Light Chain Deposition Disease: Impact of Stem Cell Tranplant on Hematological Response Achievement.

We retrospectively reviewed the records of all pts treated with HDM/ASCT at Princess Margaret Hospital between January 2004 and December 2009 and identified five pts with LCDD. Pretreatment evaluation included staging investigations: 1) complete blood cell counts, 2) complete biochemistry panel, 3) albumin and β2-microglobulin, 4) Blood and Urinary Monoclonal protein assessment including Free LC Assay; 5) skeletal survey. 6) Bone marrow aspirate and biopsy. Pts with LCDD and concurrent multiple myeloma were excluded. LCDD was diagnosed by renal biopsy in all pts with histology confirming characteristic linear monoclonal LC deposits along the tubular membrane staining for kappa and lambda chains on inmunofluorescence. All pts received induction therapy prior to consolidation with HDM/ASCT [dexamethasone (n=3) and vel plus dexamethasone (n=2)]. Assessment of hematologic response (HR) to treatment was based on modified EORTC consensus criteria.

Pts characteristics are shown in Table 1. Two pts were male subjects; the median age was 55 (range 45–65). All five pts, had elevated serum FLC and an abnormal κ-to- λ ratio. All of the pts presented with kidney involvement. The monoclonal protein deposited in the kidney consisted of free κ-LC in four pts and free lambda LC in 1. Two pts received vel and dexamethasone (3 cycles) induction therapy achieving PR after 6 weeks of therapy and three received dexamethasone alone: 1 pt achieving a PR and 2 SD. All of them received a conditioning regimen of mel 200 mg/m². Complete HR was seen in 3 pts and PR in 1 patient (ORR 80%, CR 60%). Transplanted pts had a median time to ANC ≥0.5 ×10⁹/L of 12d (Range 12–13) and time to platelets ≥ 20 ×10⁹/L was 14 days (Range 12–17). Median time to discharge was 17 days (range 13–30) and no pts exhibited engraftment syndrome. There was no mortality related to transplant. The most common grade 3/4 adverse events included: neutropenic fever (n=5); mucositis (n=2); and transient worsening in kidney function (n=1). All pts are alive and progression-free at a median follow-up of 20 months (range 7–37) from transplant. As kidney dysfunction represents the most prominent morbidity in LCDD, it is important to emphasize that the elevated serum creatinine was ameliorated in these pts after ASCT

LCDD is a rare condition and its management is controversial. In a few small series, investigators have reported that high-dose melphalan (HDM) followed by ASCT can be associated with beneficial results whereas toxicity remains acceptable in this group of pts. We report our experience using HDM and ASCT in pts with LCDD without concurrent myeloma, demonstrating feasibility and tolerability.

Reece:Celgene: Honoraria, Research Funding. Chen:Celgene Corporation: Consultancy, Honoraria, Research Funding. Kukreti:Celgene: Honoraria.