Immunotherapy Targeting HPV16/18 Generates Potent Immune Responses in HPV-Associated Head and Neck Cancer.

PURPOSE: Clinical responses with programmed death (PD-1) receptor-directed antibodies occur in about 20% of patients with advanced head and neck squamous cell cancer (HNSCCa). Viral neoantigens, such as the E6/E7 proteins of HPV16/18, are attractive targets for therapeutic immunization and offer an immune activation strategy that may be complementary to PD-1 inhibition. PATIENTS AND METHODS: We report phase Ib/II safety, tolerability, and immunogenicity results of immunotherapy with MEDI0457 (DNA immunotherapy targeting HPV16/18 E6/E7 with IL12 encoding plasmids) delivered by electroporation with CELLECTRA constant current device. Twenty-two patients with locally advanced, p16+ HNSCCa received MEDI0457. RESULTS: MEDI0457 was associated with mild injection site reactions, but no treatment-related grade 3-5 adverse events (AE) were noted. Eighteen of 21 evaluable patients showed elevated antigen-specific T-cell activity by IFNγ ELISpot, and persistent cellular responses surpassing 100 spot-forming units (SFUs)/106 peripheral blood mononuclear cells (PBMCs) were noted out to 1 year. Induction of HPV-specific CD8+ T cells was observed. MEDI0457 shifted the CD8+/FoxP3+ ratio in 4 of 5 post immunotherapy tumor samples and increased the number of perforin+ immune infiltrates in all 5 patients. One patient developed metastatic disease and was treated with anti-PD-1 therapy with a rapid and durable complete response. Flow-cytometric analyses revealed induction of HPV16-specific PD-1+ CD8+ T cells that were not found prior to MEDI0547 (0% vs. 1.8%). CONCLUSIONS: These data demonstrate that MEDI0457 can generate durable HPV16/18 antigen-specific peripheral and tumor immune responses. This approach may be used as a complementary strategy to PD-1/PD-L1 inhibition in HPV-associated HNSCCa to improve therapeutic outcomes.

CTLA-4/CD80 pathway regulates T cell infiltration into pancreatic cancer.

The ability of some tumors to exclude effector T cells represents a major challenge to immunotherapy. T cell exclusion is particularly evident in pancreatic ductal adenocarcinoma (PDAC), a disease where blockade of the immune checkpoint molecule CTLA-4 has not produced significant clinical activity. In PDAC, effector T cells are often scarce within tumor tissue and confined to peritumoral lymph nodes and lymphoid aggregates. We hypothesized that CTLA-4 blockade, despite a lack of clinical efficacy seen thus far in PDAC, might still alter T cell immunobiology, which would have therapeutic implications. Using clinically relevant genetic models of PDAC, we found that regulatory T cells (Tregs), which constitutively express CTLA-4, accumulate early during tumor development but are largely confined to peritumoral lymph nodes during disease progression. Tregs were observed to regulate CD4+, but not CD8+, T cell infiltration into tumors through a CTLA-4/CD80 dependent mechanism. Disrupting CTLA-4 interaction with CD80 was sufficient to induce CD4 T cell infiltration into tumors. These data have important implications for T cell immunotherapy in PDAC and demonstrate a novel role for CTLA-4/CD80 interactions in regulating T cell exclusion. In addition, our findings suggest distinct mechanisms govern CD4+ and CD8+ T cell infiltration in PDAC.

Exclusion of T Cells From Pancreatic Carcinomas in Mice Is Regulated by Ly6C(low) F4/80(+) Extratumoral Macrophages.

BACKGROUND & AIMS: Immunotherapies that induce T-cell responses have shown efficacy against some solid malignancies in patients and mice, but these have little effect on pancreatic ductal adenocarcinoma (PDAC). We investigated whether the ability of PDAC to evade T-cell responses induced by immunotherapies results from the low level of immunogenicity of tumor cells, the tumor's immunosuppressive mechanisms, or both. METHODS: Kras(G12D/+);Trp53(R172H/+);Pdx-1-Cre (KPC) mice, which develop spontaneous PDAC, or their littermates (controls) were given subcutaneous injections of a syngeneic KPC-derived PDAC cell line. Mice were then given gemcitabine and an agonist of CD40 to induce tumor-specific immunity mediated by T cells. Some mice were also given clodronate-encapsulated liposomes to deplete macrophages. Tumor growth was monitored. Tumor and spleen tissues were collected and analyzed by histology, flow cytometry, and immunohistochemistry. RESULTS: Gemcitabine in combination with a CD40 agonist induced T-cell-dependent regression of subcutaneous PDAC in KPC and control mice. In KPC mice given gemcitabine and a CD40 agonist, CD4(+) and CD8(+) T cells infiltrated subcutaneous tumors, but only CD4(+) T cells infiltrated spontaneous pancreatic tumors (not CD8(+) T cells). In mice depleted of Ly6C(low) F4/80(+) extratumoral macrophages, the combination of gemcitabine and a CD40 agonist stimulated infiltration of spontaneous tumors by CD8(+) T cells and induced tumor regression, mediated by CD8(+) T cells. CONCLUSIONS: Ly6C(low) F4/80(+) macrophages that reside outside of the tumor microenvironment regulate infiltration of T cells into PDAC and establish a site of immune privilege. Strategies to reverse the immune privilege of PDAC, which is regulated by extratumoral macrophages, might increase the efficacy of T-cell immunotherapy for patients with PDAC.

Notch directly regulates Gata3 expression during T helper 2 cell differentiation.

Notch signaling plays multiple roles to direct diverse decisions regarding cell fate during T cell development. During helper T (Th) cell differentiation, Notch is involved in generating optimal Th2 cell responses. Here, we present data investigating how Notch mediates Th2 cell differentiation. Notch showed a CD4(+) T cell intrinsic role in promoting IL-4 expression that required GATA-3. In the absence of Notch signals, Gata3 expression was markedly diminished. Introduction of an activated allele of Notch1 into CD4(+) T cells led to the specific and direct upregulation of a developmentally regulated Gata3 transcript that included the exon 1a sequences. Furthermore, Notch acted in parallel with GATA-3 to synergistically activate IL-4 expression. Together, these data implicate Gata3 as a direct transcriptional Notch target that acts in concert with Notch signaling to generate optimal Th2 cell responses.