Quality Verification with a Cluster−Controlled Manufacturing System to Generate Monocyte−Derived Dendritic Cells

Dendritic cell (DC) vaccines for cancer immunotherapy have been actively developed to improve clinical efficacy. In our previous report, monocyte−derived DCs induced by interleukin (IL)−4 with a low−adherence dish (low−adherent IL-4−DCs: la−IL-4−DCs) improved the yield and viability, as well as relatively prolonged survival in vitro, compared to IL-4−DCs developed using an adherent culture protocol. However, la−IL-4−DCs exhibit remarkable cluster formation and display heterogeneous immature phenotypes. Therefore, cluster formation in la−IL-4−DCs needs to be optimized for the clinical development of DC vaccines. In this study, we examined the effects of cluster control in the generation of mature IL-4−DCs, using cell culture vessels and measuring spheroid formation, survival, cytokine secretion, and gene expression of IL-4−DCs. Mature IL-4−DCs in cell culture vessels (cluster−controlled IL-4−DCs: cc−IL-4−DCs) displayed increased levels of CD80, CD86, and CD40 compared with that of la−IL-4−DCs. cc−IL-4−DCs induced antigen−specific cytotoxic T lymphocytes (CTLs) with a human leukocyte antigen (HLA)−restricted melanoma antigen recognized by T cells 1 (MART−1) peptide. Additionally, cc−IL-4−DCs produced higher levels of IFN−γ, possessing the CTL induction. Furthermore, DNA microarrays revealed the upregulation of BCL2A1, a pro−survival gene. According to these findings, the cc−IL-4−DCs are useful for generating homogeneous and functional IL-4−DCs that would be expected to promote long−lasting effects in DC vaccines.

Effect of IL-15 addition on asbestos-induced suppression of human cytotoxic T lymphocyte induction

Background Asbestos fibers possess tumorigenicity and are thought to cause mesothelioma. We have previously reported that exposure to asbestos fibers causes a reduction in antitumor immunity. Asbestos exposure in the mixed lymphocyte reaction (MLR) showed suppressed induction of cytotoxic T lymphocytes (CTLs), accompanied by a decrease in proliferation of CD8+ T cells. Recently, we reported that asbestos-induced suppression of CTL induction is not due to insufficient levels of interleukin-2 (IL-2). In this study, we continue to investigate the mechanism responsible for the effect of asbestos fibers on the differentiation of CTLs and focus on interleukin-15 (IL-15) which is known to be a regulator of T lymphocyte proliferation. Methods For MLR, human peripheral blood mononuclear cells (PBMCs) were cultured with irradiated allogenic PBMCs upon exposure to chrysotile B asbestos at 5 μg/ml for 7 days. After 2 days of culture, IL-15 was added at 1 ng/ml. After 7 days of MLR, PBMCs were collected and analyzed for phenotypic and functional markers of CD8+ T cells with fluorescence-labeled anti-CD3, anti-CD8, anti-CD45RA, anti-CD45RO, anti-CD25, and anti-granzyme B antibodies using flow cytometry. To examine the effect of IL-15 on the expression level of intracellular granzyme B in proliferating and non-proliferating CD8+ lymphocytes, PBMCs were stained using carboxyfluorescein diacetate succinimidyl ester (CFSE) and then washed and used for the MLR. Results IL-15 addition partially reversed the decrease in CD3+CD8+ cell numbers and facilitated complete recovery of granzyme B+ cell percentages. IL-15 completely reversed the asbestos-induced decrease in percentage of granzyme B+ cells in both non-proliferating CFSE-positive and proliferating CFSE-negative CD8+ cells. The asbestos-induced decrease in the percentage of CD25+ and CD45RO+ cells in CD8+ lymphocytes was not reversed by IL-15. Conclusion These findings indicate that CTLs induced upon exposure to asbestos possess dysfunctional machinery that can be partly compensated by IL-15 supplementation, and that IL-15 is more effective in the recovery of proliferation and granzyme B levels from asbestos-induced suppression of CTL induction compared with IL-2.

Phase II open-label study of S-588410 as maintenance monotherapy after first-line platinum-containing chemotherapy in patients with advanced or metastatic urothelial carcinoma.

440 Background: S-588410 is a cancer peptide vaccine composed of 5 human leukocyte antigen (HLA)-A*24:02-restricted epitope peptides derived from 5 cancer-testis antigens: DEPDC1, MPHOSPH1, URLC10, CDCA1 and KOC1; all of which are highly expressed in urothelial carcinoma. This study aimed to evaluate the effect of S-588410 maintenance therapy on peptide-specific cytotoxic T-lymphocyte (CTL) induction in patients with advanced or metastatic urothelial carcinoma after first-line platinum-based chemotherapy. Methods: An open-label, multicenter phase II trial was performed across 62 sites in Japan, the United Kingdom, France and Bulgaria (EudraCT 2013-005274-22). Eligible patients had completed ≥4 cycles of first-line platinum-based chemotherapy without disease progression. HLA-A*24:02-positive patients received S-588410 (1 mg of each of 5 peptides mixed with Montanide ISA 51 VG) subcutaneously weekly for 12 weeks, then every 2 weeks for up to 2 years. HLA-A*24:02-negative patients were enrolled in an observation group and did not receive study drug. The primary endpoint for the S-588410 group was the CTL induction rate at 12 weeks, defined as the proportion of patients who showed increased CTL activity for ≥1 peptide. Secondary endpoints included CTL induction rate after 1 year, antitumor effect defined by immune-related response criteria, progression-free survival (PFS), overall survival (OS), and safety. Results: A total of 81 patients with platinum-sensitive advanced or metastatic urothelial carcinoma were enrolled (S-588410 group, n=45; observation group, n=36) between April 2014 and November 2017. Most patients were male and Asian with a mean age of 67 years. CTLs were induced in 42 (93.3%) patients who received S-588410 for 12 weeks (P<0.0001, one-sided binomial test where the CTL induction rate is ≤50% as the null hypothesis). The CTL induction rate steadily increased to 95.6% within 48 weeks. CTL activity was high for the DEPDC1, MPHOSPH1 and URLC10 peptides. The response rate (immune-related complete response [CR] or partial response [PR]) was 8.9% (4/45 patients) in the S-588410 group and 0% in the observation group. Tumor imaging showed gradual (PR, n=3) and durable (CR, n=1) tumor shrinkage after ≥36 weeks in the S-588410 group. Median PFS was 18.1 weeks in the S-588410 group and 12.5 weeks in the observation group. Median OS was 71 and 99 weeks, respectively. The most frequent treatment-emergent adverse event was injection site reaction (42/45 patients [93.3%]; Grades 1–3). Pyrexia, rash and pruritus were also observed in the S-588410 group, but not the observation group. Conclusions: S-588410 showed a potent immune response and acceptable safety profile in patients with advanced or metastatic urothelial carcinoma, potentially offering a clinical benefit as post-chemotherapy maintenance therapy. Clinical trial information: EudraCT 2013-005274-22.

TAS0314, a novel multi-epitope long peptide vaccine, showed synergistic antitumor immunity with PD-1/PD-L1 blockade in HLA-A*2402 mice

Cancer peptide vaccines are a promising cancer immunotherapy that can induce cancer-specific cytotoxic T lymphocytes (CTLs) in tumors. However, recent clinical trials of cancer vaccines have revealed that the efficacy of the vaccines is limited. Targeting single antigens and vaccination with short peptides are partly the cause of the poor clinical outcomes. We synthesized a novel multi-epitope long peptide, TAS0314, which induced multiple epitope-specific CTLs in HLA knock-in mice. It also showed superior epitope-specific CTL induction and antitumor activity. We also established a combination treatment model of vaccination with PD-1/PD-L1 blockade in HLA-A*2402 knock-in mice, and it showed a synergistic antitumor effect with TAS0314. Thus, our data indicated that TAS0314 treatment, especially in combination with PD-1/PD-L1 blockade, is a promising therapeutic candidate for cancer immunotherapy.

Induction of tumor-specific CD8+ cytotoxic T lymphocytes from naïve human T cells by using Mycobacterium-derived mycolic acid and lipoarabinomannan-stimulated dendritic cells

The main effectors in tumor control are the class I MHC molecule-restricted CD8+ cytotoxic T lymphocytes (CTLs). Tumor-specific CTL induction can be regulated by dendritic cells (DCs) expressing both tumor-derived epitopes and co-stimulatory molecules. Immunosuppressive tolerogenic DCs, having down-regulated co-stimulatory molecules, are seen within the tumor mass and can suppress tumor-specific CTL induction. The tolerogenic DCs expressing down-regulated XCR1+CD141+ appear to be induced by tumor-derived soluble factors or dexamethasone, while the immunogenic DCs usually express XCR1+CD141+ molecules with a cross-presentation function in humans. Thus, if tolerogenic DCs can be reactivated into immunogenic DCs with sufficient co-stimulatory molecules, tumor-specific CD8+ CTLs can be primed and activated in vivo. In the present study, we converted human tolerogenic CD141+ DCs with enhanced co-stimulatory molecule expression of CD40, CD80, and CD86 through stimulation with non-toxic mycobacterial lipids such as mycolic acid (MA) and lipoarabinomannan (LAM), which synergistically enhanced both co-stimulatory molecule expression and interleukin (IL)-12 secretion by XCR1+CD141+ DCs. Moreover, MA and LAM-stimulated DCs captured tumor antigens and presented tumor epitope(s) in association with class I MHCs and sufficient upregulated co-stimulatory molecules to prime naïve CD3+ T cells to become CD8+ tumor-specific CTLs. Repeat CD141+ DC stimulation with MA and LAM augmented the secretion of IL-12. These findings provide us a new method for altering the tumor environment by converting tolerogenic DCs to immunogenic DCs with MA and LAM from Mycobacterium tuberculosis.

Cancer peptide vaccine to suppress postoperative recurrence in esophageal SCC patients with induction of antigen-specific CD8+ T cell.

e14635 Background: This is a following report of the exploratory phase II study of adjuvant peptide vaccine for thoracic esophageal squamous cell carcinoma (TESCC) (abstract #3087 in ASCO2016), focusing on an association of immunological responses with clinical outcomes. Three HLA-A-24-restricted epitope peptides derived from cancer-testis antigens, up-regulated lung cancer 10 (URLC10), cell division cycle associated 1 (CDCA1) and KH domain-containing protein overexpressed in cancer 1 (KOC1), were used in this study. Methods: TESCC patients who underwent neoadjuvant therapy followed by curative resection (Dec./2009 to Sep./2014) and were found LN metastasis were enrolled. One mg each of three peptides mixed with Montanide was injected to patients with HLA-A*2402 20 times in a 6-months period. No other adjuvant therapy was given until recurrence occurred. Primary endpoint is relapse-free survival (RFS). Immunological responses were examined by ELISPOT assay and immunohistochemistry (IHC). Results: 33 patients were enrolled in the vaccine group (VG) and 30 with non-HLA-A*2402 were used as controls (CG). There was no significant difference in clinical backgrounds between the two groups. 5-year RFS in the VG was 44.6% while that in the CG group was 31.6% (p = 0.207); patients who showed CD8+ CTL induction to multiple peptides tend to show better RFS rate [3/2/1 peptides = 69.0(n = 20)/46.8(n = 11)/0%(n = 2), respectively]. Five-year esophageal cancer-specific survival (ECSS) were 58.4% in the VG compared with 35.4% in the CG (p = 0.156); 90.0% (n = 11) vs. 50.0% (n = 15) and 43.8% (n = 22) vs. 24.0%(n = 15) in pN1 and pN2-3 groups, respectively. Regarding the CD8+ positivity, ECSS was improved only in the negative group (56.6% in VG vs. 26.7% in CG). Classification by T cell positivity and PD-L1 expression [type I(+/+), II(-/-), III(-/+) and IV(+/-)] showed 5-year ECSS to be 100%(n = 3), 66.4%(n = 19), 20.0%(n = 5) and 44.4%(n = 6). Conclusions: Our cancer peptide vaccines induced the antigen-specific CD8+ T cell highly and efficiently, and suppressed recurrence with the strong immune responses. Clinical trial information: UMIN000003557.

Preliminary Results from a Phase 1/2 Study of DSP-7888, a Novel WT1 Peptide-Based Vaccine, in Patients with Myelodysplastic Syndrome (MDS)

Background: Hypomethylating agents (HMA), including azacitidine (AZA) are currently the first-line treatment option for higher-risk myelodysplastic syndrome (MDS). However, the prognosis of patients after AZA failure is poor with a median overall survival of 5.6 months from the treatment failure (J Clin Onclol 2011;29:3322-7 Prébet T et al.), and currently there are no approved therapeutic options for such patients. Suzuki et al. reported that WT4869, one of the HLA-A*24;02-restricted synthetic peptide vaccine derived from Wilms' tumor 1 (WT1) protein, demonstrated the sign of prolongation of overall survival (OS) with a median OS of 13.0 months in AZA failure higher-risk population, in the phase 1/2 study with MDS patients (Blood 126:2868, 2015;Suzuki et al.). DSP-7888 is a novel WT1-based peptide vaccine which induces the CTLs that recognize WT1 antigens in HLA-A*02:01/06 and HLA-A*24:02 restricted manner, and also includes a WT1-derived helper peptide applicable for various subtypes of HLA-DRB1. DSP-7888 is currently being investigated in a phase 1/2 study to evaluate the safety and efficacy in HLA-A*24:02+ and/or HLA-A*02:01/:06+ MDS patients, with some exploratory biomarker analyses. Methods: The objectives of this study were to assess the tolerability of DSP-7888 treatment in MDS patients in the phase 1 portion and to evaluate preliminary clinical activity of DSP-7888 in higher-risk MDS patients after AZA failure in the study. In phase 1 portion, higher-risk or transfusion-dependent lower-risk MDS patients including the AZA failure population were enrolled, and DSP-7888 was administered at doses of 3.5 to 10.5 mg/body by intradermal injections every two to four weeks in dose-escalation cohorts according to the 3 + 3 design until discontinuation criteria were met. Overall survival was evaluated for primarily clinical activity and hematological response and time to AML were also examined. Delayed type hypersensitivity (DTH), WT1-specific CTL induction and expression of WT1 mRNA in peripheral blood and bone marrow cells were also evaluated as exploratory biomarkers. The clinical data in phase 1 portion as of May 25th 2016 was presented in this report. Results: In phase 1 portion, enrollment of patients and dose-limiting toxicities (DLTs) evaluation were completed. Twelve patients including 7 higher- and 5 lower-risk patients were enrolled in 3.5 and 10.5 mg/body cohorts of 6 patients each, and safety profiles were evaluated. DLTs were not observed in either cohorts and the most common adverse drug reaction (ADR) was injection site reaction (ISR). ISR in 6 patients worsened to grade 3 with continuous treatment of DSP-7888 (2 patients at 3.5 mg/body, and 4 patients at 10.5 mg/body). Five serious ADR including 3 ISR, 1 pyrexia and 1 myocarditis were reported and dose-dependent toxicity was not observed except for ISR. All 12 patients were analyzed for preliminary clinical activity. Eight patients remained in stable disease (SD) with 2 hematological improvements (HI), and disease control rate (SD + any HI) was 66.6 %. Seven high risk AZA failure patients were enrolled, and the current survival time in this population is 7.3-10.8 months. Though preliminary, CTL induction was observed in 6 patients, and a trend of higher CTL induction was observed in patients with grade 3 ISR. DTH response was observed in 10 patients. Conclusions: In the phase 1 portion, DSP-7888 was well-tolerated in MDS patients although ISR was observed in all patients. CTL induction was detected with clinically observed reactions that may suggest preliminary signs of clinical activity. Further evaluation is needed to confirm the clinical potential of DSP-7888, and phase 2 portion is currently ongoing to evaluate the efficacy of DSP-7888 in higher-risk MDS patients after AZA failure. Disclosures Usuki: Nippon Shinyaku: Honoraria; MSD: Honoraria; Kyouwa-Kirin: Honoraria; Novartis: Honoraria; Bristol-Myer-Squibb: Honoraria; Sumitomo Dainippon Pharma: Honoraria; SymBio Pharmaceuticals: Research Funding. Matsumura:Bristol-Myers Squibb Company: Honoraria; Novartis Pharma K.K: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Consultancy, Honoraria; Pfizer Japan Inc.: Honoraria. Ueda:Alexion Pharmaceuticals Inc.: Membership on an entity's Board of Directors or advisory committees. Origuchi:Sumitomo Dainippon Pharma Co.,Ltd.: Employment. Tagashira:Sumitomo Dainippon Pharma Co.,Ltd.: Employment. Naoi:Sumitomo Dainippon Pharma Co.,Ltd.: Employment. Naoe:Bristol-Myers Squibb: Honoraria; Sumitomo Dainippon Pharma Co.,Ltd.: Honoraria, Research Funding; Pfizer Inc.: Research Funding; Astellas Pharma Inc.: Research Funding; Kyowa-Hakko Kirin Co.,Ltd.: Honoraria, Patents & Royalties, Research Funding; Amgen Astellas BioPharma K.K.: Honoraria; Otsuka Pharmaceutical Co.,Ltd.: Honoraria, Research Funding; CMIC Co., Ltd.: Research Funding; Celgene K.K.: Honoraria, Research Funding; TOYAMA CHEMICAL CO.,LTD.: Research Funding; Chugai Pharmaceutical Co.,LTD.: Honoraria, Patents & Royalties; Nippon Boehringer Ingelheim Co., Ltd.: Honoraria, Research Funding; Fujifilm Corporation: Honoraria, Patents & Royalties, Research Funding. Heike:Sumitomo Dainippon Pharma: Consultancy; Chugai Pharma: Consultancy; Otsuka Pharma: Consultancy. Miyazaki:Kyowa Kirin: Honoraria; Nihonshinyaku: Honoraria; Celgene Japan: Honoraria; Sumitomo Dainippon Pharma Co.,Ltd.: Honoraria.

A Phase 1/2 Study of WT1 Peptide Cancer Vaccine WT4869 in Patients with Myelodysplastic Syndromes (MDS)

Background: Based on its favorable effects on survival, azacitidine (AzaC) is now recognized as a first-line treatment option for higher-risk MDS. But the prognosis of patients who become resistant or intolerant to AzaC is still dismal (the median overall survival was 5.6 months, J Clin Onclol 2011;29:3322-7 Prebet T et. al.), and development of effective salvage therapies is eagerly awaited. A large number of tumor-associated antigens (TAAs) have been identified, and cancer vaccines utilizing their epitopes have shown some degree of clinical efficacies in various types of tumors. Wilms' Tumor 1 (WT1) is one of such promising TAAs with broad expressions in various tumors including MDS. WT4869 is a synthetic peptide vaccine derived from WT1 protein, and the phase 1/2 clinical study of WT4869 was conducted to evaluate the safety and efficacy in HLA-A*24:02+ MDS patients, with some exploratory biomarker analyses. Methods: The objectives of this study were to assess the tolerability of WT4869 treatment in MDS patients in phase 1 portion and evaluate the preliminary efficacy of WT4869 in higher-risk MDS patients in phase 2 portion. Higher-risk or transfusion-dependent lower-risk MDS patients including the AzaC-resistant population were enrolled in the study, and WT4869 at a dose of 5 to 1,200 µg/body was administered with intradermal injections every two weeks in dose-escalation cohorts according to the 3 + 3 design until discontinuation criteria were met. Clinical efficacy was evaluated according to the IWG response criteria 2006, and the time to acute myeloid leukemia and overall survival (OS) were also analyzed. We also evaluated immune responses including delayed type hypersensitivity and WT1-specific CTL induction. Expression of WT1 mRNA in peripheral blood and bone marrow cells were analyzed as surrogate markers for clinical efficacy. Results: Twenty six patients including 17 higher- and 9 lower-risk patients were enrolled in the study, and safety profiles were evaluated. Although dose-limiting toxicities (DLTs), including pneumonitis, muscle hemorrhage, pyrexia, and hypoalbuminemia, were observed in one patient at each dose of 50 and 400 µg/body, all of them were confirmed to be resolved or resolving, and no DLT was observed at other doses. As a result, WT4869 treatment was considered well-tolerated at the highest dose of 1,200 µg/body in MDS patients. Although there was no safety concern noted in phase 1 portion, further enrollment in phase 2 portion was not conducted to focus on the development with newly designed WT1 peptide vaccine. Twenty two out of 26 patients were analyzed for clinical efficacy. Decrease of bone marrow blasts was observed in one patient (marrow complete remission (mCR)), and 12 patients remained in stable disease (SD). Hematological improvement (HI) was observed in one mCR and three SD patients; two were in the erythroid lineages, one in the erythroid and neutrophil lineage and the other in the all three lineages. Very interestingly, two patients showed cytogenetic response, although hematopoietic improvement was not observed in these patients. In total, the overall response rate (mCR + any HI) was 18.2%, and the disease control rate (mCR + SD + any HI) was 59.1%. Though preliminary, prolongation of OS was observed in higher-risk patients and the median survival time in the AzaC-resistant higher-risk population was 13.0 months. CTL induction was observed in almost half of the treated population, and patients with any clinical response showed a trend of higher CTL induction. Conclusions: In the phase 1/2 study, WT4869 was well-tolerated in MDS patients, and preliminary but promising efficacy was suggested. WT1 peptide vaccination is expected to be a new treatment option for AzaC-resistant MDS. Further evaluations of WT1 peptide vaccination are warranted. Disclosures Ogura: Kyowa Hakko Kirin co., Ltd.: Research Funding; Eisai Co., Ltd.: Research Funding; Zenyaku Kogyo Co., Ltd.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Phizer Japan Inc.: Research Funding; Janssen Pharmaceutical K.K.: Research Funding; GlaxoSmithKline K.K.: Research Funding; MSD K.K.: Research Funding; AstraZeneca K.K.: Research Funding; Takeda Pharmaceutical Company Limited: Research Funding; Symbio Pharmaceuticals Limited: Research Funding; Solasia Phama K.K.: Research Funding; Mundipharma K.K.: Research Funding; Celgene K.K.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding. Uchida:Eisai Co., Ltd.: Research Funding. Naoe:Kyowa Hakko Kirin Co., Ltd.: Patents & Royalties, Research Funding; Nippon Boehringer Ingelheim Co., Ltd.: Research Funding; Celgene K.K.: Research Funding; Toyama Chemical CO., LTD.: Research Funding; FUJIFILM Corporation: Patents & Royalties, Research Funding; Chugai Pharmaceutical Co., Ltd.: Patents & Royalties; Astellas Pharma Inc.: Research Funding; Otsuka Pharmaceutical Co., Ltd.: Research Funding; Pfizer Inc.: Research Funding. Kizaki:Ono Phranacutical Co., Ltd.: Consultancy; Nippon Shinyaku Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Research Funding; Chugai Phrarmaceutical Co., Ltd.: Research Funding. Tagashira:Sumitomo Dainippon Pharma Co.,Ltd.: Employment. Tsuchiya:Sumitomo Dainippon Pharma Co., Ltd.: Employment. Ohyashiki:Asahikasei: Research Funding; Teijin Pharma KK: Research Funding; Alexion Pharma KK: Research Funding; Asteras: Research Funding; Shinbaio Pharma KK: Honoraria; Toyama Kagaku KK: Speakers Bureau; Nippo Shinyaku KK: Speakers Bureau; MSD KK: Honoraria; Kyowa Kirin KK: Honoraria; Novartis Pharma KK: Honoraria, Research Funding, Speakers Bureau; Celegen KK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jansen Pharma KK: Honoraria, Research Funding, Speakers Bureau; Bristol Meyer Squib KK: Research Funding; Chugai Pharna KK: Research Funding; Sumitomo Dainippon: Membership on an entity's Board of Directors or advisory committees; Taiho Yakuhin KK: Research Funding. Miyazaki:Sumitomo Dainippon: Honoraria; Celgene Japan: Honoraria; Kyowa-Kirin: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Shin-bio: Honoraria.

A phase I/II study of OTSGC-A24 combined peptide vaccine in advanced gastric cancer.

65 Background: The aim of this study was to evaluate the safety and optimal dosing schedule of a HLA-restricted cancer vaccine cocktail, OTSGC-A24 targeting novel specific tumor antigens FOXM1, DEPDC1, KIF20A, URLC10 and VEGFR1 in advanced gastric cancer patients with HLA-2402 haplotype. Methods: The vaccine was administered subcutaneously at 3-weekly, 2-weekly and weekly interval. In the first phase, 3 evaluable patients were treated in each dose cohort. The decision to expand the 2-weekly and weekly cohort to 10 patients per cohort was based on specific cytotoxic T-lymphocyte (CTL) induction rate using ELISPOT assay 4 weeks after vaccination. Results: The vaccine was well tolerated at all dose cohorts. The most common toxicity seen was skin induration at the injection sites. No DLT was observed. One patient developed G2 interstitial pneumonitis, 6 months after initiation of treatment. Stable disease was seen in 4 of 9 evaluable patients. The specific CTL induction can be observed at 4 weeks post vaccination with the highest (>2 of 3) observed in the weekly and 2-weekly cohorts. One of 3 patients in the 3-weekly cohort achieved specific CTL response at 4 weeks post vaccination, although all patients attained specific CTL response by 12 weeks after vaccination. Conclusions: OTSGC-A24 combined peptide vaccine was well tolerated. At 4 weeks post vaccination, the CTL induction rate is superior in the weekly and 2-weekly cohort. Efficacy data of the expanded cohorts will be presented. Clinical trial information: NCT01227772.