: Vaishali.Sanchorawala@bmc.org

Received 22 April 2005; Accepted 20 June 2005; Published online 25 July 2005.

Abstract

Serum free light-chain (FLC) concentrations were measured by a sensitive nephelometric immunoassay in 66 patients with AL amyloidosis before and after treatment with high-dose melphalan and autologous stem cell transplantation (HDM/SCT). At 1 year after HDM/SCT, 27 patients (41%) achieved a complete hematologic response (CR), that is, disappearance of the monoclonal gammopathy previously evident by immunofixation electrophoresis (IFE) in serum and urine and of plasma cell clonality in the bone marrow. Abnormally elevated FLC levels became normal in 27 patients (41%), and decreased by >90% in 37 (56%). Average improvements in FLC were 94% for patients who achieved a CR and 72% for those who did not (P=0.0001). However, a reduction in FLC of >90% was associated with a similar high likelihood of clinical improvement and prolonged survival, whether or not patients achieved a CR. While CR, as defined by standard criteria, is a more stringent indicator of hematologic response than are decreases in abnormally elevated FLC levels per se, these measures of hematologic response are complementary, and decreases in FLC are more readily detected early after treatment than are the changes in IFE and marrow studies required to determine CR.