Despite the increased rate of complete response to initial chemotherapy, most patients with advanced ovarian cancer relapse and succumb to progressive disease. Dendritic cell (DC)-based immunotherapy has been developed as a novel strategy for generating antitumor immunity as part of cancer treatments. The present study aimed to assess the feasibility and clinical effects of DC therapy for recurrent ovarian cancer (ROC).

Despite significant recent advances in the development of immune checkpoint inhibitors, the treatment of advanced colorectal cancer involving metastasis to distant organs remains challenging. We conducted a phase I study to investigate the safety and immunogenicity of Wilms’ tumor (WT1) class I/II peptides-pulsed dendritic cell DC vaccination for patients with advanced colorectal cancer. Standard treatment comprising surgical resection and chemotherapy was followed by one course of seven biweekly administrations of 1–2 × 10⁷ DCs with 1–2 KE of OK-432 (streptococcal preparation) in three patients. Clinical efficacy was confirmed based on WT1 expression using immunohistochemistry on paraffin-embedded tissues and immune monitoring using tetramer analysis and enzyme-linked immunosorbent spot (ELISPOT) assays. WT1 expression with human leukocyte antigen (HLA)-class I molecules was detected in surgical resected tissues. Adverse reactions to DC vaccinations were tolerable under an adjuvant setting. WT1-specific cytotoxic T cells were detected by both modified WT1-peptide/HLA-A*24:02 tetramer analysis and/or interferon-γ-producing cells through the use of ELISPOT assays after the first DC vaccination. Immunity acquired from DC vaccination persisted for two years with prolonged disease-free and overall survival. The present study indicated that DC vaccination targeting WT1 demonstrated the safety and immunogenicity as an adjuvant therapy in patients with resectable advanced colorectal cancer.

Background We aimed to develop a chemoimmunotherapy regimen consisting of a novel Wilms’ tumor 1 (WT1) peptide-pulsed dendritic cell (WT1-DC) vaccine and multiagent chemotherapy and to investigate the safety, clinical outcomes, and WT1-specific immune responses of patients with unresectable advanced pancreatic ductal adenocarcinoma (UR-PDAC) who received this treatment. Methods Patients with UR-PDAC with stage III disease (locally advanced (LA-PDAC; n=6)), stage IV disease (metastatic (M-PDAC; n=3)), or recurrent disease after surgery (n=1) were enrolled in this phase I study. The patients received one cycle of nab-paclitaxel plus gemcitabine alone followed by 15 doses of the WT1-DC vaccine independent of chemotherapy. The novel WT1 peptide cocktail was composed of a multifunctional helper peptide specific for major histocompatibility complex class II, human leukocyte antigen (HLA)-A*02:01, or HLA-A*02:06 and a killer peptide specific for HLA-A*24:02. Results The chemoimmunotherapy regimen was well tolerated. In the nine patients for whom a prognostic analysis was feasible, the clinical outcomes of long-term WT1 peptide-specific delayed-type hypersensitivity (WT1-DTH)-positive patients (n=4) were significantly superior to those of short-term WT1-DTH-positive patients (n=5). During chemoimmunotherapy, eight patients were deemed eligible for conversion surgery and underwent R0 resection (four patients with LA-PDAC, one patient with M-PDAC, and one recurrence) or R1 resection (one patient with M-PDAC), and one patient with LA-PDAC was determined to be unresectable. Long-term WT1-DTH positivity was observed in three of the four patients with R0-resected LA-PDAC. These three patients exhibited notable infiltration of T cells and programmed cell death protein-1+ cells within the pancreatic tumor microenvironment (TME). All patients with long-term WT1-DTH positivity were alive for at least 4.5 years after starting therapy. In patients with long-term WT1-DTH positivity, the percentage of WT1-specific circulating CD4+ or CD8+ T cells that produced IFN-γ or TNF-α was significantly greater than that in patients with short-term WT1-DTH positivity after two vaccinations. Moreover, after 12 vaccinations, the percentages of both circulating regulatory T cells and myeloid-derived suppressor cells were significantly lower in patients with long-term WT1-DTH-positive PDAC than in short-term WT1-DTH-positive patients. Conclusions Potent activation of WT1-specific immune responses through a combination chemoimmunotherapy regimen including the WT1-DC vaccine in patients with UR-PDAC may modulate the TME and enable conversion surgery, resulting in clinical benefits (Online supplemental file 1). Trial registration number jRCTc030190195.

Given the recent advancements of immune checkpoint inhibitors, there is considerable interest in cancer immunotherapy provided through dendritic cell (DC)-based vaccination. Although many studies have been conducted to determine the potency of DC vaccines against cancer, the clinical outcomes are not yet optimal, and further improvement is necessary. In this study, we evaluated the potential ability of human platelet lysate (HPL) to produce interferon-α-induced DCs (IFN-DCs). In the presence of HPL, IFN-DCs (HPL-IFN-DCs) displayed high viability, yield, and purity. Furthermore, HPL-IFN-DCs displayed increased CD14, CD56, and CCR7 expressions compared with IFN-DCs produced without HPL; HPL-IFN-DCs induced an extremely higher number of antigen-specific cytotoxic T lymphocytes (CTLs) than IFN-DCs, which was evaluated with a human leukocyte antigen (HLA)-restricted melanoma antigen recognized by T cells 1 (MART-1) peptide. Additionally, the endocytic and proteolytic activities of HPL-IFN-DCs were increased. Cytokine production of interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α was also elevated in HPL-IFN-DCs, which may account for the enhanced CTL, endocytic, and proteolytic activities. Our findings suggest that ex-vivo-generated HPL-IFN-DCs are a novel monocyte-derived type of DC with high endocytic and proteolytic activities, thus highlighting a unique strategy for DC-based immunotherapies.