Single UM171 Expanded Cord Blood Permits Transplantation of Better HLA Matched Cords with Excellent Gvhd Relapse Free Survival

• Published in: Blood 2018-11, Vol.132 (Supplement 1), p.4658-4658
• Main Authors: Cohen, Sandra, Roy, Jean, Lachance, Silvy, Marinier, Anne, Delisle, Jean-Sébastien, Roy, Denis-Claude, Busque, Lambert, Ahmad, Imran, Bambace, Nadia M., Barabe, Frederic, Bernard, Léa, Kiss, Thomas L., Bouchard, Philippe, Caudrelier, Pierre, Larochelle, Fannie, Lemieux, Sébastien, Tanguay, Mégane, Chagraoui, Jalila, Zandstra, Peter W., Sauvageau, Guy
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2018-99-110188

Cord blood (CB) transplants have fallen into disfavor in large part due to low cell dose leading to prolonged hospitalizations and high transplant related mortality (TRM). UM171, a novel and potent agonist of hematopoietic stem cell (HSC) self-renewal could solve this major limitation, allowing for CB's important qualities of lower risk of chronic GVHD and relapse to prevail. In addition, UM171 could permit transplantation of smaller, better HLA matched cords, associated with lower TRM. Hence, we initiated a clinical trial to test the safety and efficacy of UM171 expanded CB (eCB). Our goal was to design a clinically viable eCB transplant with a TRM as low or lower than other HSC sources all the while maintaining CB's low relapse rate. Patients (pts) received a myeloablative conditioning regimen. On day (D)-7 of transplant, CB was thawed and CD34+ selected. The CD34- lymphocyte containing fraction was cryopreserved and infused on D+1. The CD34+ component was placed in a closed culture system with UM171 and media was injected once a day until D0, when cells were washed and infused. This fed-batch culture system allowed for small culture volumes, saving cost and labor. Between 7/16-6/18, 21 adult pts (median age 44 years) were transplanted with an eCB. Median final culture volume and net viable CD34 fold expansion were 670 mL and 35, respectively. Median 1st day of 100 and 500 neutrophils were D+10 and D+18, respectively. Achieving 100 neutrophils was 5 days faster than seen with our pts receiving peripheral blood (PB) or marrow (BM) and appeared cell dose independent, suggesting that clinically meaningful expansion of an early repopulating myeloid progenitor is at saturation even with smaller CBs. In contrast, attaining 500 neutrophils was accelerated but dependent on cell dose. More importantly, pts appeared to derive clinical benefit beyond neutrophil engraftment (defined as 500 neutrophils). Pts' median last day of fever prior to 500 neutrophils was D+8, much earlier than engraftment and 4 days earlier than seen with our PB-BM pts. We offer 2 hypotheses as explanation: i) 100 neutrophils, which are attained early, provide significant defense against infection, ii) the graft contains a significant proportion of dendritic cell precursors (30-40%) which offer mucosal protection during severe neutropenia. Duration of hospitalization was shorter by 12 days and longer by 2 days compared to our non eCB and PB-BM transplants, respectively. In addition, because c