Work

Mitigating Damage Response with CD24 Fusion Protein for Prevention of Acute Graft-Versus-Host Disease

Year: 2020

Type: article

Abstract: Danger-associated molecular patterns (DAMPs) released during conditioning have been shown to amplify experimental GVHD. CD24 fusion protein (CD24Fc; OncoImmune), a glycoprotein linked to human IgG 1 Fc, binds to Siglec-10 to negatively regulate host response to DAMPs. We have reported that infusion of CD24Fc prior to HCT significantly decreased GVHD-related mortality in murine models of HCT (Toubai, Blood 2015 & Toubai, JCI Insight 2017). We hypothesized that enhancing Siglec10-CD24 interactions by administration of CD24Fc would prevent acute GVHD. A randomized, prospective, multi-site, placebo controlled phase 2a clinical trial was initiated to investigate safety of three dose levels of CD24Fc (or blinded placebo) plus standard GVHD prophylaxis with tacrolimus and methotrexate (MTX) in matched unrelated donors. T cell replete PBSC or BMT was infused. Randomization (3:1 ratio of CD24Fc:Placebo) was in 3 cohorts of 8 pts: 240mg single dose on D -1, 480mg single dose on D -1, and a 480mg, 240mg, and 240mg multiple dose regimen on D -1, 14 and 28, respectively. The primary endpoint was safety and determination of a recommended dose. Pts were followed for secondary endpoints of aGVHD, relapse and survival at D180. The trial enrolled 24 pts (CD24Fc, n=18; Placebo, n=6) with minimum follow up on one year (Table1). All planned dosages were administered without reaching an MTD. There were no infusion-related toxicities or DLTs. In placebo treated pts, there was one DLT resulting in death from pneumonia. Between groups there were no overall differences in AEs, although CD24Fc was associated with fewer days of severe (≥ Grade III) mucositis. There was no infection-related mortality related to CD24Fc treatment. The CD24Fc pts achieved neutrophil and platelet engraftment at a median of D 13 (12-23) and D 13 (9-23), respectively. PK studies demonstrated sustained drug levels through D 100 in the multi-dosing cohort. The incidence of grade II-IV GVHD was 39% (18-62%) and III-IV GVHD was 6% (95% CI 0-20%) at D 180 among CD24Fc treated pts. Grade 3 involvement of the lower-GI tract was observed in 1/18 pts, while the remainder of acute GVHD involved the upper GI tract or skin. All pts receiving treatment for GVHD experienced response. At D 180, relapse occurred in 2/18 pts, and OS was 100%. The endpoint of grade 3-4 GVHD-free survival (AGFS) was 94% at D 180 in pts receiving treatment with CD24Fc versus 50% in pts receiving placebo (HR 0.1; 90% CI 0.0-0.7). AGFS in contemporaneous case matched controls (n=68; CIBMTR) receiving myeloablative 8/8 HLA matched unrelated donor HCT with tacrolimus + MTX was 68% (95% CI: 56-78). In this translational phase 2a trial administration of CD24Fc was safe and tolerable. Additional investigations are required determine efficacy for improving AGFS after HCT. This trial represents the first attempt to prevent GVHD by inhibiting host response to DAMPs.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2019.12.126