Second Autologous Peripheral Blood Stem Cell Transplantation with High Dose Melphalan (HDM/SCT) in Patients Relapsing After An Initial Course of HDM/SCT for the Treatment of AL Amyloidosis.

Abstract

Abstract 2318Poster Board II-295High-dose melphalan and autologous stem cell transplant (HDM/SCT) can induce complete hematologic responses (CR), defined as disappearance of the underlying monoclonal gammopathy from serum and urine by immunofixation electrophoresis, and of the clonal plasma cell dyscrasia by bone marrow immunohistochemistry, and extend survival in patients with AL amyloidosis. HDM/SCT results in a CR in 40% of patients, and leads to clinical improvements in organ function in >70% of those who achieve a CR. However, hematologic and clinical relapses occur in ∼8% of patients who initially achieve a CR. Tandem cycles of HDM/SCT, which are typically performed within 12 months of each other, have been shown to achieve a higher ultimate CR rate of >60%. Among patients who do not achieve a CR following a single cycle of HDM/SCT, 30% nonetheless experience improvement in organ function. However, in this latter group, clinical improvement is not durable. We designed a study to explore the feasibility, and efficacy, of a second cycle of HDM/SCT in patients who relapse after initially responding to a first cycle of HDM/SCT. Results:Eleven patients, median age 55 (range 39-62), M:F 7:4, who had achieved hematologic and clinical responses after an initial cycle of HDM/SCT, were treated with a second cycle of HDM/SCT when a hematologic and/or clinical relapse occurred after a median time interval of 34 months (range 12-63). Five patients underwent a second course of G-CSF mobilization and a mean of 5.1 million (range 3.4-7.6 million) CD34 cells/kg was collected in a median of 2 days; the other patients had cells saved from the first mobilization. Six patients received 200 mg/m2 HDM; 5 patients received modified high-dose HDM at 140 mg/m2. Engraftment occurred at a median of 10 days for neutrophils, and 12 days for platelets (two days without platelet transfusion support); this engraftment timing is similar to that following the initial transplants (10 days for neutrophils, 13 days for platelets). There was no treatment-related mortality, but toxicity was moderate; almost all patients (except one) experienced grade III/IV non-hematologic toxicities. Of the 11 patients, 3 achieved hematologic CR at one year; these patients are alive and in continuous remission at 2-6 yr after the second transplant, including one patient who received a subsequent renal transplant. Three patients died of progressive disease at 1-2 years after the second transplant. Five patients are alive at 1-3 years post second transplant, in partial remission. Conclusion:27% (3/11) of patients with AL amyloidosis who experience a hematologic or clinical relapse after responding to initial HDM/SCT can achieve a hematologic CR with a second course of HDM/SCT. Disclosures:No relevant conflicts of interest to declare.