Triple Immunotherapy Overcomes Immune Evasion by Tumor in a Melanoma Mouse Model

Abstract

Background: Melanoma is a malignancy with increasing incidence that underlies most skin cancer-related deaths. Advanced melanoma patients still have poor prognosis despite recently developed immunotherapies. This study devises a triple immunotherapy to treat melanoma in a mouse model. The combination includes anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) antibodies, Monophosphoryl-lipid-A (MPLA), and an Indolamine-Dioxygenase-1 (IDO1) inhibitor. The aim of the study is, first, to rule out any major toxic effects related to this therapy and, second, to assess its antitumor effects. Methods: Cancer-free C57BL/6 mice were randomized into control groups and groups receiving single, dual, or triple therapies of the defined treatments. Clinical signs, weight gain, and histological sections from their main organs were assessed. Then, melanoma-bearing mice were segregated into similar groups, monitored for survival, and their tumor size was measured repeatedly. Finally, flow cytometry was used to analyze immune cell populations in the tumor masses including CD4+, CD8+, and regulatory T cells in addition to natural killer cells. Results: No adverse effects were detected in any of the treated groups. Survival analysis indicated that the groups receiving dual or triple therapies had prolonged survival compared to the controls. However, the group receiving triple therapy was the only group to show statistically significant increase in survival compared to the controls. Tumor size progression paralleled the survival outcome. The group receiving the triple therapy showed statistically significant smaller tumor sizes compared to all the other groups throughout the whole monitoring period. Flow cytometry used to analyze immune cell populations in the tumor mass indicated that the triple immune therapy was capable of significantly enhancing the natural killer cell counts as well as the CD3+CD4+/Treg and CD3+CD8+/Treg ratios possibly enhancing the anti-tumorigenic environment. Conclusions: Generated data rule out any major adverse events pertaining to the triple immunotherapy and reveal its enhanced effectiveness in thwarting melanoma progression over all other tested treatments.

Coenzyme A governs proinflammatory macrophage metabolism

“…Similar to other tumor models (12,42,43), intratumoral (i.t) MPLA alone had no effect on MMTV-PyMT orthotopic breast tumor growth (Fig. 3A left, Fig.…”

Tumor-Infiltrating CD8+ T Cells Driven by the Immune Checkpoint-Associated Gene IDO1 Are Associated With Cervical Cancer Prognosis

“…It decreases tryptophan(Trp) and produces a series of toxic kynurenine(Kyn) metabolites ( 43 ). The toxic Kyn metabolites directly suppress the effector T cell response by favoring differentiation of Tregs ( 44 , 45 ). The immune checkpoint is a key molecule in T-cell dysfunction.…”

“…Jallad et al. found that the triple immune therapy was capable of significantly enhancing the natural killer cell counts as well as the CD3 + CD4 + /T reg and CD3 + CD8 + /Treg ratios possibly enhancing the anti-tumorigenic environment ( 44 ). The present study also provides support for the application of IDO1 inhibitors in cervical cancer.…”

Harnessing NK cells for cancer immunotherapy: immune checkpoint receptors and chimeric antigen receptors

“…Thus, anti-CTLA-4 therapy may enhance antitumor cytotoxicity of NK cells in both a direct and indirect manner such as depletion of CTLA-4 + Treg cells. Triple immunotherapy with anti-CTLA4 antibodies, monophosphoryl-lipid-A, and indolamine-dioxygenase-1 inhibitor has been reported to enhance NK cell counts and the CD3 + CD4 + /Treg and CD3 + CD8 + /Treg ratios, in addition to the reduction in tumor mass, in a murine melanoma model ( 44 ). Combination therapies could provide additional benefits, although the B7/CTLA-4 axis may not play a key role in NK cell activation ( 45 , 46 ).…”