Wharton’s jelly MSCs in high-risk and SR-aGvHD: Phase Ib trial results

Results from a prospective, single-center, open-label, phase Ib trial (NCT03158896), evaluating the safety and preliminary efficacy of MSCTC-0010, a Wharton’s jelly mesenchymal stromal cell (MSC) product, in adults with steroid-refractory (SR) or high-risk (HR) acute graft-versus-host disease (aGvHD; N = 24), were published in Cytotherapy by Wesson et al. Patients received intravenous MSCTC-0010 at 2 × 10⁶ cells/kg (low dose; n = 5) or 10 × 10⁶ cells/kg (high dose; n = 5) on Days 0 and 7, or 10 × 10⁶ cells/kg on Days 0, 7, 14, and 21 (extended high dose; n = 14). The primary endpoint was absence of treatment-related adverse events (TRAEs), defined as Grade ≥3 adverse events (AEs) related to MSCTC-0010 persisting >24 hours, by Day 42.

Key data: No patients experienced a TRAE persisting >24 hours following MSCTC-0010 infusion; one patient experienced transient infusion-related dyspnea. Day-28 ORR was 71% (complete response [CR], 33%; partial response [PR], 38%); Day-90 ORR was 54% (CR, 42%; PR, 13%). Within 90 days, 75% of patients required additional immunosuppression (all received ruxolitinib; 25% also received extracorporeal photopheresis [ECP]), initiated at a median of 15 days post-infusion. Median overall survival (OS) was 7.0 months (interquartile range [IQR], 1.5 months–not reached [NR]) overall and 30 months (IQR, 4.5 months–NR) among patients completing all planned doses. 

Key learning: MSCTC-0010 demonstrated a favorable safety profile and early efficacy in patients with HR- or SR-aGvHD, supporting its continued investigation to define its clinical benefit in this population with historically poor outcomes.