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In-situ tumor vaccination: Bringing the fight to the tumor.

ABSTRACT: After decades of development in the shadow of traditional cancer treatment, immunotherapy has come into the spotlight. Treatment of metastatic tumors with monoclonal antibodies to T cell checkpoints like programed cell death 1 (PD-1) or its ligand, (PD-L1), have resulted in significant clinical responses across multiple tumor types. However, these therapies fail in the majority of patients with solid tumors, in particular those who lack PD1(+)CD8(+) tumor-infiltrating lymphocytes within their tumors. Intratumoral "in situ vaccination" approaches seek to enhance immunogenicity, generate tumor infiltrating lymophcytes (TIL) and drive a systemic anti-tumor immune response, directed against "unvaccinated," disseminated tumors. Given the emerging picture of intratumoral immunotherapy as safe and capable of delivering systemic efficacy, it is anticipated that these approaches will become integrated into future multi-modality therapy.

SUBMITTER: Pierce RH

PROVIDER: S-EPMC4635874 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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In-situ tumor vaccination: Bringing the fight to the tumor.

Pierce Robert H RH Campbell Jean S JS Pai Sara I SI Brody Joshua D JD Kohrt Holbrook E K HE

Human vaccines & immunotherapeutics 20150101 8

After decades of development in the shadow of traditional cancer treatment, immunotherapy has come into the spotlight. Treatment of metastatic tumors with monoclonal antibodies to T cell checkpoints like programed cell death 1 (PD-1) or its ligand, (PD-L1), have resulted in significant clinical responses across multiple tumor types. However, these therapies fail in the majority of patients with solid tumors, in particular those who lack PD1(+)CD8(+) tumor-infiltrating lymphocytes within their tu ...[more]

PMID: 26055074

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Project description:In situ vaccination is an emerging cancer treatment strategy that uses local therapies to stimulate a systemic antitumor immune response. We previously reported an in situ vaccination effect when combining radiation (RT) with intratumor (IT) injection of tumor-specific immunocytokine (IC), a fusion of tumor-specific antibody and IL2 cytokine. In mice bearing two tumors, we initially hypothesized that delivering RT plus IT-IC to the "primary" tumor would induce a systemic antitumor response causing regression of the "secondary" tumor. To test this, mice bearing one or two syngeneic murine tumors of B78 melanoma and/or Panc02 pancreatic cancer were treated with combined external beam RT and IT-IC to the designated "primary" tumor only. Primary and secondary tumor response as well as animal survival were monitored. Immunohistochemistry and quantitative real-time PCR were used to quantify tumor infiltration with regulatory T cells (Treg). Transgenic "DEREG" mice or IgG2a anti-CTLA-4 were used to transiently deplete tumor Tregs. Contrary to our initial hypothesis, we observed that the presence of an untreated secondary tumor antagonized the therapeutic effect of RT + IT-IC delivered to the primary tumor. We observed reciprocal tumor specificity for this effect, which was circumvented if all tumors received RT or by transient depletion of Tregs. Primary tumor treatment with RT + IT-IC together with systemic administration of Treg-depleting anti-CTLA-4 resulted in a renewed in situ vaccination effect. Our findings show that untreated tumors can exert a tumor-specific, Treg-dependent, suppressive effect on the efficacy of in situ vaccination and demonstrate clinically viable approaches to overcome this effect. Untreated tumor sites antagonize the systemic and local antitumor immune response to an in situ vaccination regimen. This effect is radiation sensitive and may be mediated by tumor-specific regulatory T cells harbored in the untreated tumor sites. Cancer Immunol Res; 6(7); 825-34. ©2018 AACR.

Project description:BACKGROUND:Immune checkpoint inhibition (ICI) alone is not efficacious for a large number of patients with melanoma brain metastases. We previously established an in situ vaccination (ISV) regimen combining radiation and immunocytokine to enhance response to ICIs. Here, we tested whether ISV inhibits the development of brain metastases in a murine melanoma model. METHODS:B78 (GD2+) melanoma 'primary' tumors were engrafted on the right flank of C57BL/6 mice. After 3-4 weeks, primary tumors were treated with ISV (radiation (12?Gy, day 1), ?-GD2 immunocytokine (hu14.18-IL2, days 6-10)) and ICI (?-CTLA-4, days 3, 6, 9). Complete response (CR) was defined as no residual tumor observed at treatment day 90. Mice with CR were tested for immune memory by re-engraftment with B78 in the left flank and then the brain. To test ISV efficacy against metastases, tumors were also engrafted in the left flank and brain of previously untreated mice. Tumors were analyzed by quantitative reverse transcription-PCR, immunohistochemistry, flow cytometry and multiplex cytokine assay. RESULTS:ISV+?-CTLA-4 resulted in immune memory and rejection of B78 engraftment in the brain in 11 of 12 mice. When B78 was engrafted in brain prior to treatment, ISV+?-CTLA-4 increased survival compared with ICI alone. ISV+?-CTLA-4 eradicated left flank tumors but did not elicit CR at brain sites when tumor cells were engrafted in brain prior to ISV. ISV+?-CTLA-4 increased CD8+ and CD4+ T cells in flank and brain tumors compared with untreated mice. Among ISV + ?-CTLA-4 treated mice, left flank tumors showed increased CD8+ infiltration and CD8+:FOXP3+ ratio compared with brain tumors. Flank and brain tumors showed minimal differences in expression of immune checkpoint receptors/ligands or Mhc-1. Cytokine productions were similar in left flank and brain tumors in untreated mice. Following ISV+?-CTLA-4, production of immune-stimulatory cytokines was greater in left flank compared with brain tumor grafts. CONCLUSION:ISV augmented response to ICIs in murine melanoma at brain and extracranial tumor sites. Although baseline tumor-immune microenvironments were similar at brain and extracranial tumor sites, response to ISV+?-CTLA-4 was divergent with reduced infiltration and activation of immune cells in brain tumors. Additional therapies may be needed for effective antitumor immune response against melanoma brain metastases.

Project description:PurposeRecent studies have shown that a new generation of synthetic agonist of Toll-like receptor (TLR) 9 consisting a 3'-3'-attached structure and a dCp7-deaza-dG dinucultodie shows more potent immunostimulatory effects in both mouse and human than conventional CpG oligonucleotides. Radiation therapy (RT) provides a source of tumor antigens that are released from dying, irradiated, tumor cells without causing systemic immunosuppression. We, therefore, examined effect of combining RT with a designer synthetic agonist of TLR9 on anti-tumoral immunity, primary tumor growth retardation and metastases in a murine model of lung cancer.MethodsGrouped C57BL/6 and congenic B cell deficient mice (B(-/-)) bearing footpad 3LL tumors were treated with PBS, TLR9 agonist, control oligonucelotide, RT or the combination of RT and TLR9 agonist. Immune phenotype of splenocytes and serum IFN-? and IL-10 levels were analyzed by FACS and ELISA, 24 h after treatment. Tumor growth, lung metastases and survival rate were monitored and tumor specific antibodies in serum and deposition in tumor tissue were measured by ELISA and immunofluorescence.ResultsTLR9 agonist expanded and activated B cells and plasmacytoid dendritic cells in wild-type mice and natural killer DCs (NKDCs) in B cell-deficient (B(-/-)) mice bearing ectopic Lewis lung adenocarcinoma (3LL). Combined RT with TLR9 agonist treatment inhibited 3LL tumor growth in both wild type and B(-/-) mice. A strong tumor-specific humoral immune response (titer: 1/3200) with deposition of mouse IgG auto-antibodies in tumor tissue were found in wildtype mice, whereas the number of tumor infiltrating NKDCs increased in B(-/-) mice following RT+ TLR9 agonist therapy. Furthermore, mice receiving combination therapy had fewer lung metastases and a higher survival than single treatment cohorts.ConclusionsCombination therapy with TLR9 agonist and RT induces systemic anti-tumoral humoral response, augments tumoral infiltration of NKDCs, reduces pulmonary metastases and improves survival in a murine model of 3LL cancer.

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In-situ tumor vaccination: Bringing the fight to the tumor.

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In-situ tumor vaccination: Bringing the fight to the tumor.

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