Costimulation Through the CD137/4-1BB Pathway Protects Human Melanoma Tumor-infiltrating Lymphocytes From Activation-induced Cell Death and Enhances Antitumor Effector Function

Abstract

Adoptive T-cell therapy (ACT) using expanded tumor-infiltrating lymphocytes (TIL) with high-dose IL-2 is a promising form of immunotherapy for Stage IV melanoma having clinical response rates of 50% or more. One of the major problems preventing further success of this therapy is that the current protocols used to highly expand TIL for infusion drive CD8+ T cells to differentiate into effector cells losing key co-stimulatory molecules such as CD28 and CD27. This has been associated with a lack of persistence in vivo for reasons not entirely clear. In this study, we demonstrate that while human melanoma CD8+ TIL lost CD27 and CD28 expression during the rapid expansion for ACT, they gained expression of the alternative co-stimulatory molecule CD137/4-1BB, and to a lesser extent CD134/OX40. Post-REP TIL were found to be highly sensitive to activation-induced cell death (AICD) when re-activated through the TCR with low levels of OKT3 antibody. However, co-ligation of 4-1BB using two different agonistic anti-4-1BB antibodies potently prevented AICD of post-REP CD8+ TIL, including those specific for MART-1, and facilitated even further cell expansion. This was correlated with increased levels of bcl-2 and bcl-xL together with decreased bim expression. 4-1BB-co-stimulated post-REP TIL also expressed increased levels of the cytolytic granule proteins and exhibited enhanced CTL activity against melanoma cells. Lastly, post-REP CD8+ TIL were protected from cell death by anti-4-1BB ligation when exposed to HLA-matched melanoma cells. Our results indicate that 4-1BB co-stimulation may significantly improve TIL survival during melanoma ACT and boost anti-tumor cytolytic activity.

Focusing and sustaining the antitumor CTL effector killer response by agonist anti-CD137 mAb

“…First, CD137 expression can be used for immunomagnetic selection of tumor reactive TILs (38), and subsequent culture of T cells in the presence of CD137 renders more efficacious phenotypic features (39,40). Second, the effector performance (11), survival (10), and memory differentiation (41) can be enhanced by coadministration of the agonist antibody in vivo.…”

Immunotherapy of Cancer with 4-1BB

“…This can lead to reduced in vivo persistence after adoptive transfer (27). Hernandez-Chacon and colleagues (28) observed that ex vivo expansion of TILs resulted in loss of CD27 and CD28 expression but gain of 4-1BB expression and, to a lesser extent, CD134/OX40 (28). Stimulation of these cells with agonistic anti-4-1BB mAbs significantly inhibited their AICD, enhanced their cell division, and increased their cytolytic activity against melanoma cells (28).…”

“…Hernandez-Chacon and colleagues (28) observed that ex vivo expansion of TILs resulted in loss of CD27 and CD28 expression but gain of 4-1BB expression and, to a lesser extent, CD134/OX40 (28). Stimulation of these cells with agonistic anti-4-1BB mAbs significantly inhibited their AICD, enhanced their cell division, and increased their cytolytic activity against melanoma cells (28). Similarly, stimulation of human CD3þCD56þ NK cells with anti-4-1BB increased their cytolytic activity, as shown by their ability to lyse A549 tumor cells (29).…”

Anti-CD137 monoclonal antibodies and adoptive T cell therapy: a perfect marriage?

“…Administration of anti-CD137 mAbs to mice which had been TIL adoptively transferred results in synergistic effects. This is mainly mediated by costimulation of the infused T lymphocytes [25], but also by enhancing T cell entry into malignant tissue through a direct proinflammatory effect on tumor-associated endothelial cells that ectopically express CD137 [26]. 4.…”