Citrulline Trajectory during Allogeneic Hematopoietic Stem Cell Transplantation Is Correlated to Conditioning Intensity and Non-Relapse Mortality

• Published in: Blood 2020-11, Vol.136 (Supplement 1), p.32-33
• Main Authors: Nunes Gomes, Christopher, Seegers, Valerie, Schmidt, Aline, Orvain, Corentin, Villate, Alban, Bouvier, Anne, Simard, Gille, Sutra Del Galy, Aurélien, Francois, Sylvie, Giltat, Aurelien, Robin, Jean Baptiste, Delneste, Yves, Ifrah, Norbert, Hunault, Mathilde, Thepot, Sylvain
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2020-141390

Introduction Citrulline, a non-essential amino acid produced exclusively by enterocytes in the small intestine and involved in the synthesis of L-arginine, is not metabolized by the liver. Therefore citrulline serum concentration is highly correlated with functional enterocyte mass, and decreases with digestive toxicity induced by conditioning therapy (radiotherapy and/or chemotherapy) for hematopoietic stem cell transplantation (HSCT) . Acute Graft-versus-host disease (GvHD), one of the major complications of HSCT, is correlated to conditioning-induced gut barrier damage and may be predicted by pre-transplant serum citrulline level (Rashidi, BBMT 2018). It could be interesting to know whether citrulline kinetics could also represent a biomarker for conditioning toxicity, non-relapse mortality (NRM), and GvHD. The aim of this study is thus to define group-based trajectory modeling, to identify clusters of individual serum citrulline kinetics in the early phase of allogeneic HCST, and to test whether these unsupervised trajectories were correlated with these early complications. Materials and Methods Serum citrulline was quantified by liquid chromatography in blood samples collected from consecutive patients who received an allogeneic HSCT in our institution between July 2014 and November 2019. These samples were drawn at different time-points: pre-transplant (D-7, D-3); day of transplant (D0), and post-transplant (D7, D15, D21). Distinct trajectories were identified for serum citrulline by using the semiparametric mixture model described by Nagin (Nagin, Stat Methods Med Res 2018). Results Among 161 patients (pts) included in the study, with a median age of 53 years (17-72), 98 pts (60.9%) received a reduced-intensity conditioning (RIC), 36 pts (22.4%) reduced-toxicity conditioning (RTC), 18 pts (11.1 %) sequential conditioning, and 9 pts (5.6%) myeloablative conditioning (MAC). Donor were identical sibling (22%), matched unrelated donor (52%) and haploidentical sibling (25%). Graft source was peripheral blood mononuclear cells in 144 pts (89.4%) and bone marrow in 17 pts (10.6%) respectively. HCT-CI score was low, intermediate and high-risk in 38%, 32%, and 30% of pts respectively. Disease-Risk Index (DRI) was low/intermediate in 111 pts (69%) and high/very-high in 50 pts (31%). With a median follow up of 29.1 month, 3-year overall survival (OS), disease-free survival (DFS), and NRM rates were 64.5%, 58.3%, and 18.9%, respectively. The median number of ci