Lymph Node–Targeted Immunotherapy Mediates Potent Immunity Resulting in Regression of Isolated or Metastatic Human Papillomavirus–Transformed Tumors

Abstract

Purpose: The goal of this study was to investigate the therapeutic potential of a novel immunotherapy strategy resulting in immunity to localized or metastatic human papillomavirus 16-transformed murine tumors. Experimental Design: Animals bearing E7-expressing tumors were coimmunized by lymph node injection with E7 49-57 antigen and TLR3-ligand (synthetic dsRNA). Immune responses were measured by flow cytometry and antitumor efficacy was evaluated by tumor size and survival. In situ cytotoxicity assays and identification of tumorinfiltrating lymphocytes and T regulatory cells were used to assess the mechanisms of treatment resistance in bulky disease. Chemotherapy with cyclophosphamide was explored to augment immunotherapy in late-stage disease. Results: In therapeutic and prophylactic settings, immunization resulted in a considerable expansion of E7 49-57 antigen-specific T lymphocytes in the range of 1/10 CD8 + T cells. The resulting immunity was effective in suppressing disease progression and mortality in a pulmonary metastatic disease model. Therapeutic immunization resulted in control of isolated tumors up to a certain volume, and correlated with antitumor immune responses measured in blood. In situ analysis showed that within bulky tumors, T-cell function was affected by negative regulatory mechanisms linked to an increase in T regulatory cells and could be overcome by cyclophosphamide treatment in conjunction with immunization. Conclusions: This study highlights a novel cancer immunotherapy platform with potential for translatability to the clinic and suggests its potential usefulness for controlling metastatic disease, solid tumors of limited size, or larger tumors when combined with cytotoxic agents that reduce the number of tumor-infiltrating T regulatory cells. (Clin Cancer Res 2009;15(19):6167-76) Human papillomavirus (HPV)-associated tumors remain a significant health care problem worldwide, as the second leading cause of cancer mortality in women (1, 2), and the number one cause of cancer-related death in women in developing countries (3, 4). Although effective prophylactic HPV vaccines have recently been developed targeting the late (L1 and L2) genes (5), they are ineffective at eliminating preexisting infection or HPV-related tumors whose cellular transformation and progression depend upon expression of the E6 and E7 early proteins (2). Therefore, a therapeutic vaccine triggering T-cell immunity specific to the E6 and E7 early proteins of HPV 16 and 18 strains-those responsible for the pathogenesis of the majority of cervical cancers (6)-could offer a promising option to prevent the progression of HPV infection to cervical cancer, or the progression of early stage tumors to invasive disease (2, 7).Recent advances in lymph node-targeted active immunotherapy, in our hands and others, have resulted in greatly improved CD8 + T-cell responses against a variety of tumor antigens (8-10). Using a novel intralymphatic immunization approach consisting of the administration of a HPV 16 tumor-...

Enhancing Efficacy of Anticancer Vaccines by Targeted Delivery to Tumor-Draining Lymph Nodes

“…4B) induced by targeting the vaccine to the tdLN led to regression of early-stage tumors and more impressively of tumors having reached the Swiss legal limit of 1 cm 3 . In the literature, cancer vaccines are usually administered when the tumors are 5 to 7 mm in diameter or even before they are detectable, and also do not usually induce this high number of TAA-specific CD8 þ T cells in the blood and the LNs (17,19,30,38,44), thus emphasizing the benefits of nanoparticle-mediated targeting of antigen and adjuvant to DCs in the tdLN (18,38,45). We noted, however, that after regressing some tumors grew back.…”

Multivalent immunity targeting tumor-associated antigens by intra-lymph node DNA-prime, peptide-boost vaccination

“…27 In addition, substantial immune responses achieved through intra-lymph node immunization with peptide and a TLR agonist were a prerequisite for effective control of tumor progression in immune-competent mice. 30 Therefore, we hypothesized that intra-lymph node DNA vaccination is an optimal priming strategy with the caveat that it is still not known whether a preferential induction of a specialized T-cell subset or simply a large expansion of TAA-specific T cells is crucial for the effectiveness of this category of vaccine. In addition, it has been reported that TLR agonists can activate TLR signaling and B7-H1 (PD-L1) expression on tumor cells resulting in T-cell suppression, 31,32 although systemic exposure to TLR agonists is expected to be limited after intra-lymph node injection (data not shown).…”

Implications of Human Papillomavirus Infections in the Biology of Head and Neck Cancers

“…One hypothesis suggested by the authors is that HPV-16-positive tumors have increased antigenicity through the E7 antigen, causing enhanced stimulation of the immune system, which more readily identifies tumor cells as foreign. This hypothesis is supported by a study led by Smith et al, in which the intralymphatic immunization of mice bearing E7-expressing tumors with E7 peptide resulted in a considerable expansion of E7-specific CD8 cells, which are effective in suppressing disease progression (Smith et al, 2009). In another animal model, the DNA vaccine with HSP70 fused to HPV-16 E7 has been demonstrated to dramatically increase the frequency of E7-specific CD8-positive T cells and to enhance the antitumor effects against E7-expressing tumor cells (Chen et al, 2000).…”