Citation: Biology of Blood and Marrow Transplantation. 2019, 25(3), S255-S256
Author: John E.J. Rasko, Amit Patel, James E. Griffin, Maria H. Gilleece, Rohini Radia, David T. Yeung, Igor Slukvin, Kilian Kelly, Adrian J Bloor,
Abstract: Mesenchymal stem cells (MSCs) have been widely investigated as a treatment for graft versus host disease (GvHD), but with mixed results. Factors such as MSC donor variability and the effects of prolonged culture expansion may have contributed to disappointing outcomes. The novel Cymerus™ manufacturing process facilitates virtually limitless production of well-defined and consistent MSCs from a single iPSC bank, using proprietary clonogenic progenitor-based technology. This avoids both inter-donor variability and the need for excessive culture expansion once MSCs are formed. This is a multi-center, open label study of Cymerus MSCs (CYP-001) in adults with steroid-resistant acute GvHD, following allogeneic hematopoietic stem cell transplantation (NCT02923375). Prior to enrolment, all subjects had failed to respond to at least three days of steroid treatment (≥1 mg/kg/day), administered in accordance with standard management at each center. Subjects received two intravenous infusions of CYP-001 one week apart, at a dose of 1 × 106 cells/kg (Cohort A) or 2 × 106 cells/kg (Cohort B), in addition to standard of care medications. The study involves follow-up over two years, with primary evaluation at 100 days. GvHD was staged and graded according to the 1994 Consensus Conference on Acute GvHD Grading. An Overall Response (OR) was defined as at least a one-grade improvement in GvHD severity, while a Complete Response (CR) was defined as the absence of any GvHD signs or symptoms. The primary objective was assessment of safety and tolerability, while the secondary objective was efficacy, based on overall survival (OS) and best responses by Day 28/Day 100. Eight subjects were enrolled per cohort, but one subject in Cohort B withdrew prior to the initiation of CYP-001 treatment. All subjects had Grade II or III GvHD at baseline. The treatment was well tolerated in all cases, and there were no treatment-related Serious Adverse Events (SAEs) reported. One patient in Cohort A died after developing pneumonia, which was not considered to be CYP-001 treatment-related. One patient in Cohort B did not show a response to CYP-001 treatment, and withdrew from the trial on Day 22 to commence palliative care. All other patients showed an OR and remained alive at Day 100. Overall, outcomes by Day 100 were similar in both cohorts, but Day 28 data suggest a faster response to the higher dose level used in Cohort B (see Table 1 and Figure 1). In conclusion, CYP-001 infusions were found to be safe and well tolerated in this study, and we believe the encouraging treatment response and overall survival rates support progression to a Phase II trial.
