Intratumoral antigen signaling traps CD8+ T cells to confine exhaustion to the tumor site.

Immunotherapy advances have been hindered by difficulties in tracking the behaviors of lymphocytes after antigen signaling. Here, we assessed the behavior of T cells active within tumors through the development of the antigen receptor signaling reporter (AgRSR) mouse, fate-mapping lymphocytes responding to antigens at specific times and locations. Contrary to reports describing the ready egress of T cells out of the tumor, we find that intratumoral antigen signaling traps CD8+ T cells in the tumor. These clonal populations expand and become increasingly exhausted over time. By contrast, antigen-signaled regulatory T cell (Treg) clonal populations readily recirculate out of the tumor. Consequently, intratumoral antigen signaling acts as a gatekeeper to compartmentalize CD8+ T cell responses, even within the same clonotype, thus enabling exhausted T cells to remain confined to a specific tumor tissue site.

The S enantiomer of 2-hydroxyglutarate increases central memory CD8 populations and improves CAR-T therapy outcome.

Cancer immunotherapy is advancing rapidly and gene-modified T cells expressing chimeric antigen receptors (CARs) show particular promise. A challenge of CAR-T cell therapy is that the ex vivo-generated CAR-T cells become exhausted during expansion in culture, and do not persist when transferred back to patients. It has become clear that naive and memory CD8 T cells perform better than the total CD8 T-cell populations in CAR-T immunotherapy because of better expansion, antitumor activity, and persistence, which are necessary features for therapeutic success and prevention of disease relapse. However, memory CAR-T cells are rarely used in the clinic due to generation challenges. We previously reported that mouse CD8 T cells cultured with the S enantiomer of the immunometabolite 2-hydroxyglutarate (S-2HG) exhibit enhanced antitumor activity. Here, we show that clinical-grade human donor CAR-T cells can be generated from naive precursors after culture with S-2HG. S-2HG-treated CAR-T cells establish long-term memory cells in vivo and show superior antitumor responses when compared with CAR-T cells generated with standard clinical protocols. This study provides the basis for a phase 1 clinical trial evaluating the activity of S-2HG-treated CD19-CAR-T cells in patients with B-cell malignancies.

Early loss of Crebbp confers malignant stem cell properties on lymphoid progenitors.

Loss-of-function mutations of cyclic-AMP response element binding protein, binding protein (CREBBP) are prevalent in lymphoid malignancies. However, the tumour suppressor functions of CREBBP remain unclear. We demonstrate that loss of Crebbp in murine haematopoietic stem and progenitor cells (HSPCs) leads to increased development of B-cell lymphomas. This is preceded by accumulation of hyperproliferative lymphoid progenitors with a defective DNA damage response (DDR) due to a failure to acetylate p53. We identify a premalignant lymphoma stem cell population with decreased H3K27ac, which undergoes transcriptional and genetic evolution due to the altered DDR, resulting in lymphomagenesis. Importantly, when Crebbp is lost later in lymphopoiesis, cellular abnormalities are lost and tumour generation is attenuated. We also document that CREBBP mutations may occur in HSPCs from patients with CREBBP-mutated lymphoma. These data suggest that earlier loss of Crebbp is advantageous for lymphoid transformation and inform the cellular origins and subsequent evolution of lymphoid malignancies.

CTLA4Ig alters the course of autoimmune disease development in Lyn-/- mice.

Lyn-deficient (Lyn(-/-)) mice develop an age-dependent autoimmune disease similar to systemic lupus erythematosus, characterized by the production of IgG anti-nuclear Ab. To determine the extent to which this autoimmune phenotype is driven by T cell costimulation, we generated Lyn(-/-) mice expressing a soluble form of the T cell inhibitory molecule, CTLA4 (CTLA4Ig). Surprisingly, although CTLA4Ig prevented myeloid hyperplasia, splenomegaly and IgG anti-nuclear Ab production in Lyn(-/-) mice, it did not inhibit immune complex deposition and tissue destruction in the kidney. In fact, regardless of CTLA4Ig expression, Lyn(-/-) serum contained elevated titers of IgA anti-nuclear Ab, although generally IgA deposition in the kidney was only revealed in the absence of self-reactive IgG. This demonstrated that activation of autoreactive B cell clones in Lyn(-/-) mice can still occur despite impaired costimulation. Indeed, CTLA4Ig did not alter perturbed Lyn(-/-) B cell development and behavior, and plasma cell frequencies were predominantly unaffected. These results suggest that when self-reactive B cell clones are unimpeded in acquiring T cell help, they secrete pathogenic IgG autoantibodies that trigger the fulminant autoimmunity normally observed in Lyn(-/-) mice. The absence of these IgG immune complexes reveals an IgA-mediated axis of autoimmunity that is not sufficient to cause splenomegaly or extramedullary myelopoiesis, but which mediates destructive glomerulonephritis. These findings have implications for the understanding of the basis of Ab-mediated autoimmune diseases and for their treatment with CTLA4Ig.