Intermediate‐dose intravenous melphalan and blood stem cells mobilized with sequential GM+G‐CSF or G‐CSF alone to treat AL (amyloid light chain) amyloidosis

AL amyloidosis patients ineligible for dose-intensive melphalan (200 mg/m2) were enrolled on a phase 11 trial to be treated with two cycles of intermediate-dose melphalan (IDM 100 mg/m2) and mobilized blood stem cells (BSC). For mobilization patients were randomized to either GM-CSF 250 microg/m2 for 3 d followed by G-CSF 10 microg/ kg for 3 d (GM+G), or G-CSF 10 microg/kg for 6 d (G-alone), with leukaphereses on days 5, 6 and 7. To minimize morbidity, we planned to support each cycle with 3 5 x 106 CD34+ cells/kg and had a collection target of 7 x 10(6) CD34+ cells/kg. Those who did not achieve the target were treated with one cycle of IDM. 30 patients, a median of 62 years old and 7 months from diagnosis, were enrolled. Both mobilization regimens were generally well tolerated, and similar in terms of CD34+ cells and CFU-GM collected, but only 6/28 patients achieved the collection target (GM+G four, G-alone two). Despite a 19% incidence of grade 4 toxicities, IDM therapy was well tolerated. At a median follow-up of 24 months (19-36) 57% of patients had survived, 17% with durable complete haematological responses and 40% with improved or stable amyloid organ involvement, including 3/9 patients with predominant cardiac amyloid who are alive 2-3 years after treatment. The 100 d mortality was 20%. In conclusion, no definitive differences were identified between the mobilization regimens and IDM was an active regimen in AL for selected patients.