Abstract: Objective: To  investigate  the  efficacy  and  safety  of  propylene  glycol  free  melphalan  in  autologous hematopoietic stem cell transplantation （ASCT）for patients with systemic light chain （AL）amyloidosis.    Methodology:A total of 352 patients with AL amyloidosis  who  received ASCT from 2010  to 2023  were  retrospectively  included， including 127 patients with propylene glycol  free  melphalan pretreatment  （group A）， 225 patients  with propylene  glycol  melphalan pretreatment （group  B）.  The  safety  of  treatment  and  short-term  hematological  response  rate  after  transplantation  were compared between the two groups.    Results:There were no differences in age， type of light chain involved， neutrophil and platelet engraftment time， and  group  A  patients  had  a  lower  proportion  of  cardiac  involvement  but  a  higher  proportion  of bone marrow plasma cells. The overall hematological response rate （89.4%  vs 73.4%， P = 0.001） and complete response rate （39.4%  vs 24%， P = 0.005） at 3 months after transplantation in group A were higher than those in group B， which may be related to the fact that more patients in group A （79.5%） received proteasome  inhibitor  induction therapy  before transplantation. Group A had a higher  incidence  of  grade  3 ~ 4  diarrhea  （11.8%  vs  2.7%，  P < 0.001） and  nausea  and vomiting （67.7% vs 35.1%， P<0.001）. There were no differences in infection， cardiac and renal toxicity between the two groups. The incidences of implantation  syndrome  （2.4%  vs  7.6%，  P = 0.043） and  mucositis  （27.6%  vs  46.7%，  P < 0.001） were  lower  in  the  group  A，  and  no  grade  3  or  higher  mucositis  occurred.     Conclusion: The  preconditioning regimen of propylene glycol  free  melphalan  is  well  tolerated  and  effective  in  the  treatment  of  ASCT  for  patients  with  AL amyloidosis.

Key words: propylene glycol free melphalan, systemic light chain amyloidosis, efficacy, safety