Combination CTLA-4 blockade and 4-1BB activation enhances tumor rejection by increasing T-cell infiltration, proliferation, and cytokine production.

Abstract

BACKGROUND:

The co-inhibitory receptor Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) attenuates immune responses and prevent autoimmunity, however, tumors exploit this pathway to evade the host T-cell response. The T-cell co-stimulatory receptor 4-1BB is transiently upregulated on T-cells following activation and increases their proliferation and inflammatory cytokine production when engaged. Antibodies which block CTLA-4 or which activate 4-1BB can promote the rejection of some murine tumors, but fail to cure poorly immunogenic tumors like B16 melanoma as single agents.

METHODOLOGY/PRINCIPAL FINDINGS:

We find that combining αCTLA-4 and α4-1BB antibodies in the context of a Flt3-ligand, but not a GM-CSF, based B16 melanoma vaccine promoted synergistic levels of tumor rejection. 4-1BB activation elicited strong infiltration of CD8+ T-cells into the tumor and drove the proliferation of these cells, while CTLA-4 blockade did the same for CD4+ effector T-cells. Anti-4-1BB also depressed regulatory T-cell infiltration of tumors. 4-1BB activation strongly stimulated inflammatory cytokine production in the vaccine and tumor draining lymph nodes and in the tumor itself. The addition of CTLA-4 blockade further increased IFN-γ production from CD4+ effector T-cells in the vaccine draining node and the tumor. Anti 4-1BB treatment, with or without CTLA-4 blockade, induced approximately 75% of CD8+ and 45% of CD4+ effector T-cells in the tumor to express the killer cell lectin-like receptor G1 (KLRG1). Tumors treated with combination antibody therapy showed 1.7-fold greater infiltration by these KLRG1+CD4+ effector T-cells than did those treated with α4-1BB alone.

CONCLUSIONS/SIGNIFICANCE:

This study shows that combining T-cell co-inhibitory blockade with αCTLA-4 and active co-stimulation with α4-1BB promotes rejection of B16 melanoma in the context of a suitable vaccine. In addition, we identify KLRG1 as a useful marker for monitoring the anti-tumor immune response elicited by this therapy. These findings should aid in the design of future trials for the immunotherapy of melanoma.

• Authors: Michael A Curran, Myoungjoo Kim, Welby Montalvo, Aymen Al-Shamkhani, James P Allison
• Journal: PloS one (PLoS One) Vol. 6 Issue 4 Pg. e19499 (Apr 29 2011) ISSN: 1932-6203 [Electronic] United States
• PMID: 21559358 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antigens, Differentiation
• Antineoplastic Agents
• CTLA-4 Antigen
• Cytokines
• Klrg1 protein, mouse
• Lectins, C-Type
• Pdcd1 protein, mouse
• Programmed Cell Death 1 Receptor
• Receptors, Immunologic
• Tumor Necrosis Factor Receptor Superfamily, Member 9
• Interferon-gamma
• Ovalbumin

Topics

• Animals
• Antigens, Differentiation (metabolism)
• Antineoplastic Agents (pharmacology)
• Autoimmunity
• CTLA-4 Antigen (chemistry)
• Cell Proliferation
• Cytokines (metabolism)
• Interferon-gamma (metabolism)
• Lectins, C-Type
• Lymph Nodes (pathology)
• Male
• Melanoma, Experimental
• Mice
• Mice, Inbred C57BL
• Neoplasm Transplantation
• Neoplasms (immunology, therapy)
• Ovalbumin (chemistry)
• Programmed Cell Death 1 Receptor
• Receptors, Immunologic (metabolism)
• T-Lymphocytes (cytology)
• Tumor Necrosis Factor Receptor Superfamily, Member 9 (metabolism)