Corticosteroids and methotrexate as adjuvants to costimulation blockade in non-human primate renal transplantation.

Belatacept, the CD28-B7 costimulation pathway inhibitor, has been approved as a calcineurin inhibitor (CNI) alternative in kidney transplantation. Although costimulation blockade (CoB) allows for CNI avoidance, it is associated with increased rates of early rejection, prompting a search for agents to pair with belatacept. Methotrexate (MTX) is an antimetabolite that has been found to be complimentary with abatacept, a lower affinity CD28-B7-specific analogue of belatacept, in the treatment of rheumatoid arthritis (RA).

Long-term survival of pig-to-rhesus macaque renal xenografts is dependent on CD4 T cell depletion.

The shortage of available organs remains the greatest barrier to expanding access to transplant. Despite advances in genetic editing and immunosuppression, survival in experimental models of kidney xenotransplant has generally been limited to <100 days. We found that pretransplant selection of recipients with low titers of anti-pig antibodies significantly improved survival in a pig-to-rhesus macaque kidney transplant model (6 days vs median survival time 235 days).

CD28 blockade controls T cell activation to prevent graft-versus-host disease in primates.

Controlling graft-versus-host disease (GVHD) remains a major unmet need in stem cell transplantation, and new, targeted therapies are being actively developed. CD28-CD80/86 costimulation blockade represents a promising strategy, but targeting CD80/CD86 with CTLA4-Ig may be associated with undesired blockade of coinhibitory pathways. In contrast, targeted blockade of CD28 exclusively inhibits T cell costimulation and may more potently prevent GVHD.

Neutralizing human monoclonal antibodies prevent Zika virus infection in macaques.

Therapies to prevent maternal Zika virus (ZIKV) infection and its subsequent fetal developmental complications are urgently required. We isolated three potent ZIKV-neutralizing monoclonal antibodies (nmAbs) from the plasmablasts of a ZIKV-infected patient-SMZAb1, SMZAb2, and SMZAb5-directed against two different domains of the virus. We engineered these nmAbs with Fc LALA mutations that abrogate Fcγ receptor binding, thus eliminating potential therapy-mediated antibody-dependent enhancement.

Belatacept-Resistant Rejection Is Associated With CD28 Memory CD8 T Cells.

Recently, newer therapies have been designed to more specifically target rejection in an effort to improve efficacy and limit unwanted toxicity. Belatacept, a CD28-CD80/86 specific reagent, is associated with superior patient survival and graft function compared with traditional therapy, but its adoption as a mainstay immunosuppressive therapy has been tempered by increased rejection rates. It is essential that the underlying mechanisms associated with this rejection be elucidated before belatacept is more widely used.