Integrity of circulating cell-free DNA as a prognostic biomarker for vaccine therapy in patients with nonsmall cell lung cancer.

BACKGROUND: Many clinical trials of immune checkpoint blockade-based combination therapies are under way. Vaccine therapy is a promising partner of combination therapies. We have developed a personalized peptide vaccination and conducted clinical trials of it in patients with various cancers. At the present time, we have only a limited number of biomarkers related to the prognosis of vaccine-treated patients. Thus, new biomarkers are urgently needed. METHODS: In this study, we investigated the plasma cell-free DNA (cfDNA) integrity-a ratio of the necrotic tumor cell-derived long cfDNA fragments to the total dead cell-derived short cfDNA fragments from genomic Alu elements-in patients with advanced nonsmall cell lung cancer during treatment with the personalized peptide vaccination. RESULTS: We found that (1) the cfDNA integrity was decreased after the first cycle of vaccination, and (2) the patients with high prevaccination cfDNA integrity survived longer than those with low prevaccination integrity (median survival time (MST): 17.9 versus 9.0 months, respectively; hazard ratio (HR): 0.58, p = .0049). A similar tendency was observed in postvaccination cfDNA integrity (MST: 16.4 vs 9.4 months; HR: 0.65, p = .024). CONCLUSIONS: These results suggest that cfDNA integrity is a possible prognostic biomarker in patients treated with the personalized peptide vaccine.

CD4/CD8 ratio is a prognostic factor in IgG nonresponders among peptide vaccine-treated ovarian cancer patients.

The identification of useful biomarkers is an urgent issue in cancer treatment, particularly for immunotherapy, as only some patients experience benefits from this treatment. The early induction of the IgG response has been reported as a useful biomarker of favorable prognosis for cancer patients treated with a personalized peptide vaccination, but a portion of these patients (IgG nonresponders) fail to achieve an early induction of IgG response yet experience long-term survival. It is thus necessary to identify other biomarkers of favorable prognosis among these patients. Here we report the usefulness of classical T-cell markers (ie, the CD8 content and the CD4/CD8 ratio in peripheral blood) in IgG nonresponders among advanced or recurrent ovarian cancer patients treated with a personalized peptide vaccination. Among IgG nonresponders (n = 25), the overall survival (OS) of the increased-CD8 group (n = 7) was significantly longer than that of the decreased-CD8 group (n = 18; P = .018), and the OS of the patients with a decreased CD4/CD8 ratio (n = 10) was significantly longer than that of the patients with an increased ratio (n = 15; P = .0055). Thus, an increased content of CD8 and a decreased CD4/CD8 ratio are each favorable prognosis markers in IgG nonresponders treated with a personalized peptide vaccination.

Integrity of plasma DNA is inversely correlated with vaccine-induced antitumor immunity in ovarian cancer patients.

Cancer immunotherapy including vaccine therapy is a promising modality for cancer treatment, but few patients show its clinical benefits currently. The identification of biomarkers that can identify patients who will benefit from cancer immunotherapy is thus important. Here, we investigated the potential utility of the circulating cell-free DNA (cfDNA) integrity-a ratio of necrotic cell-derived, longer DNA fragments versus apoptotic cell-derived shorter fragments of Alu gene-as a biomarker of vaccine therapy for patients with ovarian cancer. We analyzed plasma samples from 39 patients with advanced or recurrent ovarian cancer enrolled in clinical trials for personalized peptide vaccinations. We observed that (1) the cfDNA integrity was decreased after the first cycle of vaccination, and (2) the decreased levels of cfDNA integrity were correlated with vaccine-induced immune responses; i.e., decreased cfDNA integrity was observed in 91.7% and 59.3% of the IgG-positive and negative patients, respectively (p = 0.0445). Similarly, decreased cfDNA integrity was observed in 92.9% and 56.0% of CTL response-positive and negative patients, respectively (p = 0.0283). These results suggest that the circulating cfDNA integrity is a possible biomarker for cancer vaccine therapy.

Phase I study of a new cancer vaccine of ten mixed peptides for advanced cancer patients.

A phase I study of a new cancer vaccine (KRM-10), consisting of a mixture of 10 different short peptides, was conducted for patients with advanced gastrointestinal cancers. Primary or secondary endpoints included the dose-limiting toxicity (DLT), or safety and immune responses, respectively. Peptide-specific cytotoxic T lymphocytes (CTL) and immunoglobulin G (IgG), together with soluble inflammatory factors, were measured before and after vaccination. Twenty-one patients were vaccinated with KRM-10 at dose levels of 10 (n = 6), 20 (n = 8) or 30 mg (n = 7) of peptides every week for 6 weeks. No DLT were observed in the dose range evaluated. Common treatment-related adverse events were a grade 1 injection site reaction in 15 patients, and fever in three patients (grade 1 in two patients and grade 2 in one patient). CTL activity to at least one peptide at the time of the third and sixth vaccination increased in 2 and 3 of 6 (10 mg), 2 of 8 and 4 of 6 (20 mg), or 2 and 1 of 6 (30 mg) patients, respectively. IgG levels, at the third and sixth vaccination, were also increased in 1 and 1 of 6 (10 mg), 2 of 8 and 4 of 6 (20 mg), or 1 and 3 of 6 (30 mg) patients, respectively. The KRM-10 vaccine consisting of 20 mg of peptides was determined as the optimal dose for a coming phase II trial because of its safety, and also for demonstrating the most potent activity for augmenting the immune response of the three doses tested. This trial was registered at the UMIN Clinical Trials Registry as UMIN000008820.

Haptoglobin promoter polymorphism rs5472 as a prognostic biomarker for peptide vaccine efficacy in castration-resistant prostate cancer patients.

Personalized peptide vaccination (PPV) is an attractive approach to cancer immunotherapy with strong immune-boosting effects conferring significant clinical benefit. However, as with most therapeutic agents, there is a difference in clinical efficacy among patients receiving PPV. Therefore, a useful biomarker is urgently needed for prognosticating clinical outcomes to preselect patients who would benefit the most from PPV. In this retrospective study, to detect a molecular prognosticator of clinical outcomes for PPV, we analyzed whole-genome gene expression profiles of peripheral blood mononuclear cells (PBMCs) in castration-resistant prostate cancer (CRPC) patients before administration of PPV. Cox regression analysis revealed that mRNA expression of myeloperoxidase, haptoglobin, and neutrophil elastase was significantly associated with overall survival (OS) among vaccinated CRPC patients (adjusted P < 0.01). By promoter sequence analysis of these three genes, we found that rs5472 of haptoglobin (HP), an acute-phase plasma glycoprotein, was strongly correlated to OS of vaccinated CRPC patients (P = 0.0047, hazard ratio 0.47; 95 % confidence interval 0.28-0.80). Furthermore, both HP mRNA expression in PBMCs and protein level in plasma of CRPC patients before administration of PPV exhibited rs5472 dependence (P < 0.001 for mRNA expression and P < 0.05 for protein level). Our findings suggest that rs5472 may play an important role in the immune response to PPV via regulation of HP. Thus, we concluded that rs5472 is a potential prognostic biomarker for PPV.

Phase I trial of a cancer vaccine consisting of 20 mixed peptides in patients with castration-resistant prostate cancer: dose-related immune boosting and suppression.

The heterogeneity expression of tumor-associated antigens (TAA) and variability of human T cell repertoire suggest that effective cancer vaccine requires induction of a wide breadth of cytotoxic T lymphocyte (CTL) specificities. This can be achieved with vaccines targeting multiple TAA. We evaluated the safety and immune dynamics of a cancer vaccine consisting of 20 mixed peptides (KRM-20) designed to induce CTLs against 12 different TAA in patients with castration-resistant prostate cancer (CRPC). Patients received each of three different randomly assigned doses of KRM-20 (6, 20, or 60 mg) once a week for 6 weeks. KRM-20 was applicable for patients with positive human leukocyte antigen (HLA) A2, A3, A11, A24, A26, A31 or A33 alleles, which cover the majority of the global population. To evaluate the minimum immunological effective dose (MIED), peptide-specific CTL and immunoglobulin G (IgG) responses, and immune suppressive subsets were evaluated during the vaccination. Total of 17 patients was enrolled. No serious adverse drug reactions were encountered. The MIED of KRM-20 in CTL or IgG response calculated by logistic regression model was set as 16 or 1.6 mg, respectively. The frequency of immune suppressive subsets was fewer in the 20 mg cohort than that in 6 or 60 mg cohort. Clinical responses determined by prostate-specific antigen levels were two partial responses (from the 20 mg cohort), five no changes and ten progressive diseases. Twenty milligrams of KRM-20 could be recommended for further studies because of the safety and ability to augment CTL activity.

PD-1 expression on peripheral blood T-cell subsets correlates with prognosis in non-small cell lung cancer.

PD-1 expression in peripheral blood T-cells has been reported in several kinds of cancers, including lung cancer. However, the relationship between PD-1 expression in peripheral blood T-cells and prognosis after treatment with a cancer vaccine has not been reported. To elucidate this relationship, we analyzed PD-1 expression in the peripheral blood T-cells of patients with non-small cell lung cancer. The blood samples used in this study were obtained from patients enrolled in phase II clinical trials of a personalized peptide vaccine. Seventy-eight samples obtained before and after a single vaccination cycle (consisting of six or eight doses) were subjected to the analysis. PD-1 was expressed on lymphocytes in the majority of samples. The relative contents of PD1(+) CD4(+) T-cells against total lymphocytes before and after the vaccination cycle correlated with overall survival (OS) with a high degree of statistical significance (P < 0.0001 and P = 0.0014). A decrease in PD-1(+) CD8(+) T-cells after one cycle of vaccination also correlated with longer OS (P = 0.032). The IgG response to the non-vaccinated peptides suggested that the epitope spreading seemed to occur more frequently in high-PD-1(+) CD4(+) T-cell groups. Enrichment of CD45RA(-) CCR7(-) effector-memory phenotype cells in PD-1(+) T-cells in PBMCs was also shown. These results suggest that PD-1 expression on the peripheral blood T-cell subsets can become a new prognostic marker in non-small cell lung cancer patients treated with personalized peptide vaccination.

Haptoglobin proved a prognostic biomarker in peripheral blood of patients with personalized peptide vaccinations for advanced castration-resistant prostate cancer.

Haptoglobin (Hp) is a well-known acute-phase protein that possibly has influence on tumors through the immune response. This study was conducted to evaluate the correlation between Hp expression and the effect of treatment by cancer peptide vaccines in advanced castration-resistant prostate cancer (CRPC) patients. Hp expression was measured by RT-PCR using peripheral blood mononuclear cells (PBMCs) collected from advanced CRPC patients, who were divided into two groups: long-term survivors and short-term survivors. Before cancer peptide vaccination (pre-vaccination), Hp expression was almost same in the two groups, but after cancer peptide vaccination (post-vaccination), Hp expression was higher in short-term survivors, suggesting that Hp expression in the PBMCs increased in short-term survivors after treatment by cancer peptide vaccines. Our results suggest that Hp expression level in the PBMCs can serve as a prognostic biomarker in treatment by cancer peptide vaccine in advanced CRPC patients.

A Case of STAT1 Mutations in Chronic Mucocutaneous Candidiasis Diagnosed in an Adult.

A 30-year-old man presented with oral candidiasis and a history of lung abscess. He experienced recurring oral and skin candidiasis in childhood but spent long periods without any infections. Therefore, immunodeficiency was suspected. T and B lymphocyte and natural killer cell counts as well as immunoglobulin levels were normal. Human immunodeficiency virus test results were negative. Therefore, we suspected chronic mucocutaneous candidiasis (CMC). The signal transducer and activator of transcription (STAT) mutation, the leading cause of CMC, was detected by exome sequencing. Most cases of STAT-1 mutations are diagnosed in childhood, but a few are diagnosed in adulthood because Candida infections may not be severe.

Immunological evaluation of personalized peptide vaccination in refractory small cell lung cancer.

Since the prognosis of small cell lung cancer (SCLC) remains poor, development of new therapeutic approaches, including immunotherapies, would be desirable. In the current study, to evaluate immunological responses in refractory SCLC patients, we conducted a small scale phase II clinical trial of personalized peptide vaccination (PPV), in which vaccine antigens are selected based on pre-existing host immunity. Ten refractory SCLC patients, who had failed to respond to chemo- and/or chemoradiotherapies (median number of regimens, 2.5; median duration, 20.5 months), were enrolled. A maximum of four human leukocyte antigen (HLA)-matched peptides showing higher antigen-specific humoral responses were subcutaneously administered (weekly for six consecutive weeks and then bi-weekly thereafter). PPV was terminated before the 3rd administration in four patients because of rapid disease progression, whereas the remaining six patients completed at least one cycle (six times) of vaccinations. Peptide-specific immunological boosting was observed in all of the six patients at the end of the first cycle of vaccinations, with their survival time of 25, 24.5 (alive), 10 (alive), 9.5, 6.5, and 6 months. Number of previous chemotherapy regimens and frequency of CD3(+) CD26(+) cells in peripheral blood were potentially prognostic in the vaccinated patients (hazard ratio [HR] = 2.540, 95% confidence interval [CI] = 1.188-5.431, P = 0.016; HR = 0.941, 95% CI = 0.878-1.008, P = 0.084; respectively). Based on the feasible immune responses in refractory SCLC patients who received at least one cycle (six times) of vaccinations, PPV could be recommended for a next stage of larger-scale, prospective clinical trials.

Gene expression profiles in peripheral blood as a biomarker in cancer patients receiving peptide vaccination.

BACKGROUND: Because only a subset of patients show clinical responses to peptide-based cancer vaccination, it is critical to identify biomarkers for selecting patients who would most likely benefit from this treatment. METHODS: The authors characterized the gene expression profiles in peripheral blood of vaccinated patients to identify biomarkers to predict patient prognosis. Peripheral blood was obtained from advanced castration-resistant prostate cancer patients, who survived for >900 days (long-term survivors, n = 20) or died within 300 days (short-term survivors, n = 20) after treatment with personalized peptide vaccination. Gene expression profiles in prevaccination and postvaccination peripheral blood mononuclear cells (PBMCs) were assessed by DNA microarray. RESULTS: There were no statistically significant differences in the clinical or pathological features between the 2 groups. Microarray analysis of prevaccination PBMCs identified 19 genes that were differentially expressed between the short-term and long-term survivors. Among the 15 up-regulated genes in the short-term survivors, 13 genes, which were also differentially expressed in postvaccination PBMCs, were associated with gene signatures of granulocytes. When a set of 4 differentially expressed genes were selected as the best combination to determine patient survival, prognosis was correctly predicted in 12 of 13 patients in a validation set (accuracy, 92%). CONCLUSIONS: These results suggested that abnormal granulocytes present in the PBMC faction may contribute to poor prognosis in advanced prostate cancer patients receiving personalized peptide vaccination. Gene expression profiling in peripheral blood might thus be informative for devising better therapeutic strategies by predicting patient prognosis after cancer vaccines.

Identification of B cell epitopes reactive to human papillomavirus type-16L1- derived peptides.

BACKGROUND: Persistent infection of human papillomavirus (HPV) types 16 and 18 causes cervical cancer. To better understand immune responses to the prophylactic vaccine, HPV 16/18 L1 virus-like particles (HPV-VLPs), we investigated B cell epitopes of HPV16 L1-derived peptides. METHODS: Sera from mice immunized with HPV-16/18 L1 VLPs were analyzed for their IgG titers against 10 different HPV16 L1-derived peptides (20-mer) that contain human leukocyte antigen (HLA)-class I A-2, A-24 and class II DR. RESULTS: One 20-mer peptide at positions 300 to 319 was identified as a common B cell epitope in both Balb/c (H-2d) and C57BL/6 (H-2b) mice. Mapping analysis showed that the 10-amino-acid sequence at positions 304 to 313 was an immunogenic portion. It is of note that the binding capability of this 10-mer peptide to the HLA-A2 and HLA-A24 molecules was confirmed by the HLA class I stabilization assay. In addition, one unique 20-mer was determined as a B cell epitope in each strain. CONCLUSIONS: These results might provide new information for better understanding of immune responses to HPV 16 L1.

A phase I study of personalized peptide vaccination for advanced urothelial carcinoma patients who failed treatment with methotrexate, vinblastine, adriamycin and cisplatin.

OBJECTIVE: • To investigate the safety and immune responses of 12 consecutive weeks of once-weekly personalized peptide vaccine (PPV) administration in patients with advanced urothelial carcinoma (UC) for whom therapy with methotrexate, vinblastine, adriamycin and cisplatin (MVAC) has failed. PATIENTS AND METHODS: • A phase I trial was designed. Ten patients with MVAC-refractory advanced or metastatic UC were treated with weekly personalized peptide vaccine 12 times using positive peptides chosen from 14 and 16 peptides in patients with human leucocyte antigens A24 and A2, respectively. • Peptide-specific cytotoxic T lymphocyte precursor analysis by interferon-γ production and peptide-reactive immunoglobulin G (IgG) using an enzyme-linked immunosorbent assay was monitored during the treatment. RESULTS: • The peptide vaccination was safe and well tolerated with no major adverse effects. Increased cytotoxic T lymphocyte response and the anti-peptide IgG titre were revealed by the post-vaccination sera in eight patients. • Clinical responses were as follows: one complete response, one partial response, two stable disease and six progressive disease. • Median progression-free survival and overall survival were 3.0 and 8.9 months, respectively. In the four responders, median progression-free survival and overall survival were 21 and 24 months, respectively. CONCLUSIONS: • This phase I study showed the safety of and boosted immune responses in response to PPV for advanced UC. • The potential efficacy of 12 consecutive weekly vaccinations with PPV in patients with advanced UC merits further investigation based on these findings.

Integrity of plasma cell-free DNA as a prognostic factor for vaccine therapy in patients with endometrial cancer.

Endometrial cancer is the most prevalent gynecological cancer in developed countries. Although the prognosis of endometrial cancer is better than that of other gynecological cancers, the prognosis of advanced endometrial cancer is still poor and thus new therapeutic modalities, such as immune therapies, are urgently required. For the further development of new modalities, exploration of new biomarkers is important. The present study investigated the circulating cell-free DNA (cfDNA) integrity as a ratio of the necrotic tumor cell-derived long cfDNA fragments to the total dead cell-derived short cfDNA fragments from genomic Alu elements in patients with advanced endometrial cancer during peptide vaccination treatment. The results demonstrated that: i) The plasma cfDNA integrity was decreased during the first cycle of vaccination in patients with endometrial cancer treated with the personalized peptide vaccination, and ii) the post-vaccination cfDNA integrity levels were correlated with good prognosis. Some of these findings have been confirmed in other cancers, and thus cfDNA integrity might be an important marker for future cancer vaccine therapies in general, and might also be applicable for other immune therapies.

Evaluation of a new oil adjuvant for use in peptide-based cancer vaccination.

Vaccine therapies are increasingly being used for the treatment of various diseases, and the antigen molecules themselves are being expanded from whole microorganisms to fine molecules such as peptides. Accordingly, there is a need for new adjuvants to support these new applications. In this paper, we used pharmaceutical grade mineral oil and sorbitan monooleate to develop a new oil adjuvant formula, NH(2) , and investigated its effects on peptide vaccination at both the pre-clinical and clinical levels. The adjuvant effect of NH(2) on peptide-induced cellular immunity in mice was superior to that of Montanide ISA51VG, a commercially available incomplete Freund's adjuvant for clinical use, although no significant difference was observed between the two adjuvants on peptide-induced humoral immunity. The adjuvant effects of NH(2) were also confirmed in a Phase-I clinical trial of peptide vaccines for patients with advanced cancers. These results suggest that NH(2) is a suitable adjuvant for peptide vaccination, particularly for cancer vaccines (Phase-I clinical trial of pan-HLA type personalized peptide vaccine for advanced cancer patients, UMIN clinical trial registry number: UMIN 000000619).

Immunological evaluation of personalized peptide vaccination monotherapy in patients with castration-resistant prostate cancer.

We previously reported that personalized peptide vaccine (PPV) therapy in combination with leutenizing hormone-releasing hormone (LH-RH) analog and estramustine phosphate in certain cases is safe and capable of inducing both immune responses and clinical responses for metastatic castration-resistant prostate cancer (CRPC) patients. In the present study, PPV monotherapy was given to CRPC patients. Twenty-three patients with metastatic CRPC were treated with PPV without any additional treatment modalities, including LH-RH analogs. Samples were analyzed for peptide-specific cytotoxic T-lymphocyte (CTL) precursor analysis and peptide-reactive IgG. Toxicity and immunological and clinical responses were assessed on a three-monthly basis. Seventeen patients were available for immunological and clinical evaluation. The vaccines were well tolerated, with grade 3 erythema at injection sites in only one patient. Augmentation of CTL or IgG responses to at least one of the peptides was observed in six of 17 (35%) and 15 of 17 (88%) patients tested, respectively. Among 57 peptides used, 9 and 36 peptides induced CTL and IgG responses, respectively. Delayed-type hypersensitivity reaction was observed in eight of 17 patients. More than 30% prostate-specific antigen (PSA) decline was observed in four of 17 patients. Of these, one patient achieved a complete PSA response and another patient showed a partial PSA response with profound shrinking of lymph node metastases and prostate. The overall median survival time was 24 months (range, 5-37 months). These results suggest that PPV monotherapy appears to be safe and capable of inducing peptide-specific immune responses and clinical responses in CRPC patients. This trial was registered with University Hospital Medical Information Network (UMIN) number R000003339.

A randomized phase II trial of personalized peptide vaccine plus low dose estramustine phosphate (EMP) versus standard dose EMP in patients with castration resistant prostate cancer.

Personalized peptide vaccination (PPV) combined with chemotherapy could be a novel approach for many cancer patients. In this randomized study, we evaluated the anti-tumor effect and safety of PPV plus low-dose estramustine phosphate (EMP) as compared to standard-dose EMP for HLA-A2- or -A24-positive patients with castration resistant prostate cancer. Patients were randomized into groups receiving either PPV plus low-dose EMP (280 mg/day) or standard-dose EMP (560 mg/day). After disease progression, patients were switched to the opposite regime. The primary end point was progression-free survival (PFS). We randomly assigned 28 patients to receive PPV plus low-dose EMP and 29 patients to receive standard-dose EMP. Nineteen events in the PPV group and 20 events in the EMP group occurred during the first treatment. Median PFS for the first treatment was 8.5 months in the PPV group and 2.8 months in the EMP group with a hazard ratio (HR) of 0.28 (95% CI, 0.14-0.61; log-rank P = 0.0012), while there was no difference for median PFS for the second treatment. The HR for overall survival was 0.3 (95% CI, 0.1-0.91) in favor of the PPV plus low-dose EMP group (log-rank, P = 0.0328). The PPV plus low-dose EMP was well tolerated without major adverse effects and with increased levels of IgG and cytotoxic-T cell responses to the vaccinated peptides. PPV plus low-dose EMP was associated with an improvement in PSA-based PFS as compared to the standard-dose EMP alone.

Identification of biomarkers for personalized peptide vaccination in 2,588 cancer patients.

Peptide­based cancer vaccines have failed to provide sufficient clinical benefits in order to be approved in clinical trials since the 1990s. To understand the mechanisms underlying this failure, the present study investigated biomarkers associated with the lower overall survival (OS) among 2,588 patients receiving personalized peptide vaccination (PPV). Survival data were obtained from a database of 2,588 cancer patients including 399 patients with lung, 354 with prostate and 344 with colon cancer. They entered into phase II clinical trials of PPV in which 2 to 4 of 31 warehouse peptides were selected for vaccination on an individual patient basis based on human leukocyte antigen (HLA) class IA­types and pre­existing peptide­specific IgG levels. Higher pre­vaccination neutrophil, monocyte and platelet counts, and lower pre­vaccination lymphocyte and red blood cell counts were inversely associated with OS, with higher sensitivities in the proportions of neutrophils and lymphocytes, respectively. The most potent unfavorable and favorable factors for OS were the median percentage of neutrophils (≥64.8%) or percentage of lymphocytes (≥25.1%) with correlation coefficients (R2) of 0.98 and 0.92, respectively. Higher pre­vaccination levels of c­reactive protein and other inflammatory soluble factors were inversely associated with OS. Pre­vaccination peptide­specific immunity levels had no effect on OS, although lower immune boosting levels were inversely associated with OS. None of the 31 peptides was inversely associated with OS, although a few peptides were positively associated with it. On the whole, the findings of the present study suggested that pre­vaccination inflammatory signatures, but not those of post­vaccination immune induction, were associated with lower clinical benefits of PPV.

Identification of peptides applicable as vaccines for HLA-A26-positive cancer patients.

One-fifth of the Japanese population is positive for HLA-A26, but few peptides are available as potential cancer vaccines for HLA-A26-positive cancer patients. The objective of this study was to identify peptide vaccine candidates for HLA-A26-positive cancer patients. The HLA-A*2601-crossbinding activity of 24 peptides currently under clinical trial as vaccines for HLA-A2, -A24, or HLA-A3 supertype-positive cancer patients was evaluated by stabilization assay. Three peptides with HLA-A2-binding activity could bind the HLA-A*2601 molecule. These three peptides induced HLA-A26-restricted cytotoxic T lymphocytes from HLA-A*2601-, -A*2602-, or -A*2603-positive prostate cancer patients against HLA-A*2601- and HLA-A*2603-positive cancer cells in CD8-dependent and peptide-specific manners. In addition, one peptide with HLA-A24-binding activity could bind to HLA-A*2601 and induced HLA-A26-restricted cytotoxic T lymphocytes from HLA-A*2601-, -A*2602-, or -A*2603-positive prostate cancer patients against HLA-A*2603-positive cancer cells. These results may provide novel information for the development of a peptide-based cancer vaccine for HLA-A26-positive patients.

Phase I clinical study of a peptide vaccination for hepatitis C virus-infected patients with different human leukocyte antigen-class I-A alleles.

Hepatitis C virus (HCV) infection has a high risk of liver cirrhosis and hepatocellular carcinoma at later stages. We recently identified a peptide derived from the HCV core protein capable of inducing both cellular and humoral responses to nearly all HCV-positive patients in Japan with different human leukocyte antigen (HLA)-class I-A alleles. To assess the safety and immune responses to this novel peptide, we conducted a phase I dose-escalation study of the vaccination for 26 HCV-positive patients who were either non-responders to the interferon-based therapy (n = 23) or refused it (n = 3). The regimen was well tolerated, with no severe vaccine-related toxicity. Twenty-five and 22 patients completed the first and second cycle vaccination (6 and 12 vaccine injections), respectively. After a series of six vaccine injections, peptide-specific CTL activity was augmented in peripheral blood mononuclear cells from 15 of 25 patient samples, with an expected optimal dose of 1 mg peptide. After 12 vaccine injections, peptide-specific IgG production was augmented in plasma from the majority of patients (15 of 22 patients) tested, but not in a dose-dependent fashion. There were two HCV RNA responders with >1 log declines. Among patients whose pre-vaccination levels of alanine aminotransferase and alpha feto-protein exceeded the normal ranges, a <30% decrease was found in 7 of 24 and three of six patients, respectively. Because of its tolerability and higher rate of immune boosting, this protocol is recommended for a phase II study to investigate its clinical efficacy.