These findings suggest that increased sCTLA4 may contribute in CTLA4-induced suppression of tumor immunity and provide explanations for the widely reported association of CTLA4 gene with cancer.
We found that although treatment with combined anti-CTLA-4 and anti-PD-1 improved control of established tumors, this combination compromised anti-tumor immunity in the low tumor burden (LTB) state in pre-clinical models as well as in melanoma patients.
The discovery that antibody blockade of the T cell co-inhibitory receptor cytotoxic T lymphocyte-associated protein 4 (CTLA-4) can restore tumor immunity against many murine transplantable tumors leading to complete rejection of established cancer forever changed the field of immunotherapy.
Concurrent OX40 and CD30 Ligand Blockade Abrogates the CD4-Driven Autoimmunity Associated with CTLA4 and PD1 Blockade while Preserving Excellent Anti-CD8 Tumor Immunity.
Thus, high ADCC anti-CTLA-4 mAb is able to selectively deplete effector Treg cells and evoke tumor immunity depending on the CTLA-4-expressing status of effector CD8<sup>+</sup> T cells.
Monoclonal antibodies against the immune checkpoints cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1) can restore an efficient and durable anti-tumor immunity, even following treatment discontinuation.
We hypothesized that local delivery of anti-CTLA-4 and anti-GITR mAbs to the sites where T cells and tumor antigen-loaded DC vaccines interact would enhance the induction of anti-tumor immunity while avoiding autoimmunity.
CTLA-4 and PD-1 are the representative examples, and their blockade by therapeutic antibodies leads to enhanced anti-tumor immunity with durable clinical responses, but only in a minority of patients.
Targeting immune checkpoint molecules such as programmed cell death-1 (PD-1) and cytotoxic T lymphocyte-associated protein-4 (CTLA-4) reinvigorates anti-tumor immunity by restoring exhausted T cells.
The enhanced anti-tumor immunity in response to the CD25 depletion or CTLA-4 blockade was only seen in the immunogenic TRAMP-PSA tumor model, whereas the effect was completely absent in mice bearing poorly immunogenic TRAMP-C1 tumors.