Manufacture of CD22 CAR T cells following positive versus negative selection results in distinct cytokine secretion profiles and γδ T cell output.

Chimeric antigen receptor T cells (CART) have demonstrated curative potential for hematological malignancies, but the optimal manufacturing has not yet been determined and may differ across products. The first step, T cell selection, removes contaminating cell types that can potentially suppress T cell expansion and transduction. While positive selection of CD4/CD8 T cells after leukapheresis is often used in clinical trials, it may modulate signaling cascades downstream of these co-receptors; indeed, the addition of a CD4/CD8-positive selection step altered CD22 CART potency and toxicity in patients. While negative selection may avoid this drawback, it is virtually absent from good manufacturing practices. Here, we performed both CD4/CD8-positive and -negative clinical scale selections of mononuclear cell apheresis products and generated CD22 CARTs per our ongoing clinical trial (NCT02315612NCT02315612). While the selection process did not yield differences in CART expansion or transduction, positively selected CART exhibited a significantly higher in vitro interferon-γ and IL-2 secretion but a lower in vitro tumor killing rate. Notably, though, CD22 CART generated from both selection protocols efficiently eradicated leukemia in NSG mice, with negatively selected cells exhibiting a significant enrichment in γδ CD22 CART. Thus, our study demonstrates the importance of the initial T cell selection process in clinical CART manufacturing.

Unlocking antitumor immunity with adenosine receptor blockers.

Tumors survive by creating a tumor microenvironment (TME) that suppresses antitumor immunity. The TME suppresses the immune system by limiting antigen presentation, inhibiting lymphocyte and natural killer (NK) cell activation, and facilitating T cell exhaustion. Checkpoint inhibitors like anti-PD-1 and anti-CTLA4 are immunostimulatory antibodies, and their blockade extends the survival of some but not all cancer patients. Extracellular adenosine triphosphate (ATP) is abundant in inflamed tumors, and its metabolite, adenosine (ADO), is a driver of immunosuppression mediated by adenosine A2A receptors (A2AR) and adenosine A2B receptors (A2BR) found on tumor-associated lymphoid and myeloid cells. This review will focus on adenosine as a key checkpoint inhibitor-like immunosuppressive player in the TME and how reducing adenosine production or blocking A2AR and A2BR enhances antitumor immunity.