Hiroki Shomura

Humoral Responses to Peptides Correlate with Overall Survival in Advanced Cancer Patients Vaccinated with Peptides Based on Pre-existing, Peptide-Specific Cellular Responses

Purpose: The aim of this study is to find a laboratory marker for overall survival in advanced cancer patients who were vaccinated with peptides based on pre-existing, peptide-specific CTL precursors in the circulation. Experimental Design: A group of 113 patients with advanced cancer (28 colorectal, 22 prostate, 15 lung, 14 gastric, and 34 other cancers) was enrolled in a Phase I clinical study of peptide vaccination in which peptide-specific CTL precursors of prevaccination peripheral blood mononuclear cells were measured, followed by vaccination with these peptides (maximum of four). For cellular responses, pre and postvaccination (sixth) peripheral blood mononuclear cells were provided for measurement of both peptide-specific CTL precursors by IFN-γ release assay and tumor reactivity by 51Cr release assay. Delayed type hypersensitivity was also measured. For humoral response, pre and postvaccination (sixth) sera were provided for measurement of peptide-reactive IgG by an ELISA. Results: The median survival time and 1-year survival rate of the total cases were 346 ± 64.9 days and 44.6%, respectively, and those of patients vaccinated more than six times (n = 91) were 409 ± 15 days and 54.4%, respectively. In these 91 patients, the overall survival of patients whose sera showed increased levels of peptide-reactive IgG (n = 60) was significantly more prolonged (P = 0.0003) than that of patients whose sera did not (n = 31), whereas none of cellular responses correlated with overall survival. Conclusions: Peptide-specific IgG in postvaccination sera could be a suitable laboratory maker for the prediction of prolonged survival in advanced cancer patients vaccinated with peptides based on pre-existing CTL precursors.

Immunological evaluation of peptide vaccination for patients with gastric cancer based on pre‐existing cellular response to peptide

There is no standard treatment modality for advanced gastric cancer (GC) at the present time. To develop a new treatment modality, we investigated the immunological responses of advanced GC patients (n=13, 9 non‐scirrhous and 4 scirrhous types) vaccinated with peptides to a regimen under which pre‐vaccination peripheral blood mononuclear cells (PBMCs) were screened for their reactivity in vitro to each of 14 peptides on HLA‐A24 or 16 peptides on ‐A2 allele, then only the reactive peptides (maximum: 4) were administered in vivo. This regimen was generally well tolerated, although grade I levels of fever and local skin reactions were observed in several patients. Delayed‐type hypersensitivity (DTH) to the vaccinated peptides was observed in 4 patients. Increased cellular and humoral immune responses to the vaccinated peptides were observed in post‐vaccination PBMCs from 4 of 8 patients and in post‐vaccination sera of 8 of 10 patients tested, respectively. Prolonged survival was observed in patients showing cellular and humoral immune responses to the vaccinated peptides in the post‐vaccination samples, including all 4 patients with the scirrhous type. These results encourage further development of peptide‐based immunotherapy for GC patients.

A phase I trial of cytotoxic T-lymphocyte precursor-oriented peptide vaccines for colorectal carcinoma patients.

In most protocols of peptide-based vaccination, no consideration has been paid to whether or not peptide-specific cytotoxic T-lymphocyte (CTL) precursors are pre-existent in cancer patients. Initiation of immune boosting through vaccination is better than that of immune priming to induce prompt and strong immunity. In this study, 10 human histocompatibility leukocyte antigen-A24+ patients with advanced colorectal carcinomas were treated with up to four peptides that had been positive for pre-vaccination measurement of peptide-specific CTL precursors in the circulation (CTL precursor-oriented peptide vaccine). No severe adverse effect was observed, although local pain and fever of grade I or II were observed. Post-vaccination peripheral blood mononuclear cells (PBMCs) from five patients demonstrated an increased peptide-specific immune response to the peptides. Increased CTL response to cancer cells was detected in post-vaccination PBMCs of five patients. Antipeptide immunoglobulin G became detectable in post-vaccination sera of seven patients. Three patients developed a positive delayed-type hypersensitivity response to at least one of the peptides administrated. One patient was found to have a partial response; another had a stable disease, sustained through 6 months. These results encourage further development of CTL precursor-oriented vaccine for colorectal cancer patients.

Ran, a Small GTPase Gene, Encodes Cytotoxic T Lymphocyte (CTL) Epitopes Capable of Inducing HLA-A33–restricted and Tumor-Reactive CTLs in Cancer Patients

Purpose: The purpose is to identify a gene coding for tumor-associated antigen and peptide capable of inducing CTLs reactive to tumor cells with a HLA-A33–restricted fashion to provide scientific basis for specific immunotherapy to HLA-A33+ cancer patients. Experimental Design: An expression gene-cloning method was used to identify the tumor-associated antigen gene. Northern blot analysis and immunohistochemistry were used to examine the mRNA and protein expression levels in various cells and tissues, respectively. Synthetic peptides were examined for their ability to induce HLA-A33+ tumor-reactive CTLs in peripheral blood mononuclear cells from cancer patients. Result: A gene of small GTPase, Ran, which controls the cell cycle through the regulation of nucleocytoplasmic transport, mitotic spindle organization, and nuclear envelope formation, was found to encode epitopes recognized by the HLA-A33–restricted CTLs established from T cells infiltrating into gastric adenocarcinoma. The expression of the Ran gene was increased in most cancer cell lines and cancer tissues at both the mRNA and protein levels. However, it was not enhanced in the surrounding normal cells or tissues. It was also undetectable in normal tissues as far as tested. Ran-derived peptides at positions 48–56 and 87–95 could induce CD8+ peptide-specific CTLs reactive to tumor cells from HLA-A33+ epithelial cancer patients in a HLA class I-restricted manner. Conclusions: Because of its increased expression in cancer cells and involvement in malignant transformation and/or the enhanced proliferation of cancer cells, the two Ran-directed peptides could be potent candidates in use for specific immunotherapy against HLA-A33+ epithelial cancers.

Immunological evaluation of personalized peptide vaccination in combination with a 5-fluorouracil derivative (TS-1) for advanced gastric or colorectal carcinoma patients

The aim of the present study was to investigate the safety and immunological responses of personalized peptide vaccination in combination with oral administration of a 5‐fluorouracil derivative (TS‐1) in advanced gastric or colorectal carcinoma patients. Eleven patients (four with gastric cancer and seven with colorectal cancer) who failed to improve by prior TS‐1‐based chemotherapies were enrolled in this study. Peptides to be administered to patients were determined based on the presence of peptide‐specific cytotoxic T lymphocyte (CTL) precursors in peripheral blood mononuclear cells and peptide‐specific IgG in the plasma of cancer patients. Patients were vaccinated with peptides (a maximum of four) biweekly in combination with or without three different doses of TS‐1 (20, 40 and 80 mg/m2/day). Although grade 3 toxicity, including anemia (one patient) and neutropenia (one patient) were observed, the combination therapy was generally well tolerated. An increase in peptide‐specific IgG after the sixth vaccination was observed in the vast majority of patients irrespective of the dose of TS‐1 used. In contrast, an increase in peptide‐specific interferon‐γ production by CTL was most evident in patients who were administered the highest dose of TS‐1. Furthermore, in the patients who received 80 mg/m2/day TS‐1, CTL‐mediated cytotoxicity against cancer cells was maintained at the prevaccination level. These results indicate that administration of the standard dose (80 mg/m2/day) of TS‐1 in combination with a personalized peptide vaccination does not necessarily impede immunological responses in cancer patients, and could actually maintain or augment them. (Cancer Sci 2007; 98: 1113–1119)

Identification of parathyroid hormone-related protein-derived peptides immunogenic in human histocompatibility leukocyte antigen-A24+ prostate cancer patients.

Parathyroid hormone-related protein (PTHrP) is a key factor in the development of bone metastases, which are a major barrier in treating prostate cancer patients. In this study, we attempted to identify PTHrP-derived peptides immunogenic in human histocompatibility leukocyte antigen (HLA)-A24+ prostate cancer patients. Among four different PTHrP peptides carrying the HLA-A24 binding motif, both the PTHrP36–44 and PTHrP102–111 peptides efficiently induced peptide-specific cytotoxic T lymphocytes from peripheral blood mononuclear cells (PBMCs) of HLA-A24+ prostate cancer patients. Peptide-stimulated PBMCs showed cytotoxicity against prostate cancer cells in an HLA-A24-restricted manner. Experiments using antibodies and cold inhibition targets confirmed that their cytotoxicity was dependent on PTHrP peptide-specific and CD8+ T cells. Immunoglobulin G reactive to the PTHrP102–111 or PTHrP110–119 peptide was frequently detected in the plasma of prostate cancer patients, suggesting that the PTHrP102–111 peptide is able to elicit cellular and humoral immune responses in cancer patients. These results indicate that the PTHrP could be a promising target molecule for specific immunotherapy of HLA-A24+ prostate cancer patients with metastases.

Identification of HER2/neu-Derived Peptides Capable of Inducing both Cellular and Humoral Immune Responses in HLA-A24 Positive Breast Cancer Patients

HRE2/neu-specific cellular and humoral immune responses are often detected in breast cancer patients, but identification of more immunogenic CTL epitope peptides is necessary prior to development of a cancer vaccine. There is accumulating evidence of strong immunogenicity of peptides capable of inducing both cellular and humoral immune responses. To identify such peptides, this study intended to determine HER2/neu-derived peptides capable of inducing both cellular and humoral immunity in HLA-A24+ breast cancer patients. IgGs reactive to the HER2342–350, HER2485–493, and HER2553–561 peptides were detected in the sera of these patients with the frequency of 47, 24, and 24%, respectively. These peptides also induced peptide-specific and tumor-reactive CTL activity in the peripheral blood mononuclear cells of HLA-A24+ breast cancer patients with the frequency of 50, 63, and 25%, respectively, but such activity was not induced from any HLA-A24− patients. Cellular and humoral responses to each of these three peptides were also observed in PBMCs and sera from the other epithelial cancer patients. These results may provide a scientific basis for new clinical trials of HER2/neu-peptide-based immunotherapy for breast cancer and also other epithelial cancer patients.

Total pancreatectomy for metachronous mixed acinar-ductal carcinoma in a remnant pancreas

In October 2009, a 71-year-old female was diagnosed with a cystic tumor in the tail of the pancreas with an irregular dilatation of the main pancreatic duct in the body and tail of the pancreas. A distal pancreatectomy with splenectomy, and partial resection of the duodenum, jejunum and transverse colon was performed. In March 2011, a follow-up computed tomography scan showed a low density mass at the head of the remnant pancreas. We diagnosed it as a recurrence of the tumor and performed a total pancreatectomy for the remnant pancreas. In the histological evaluation of the resected specimen of the distal pancreas, the neoplastic cells formed an acinar and papillary structure that extended into the main pancreatic duct. Mucin5AC, α1-antitrypsin (α-AT) and carcinoembryonic antigen (CEA) were detected in the tumor cells by immunohistochemistry. In the resected head of the pancreas, the tumor was composed of both acinar and ductal elements with a mottled pattern. The proportions of each element were approximately 40% and 60%, respectively. Strongly positive α-AT cells were detected in the acinar element. Some tumor cells were also CEA positive. However, the staining for synaptophysin and chromogranin A was negative in the tumor cells. Ultimately, we diagnosed the tumor as a recurrence of mixed acinar-ductal carcinoma in the remnant pancreas. In conclusion, we report here a rare case of repeated pancreatic resection for multicentric lesions of mixed acinar-ductal carcinoma of the pancreas.

Clear cell sarcoma of the esophagus: report of a case

We report a rare case of clear cell sarcoma of the esophagus and review the literature regarding clear cell sarcomas of the gastrointestinal tract. A 57-year-old male was admitted with dysphagia during swallowing. Preoperative imaging studies, including upper gastrointestinal endoscopy and endoscopic ultrasonography, showed that the tumor was located between the mucosa and the muscularis propria of the lower esophagus. We performed subtotal esophagectomy with gastric tube reconstruction. Pathological findings of the tumor showed mixed spindle cells and oval cells. Immunohistochemical staining showed that the tumor cells were positive for S-100, vimentin and neuron-specific enolase and negative for α-smooth muscle actin, myoglobin and c-kit. Fluorescence in situ hybridization using a Ewing sarcoma breakpoint region 1 probe showed split signals in a small percentage of cells. We finally diagnosed the patient with clear cell sarcoma of the esophagus.

Pancreatoduodenectomy for circumportal pancreas accompanying the retroportal pancreatic duct: a case report and review of the literature

Circumportal pancreas (CP) is an extremely rare pancreatic fusion anomaly which is usually asymptomatic. This report presents the case of a patient with a tumor in the head of a CP and the retroportal accessory pancreatic duct in the pancreatic tissue behind the portal vein. A 53-year-old male was diagnosed with a nonfunctioning neuroendocrine tumor of the pancreas and resection of the tumor was scheduled. The patient was revealed to have CP on preoperative computed tomography and endoscopic retrograde cholangiopancreatography, which showed the pancreatic tissue encircling the portal vein and the retroportal accessory pancreatic duct. The patient safely underwent pylorus-preserving pancreatoduodenectomy reconstructed with pancreaticogastrostomy.