Peptide Vaccination In Patients Research Articles

Spontaneous high clonal expansion of Wilms’ tumor gene 1-specific cytotoxic T-lymphocytes in patients with Wilms’ tumor gene 1-expressing solid tumor

Wilms’ tumor protein 1 (WT1)-targeted immunotherapy has been used in patients with leukemia and solid tumors. However, the spontaneous WT1-specific immune response before WT1 peptide vaccination in patients with WT1-expressing tumors (PTs) remains unclear. Therefore, we investigated whether WT1-specific cytotoxic CD8+ T-lymphocytes (CTLs) are clonally expanded in the peripheral blood outside of tumor sites. Clonal expansion of WT1126 peptide (a.a.126–134)-specific CTLs (WT1126-CTLs) was compared between seven PTs and five healthy volunteers (HVs), and their T-cell receptors (TCRs) were analyzed at the single-cell level. Overall, 433 and 351 TCR β-chains of WT1126-CTLs were detected from PTs and HVs, respectively, and complementarity-determining region 3 was sequenced for clonality analysis. The frequencies of WT1126-CTLs were higher in human leukocyte antigen (HLA)-A*02:01+ PTs than in HLA-A*02:01+ HVs, although the difference was not statistically significant. WT1126-CTLs of differentiated types, including memory and effector, were higher in PTs than in HVs; whereas, those of the naïve type were higher in HVs than in PTs. WT1126-CTL clonality was significantly higher in PTs than in HVs. Furthermore, the frequency of effector WT1126-CTLs positively correlated with WT1126-CTL clonality in PTs; whereas, the frequency of naïve phenotype WT1126-CTLs tended to be negatively correlated with clonality. In conclusion, these results suggest that the WT1 protein in tumor cells is highly immunogenic, thereby stimulating endogenous naïve-type WT1126-CTLs and enabling them to clonally expand and differentiate into effector-type WT1126-CTLs.

Phase I/II Study of a Vascular Endothelial Growth Factor Receptor Vaccine in Patients With NF2-Related Schwannomatosis.

The humanized antivascular endothelial growth factor (VEGF) antibody bevacizumab (Bev) is efficacious for the treatment of NF2-related schwannomatosis (NF2), previously known as neurofibromatosis type 2. This study evaluated the safety and efficacy of a VEGF receptor (VEGFR) vaccine containing VEGFR1 and VEGFR2 peptides in patients with NF2 with progressive schwannomas (jRCTs031180184). VEGFR1 and VEGFR2 peptides were injected subcutaneously into infra-axillary and inguinal regions, once a week for 4 weeks and then once a month for 4 months. The primary end point was safety. Secondary end points included tolerability, hearing response, imaging response, and immunologic response. Sixteen patients with NF2 with progressive schwannomas completed treatment and were assessed. No severe vaccine-related adverse events occurred. Among the 13 patients with assessable hearing, word recognition score improved in five patients at 6 months and two at 12 months. Progression of average hearing level of pure tone was 0.168 dB/mo during the year of treatment period, whereas long-term progression was 0.364 dB/mo. Among all 16 patients, a partial response was observed in more than one schwannoma in four (including one in which Bev had not been effective), minor response in 5, and stable disease in 4. Both VEGFR1-specific and VEGFR2-specific cytotoxic T lymphocytes (CTLs) were induced in 11 patients. Two years after vaccination, a radiologic response was achieved in nine of 20 assessable schwannomas. This study demonstrated the safety and preliminary efficacy of VEGFR peptide vaccination in patients with NF2. Memory-induced CTLs after VEGFR vaccination may persistently suppress tumor progression.

A phase I study of a mutant KRAS-targeted long peptide vaccine in patients at high risk of developing pancreatic cancer.

TPS758 Background: KRAS mutations are identified in the majority of premalignant lesions that precede pancreatic ductal adenocarcinoma (PDAC). Arising during tumorigenesis, mutant KRAS (mKRAS) neoantigens are less susceptible to central tolerance mechanisms and serve as ideal vaccine targets. Indeed, targeting mKRAS neoantigens with vaccines has shown promising anti-tumor activity in the preclinical setting. For instance, our group previously demonstrated that a Listeria-based vaccine targeting mKRAS G12D combined with Treg-depleting agents can prevent the progression of early pancreatic intraepithelial neoplasia to overt PDAC in a mouse model (Keenan et al, 2014). Building upon this work, the current study aims to determine the safety and immunogenicity of a pooled synthetic long peptide (SLP) mKRAS vaccine in patients identified as high risk for developing PDAC based on family history and germline mutation testing. Methods: This is a single-arm, open-label phase I trial evaluating a pooled SLP mKRAS vaccine in patients at high risk of developing PDAC ( n = 20). The vaccine consists of poly-ICLC adjuvant admixed with SLPs corresponding to six common mKRAS subtypes: G12D, G12R, G12V, G12A, G12C, and G13D. A four-dose series of the mKRAS vaccine is administered on weeks 1, 3, 4, and 17. Following completion of the treatment phase, all patients have the option to continue annual follow-up visits until study closure. Eligible patients must have radiographic evidence of a premalignant pancreatic lesion and fall under at least one of the following three high-risk groups: 1) ≥ 2 familial pancreatic cancer relatives, 2) germline mutation carriers with ≥ 10% lifetime PDAC risk and 3) germline mutation carriers with ~5% lifetime PDAC risk. The co-primary endpoints of this study are safety and T cell response. Safety will be assessed by the frequency and grading of adverse events per NCI CTCAE v5.0. T cell response will be determined by the maximal percent change in IFNγ-producing mKRAS-specific T cell density within 16 weeks post-vaccination compared to baseline. Correlative studies will explore vaccine-associated changes in T cell quality (e.g., memory, exhaustion, poly-functionality, and activation) using mass cytometry analysis of peripheral blood samples. Patient accrual began in April 2022 and is currently ongoing. Clinical trial information: NCT05013216 .

Abstract IA001: Intercepting pancreatic cancer development with oncogene targeted immunotherapy

Abstract Pancreatic adenocarcinoma (PDAC) progression is triggered by a complex interaction of genetic mutations, stromal cell interactions and tumor microenvironmental (TME) signals. Diagnosis usually occurs late in disease progression, making treatment challenging and survival rates extremely poor. PDACs are also considered non-immunogenic, therefore newly emerging immunotherapies that have been successful in other cancers have not significantly progressed PDAC treatment options. Resistance to immunotherapies progresses as normal cells undergo the earliest genetic changes that transform them into early pre-malignant lesions. The two most common premalignant lesions are pancreatic intra-epithelial neoplasms (PanINs) and intraductal papillary mucinous neoplasm (IPMN). Both types of premalignant lesions eventually accumulate additional genetic changes that lead to early-stage invasive cancer and eventually, to late stage PDAC. This transformation process is influenced by both tumor-intrinsic and extrinsic forces within the developing TME. Accumulating data suggests that immune resistance mechanisms also evolve with this progression, which has led to the hypothesis that early immune intervention may be the best time to intervene to slow or even halt disease progression and improve treatment outcomes. We know that tumor initiation to metastases takes years to decades, providing a unique window of opportunity for the prevention of premalignant progression. KRAS mutations are an early oncogenic event present in over 90% of PanINs and 75% of IPMNs. Initial studies examining cancer vaccines targeted to early oncogenic mutations are showing promise in animal models. A listeria-based vaccine engineered to express oncogenic KrasG12D combined with and without regulatory T cell depletion by an anti-CD25 antibody (PC61) and cyclophosphamide showed increased T cell infiltration, decreased disease progression, and increased survival in Kras-driven and p53 mutated genetically engineered mice (KrasG12D/+Trp53R172H/+;Pdx-1-Cre (KPC) mice) with early PanIN lesions but not those with later stage PanINs (Keenan et. al. 2014. Gastroenterology 146: 1784). Other early oncogenic mutations in PDACs may prove to be therapeutic targets for vaccine development. We recently initiated a pilot study to examine the feasibility and safety of targeting mKRAS in patients with resected PDAC. For this, we developed a clinical–grade pooled peptide vaccine targeting 6 common KRAS mutations. This vaccine has been tested in combination with checkpoint blockade in 10 PDAC patients who had undergone surgery plus peri–operative chemotherapy and had remained disease–free (NCT04117087). Longitudinal immune phenotyping showed a robust peripheral mKRAS–specific T cell response against the most vaccinated epitopes. Flow cytometry revealed that these CD4 and CD8 T cells were activated, polyfunctional and displayed a memory phenotype. Based on the favorable immunogenicity and safety profile of our peptide vaccine in patients with resected PDAC, we have initiated a Prevention Study testing our mKRAS vaccine in individuals at high risk for PDAC. This study is currently enrolling and early results will be described. Citation Format: Elizabeth M. Jaffee. Intercepting pancreatic cancer development with oncogene targeted immunotherapy [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA001.

Abstract IA013: Intercepting pancreatic cancer development with mutant KRAS-targeted immunotherapy

Abstract The evolution of pancreatic ductal adenocarcinoma (PDAC) from tumor initiation to metastases requires years to decades, providing a window of opportunity for the prevention of premalignant progression. One of the first genetic mutations to occur early in development is in KRAS, an oncogene that is expressed by over 90% of PDACs. KRAS mutations (mKRAS) are attractive targets as they are recurrent hot–spot drivers that are expressed by, and drive the growth of all PDAC cells. Preclinical data provide compelling evidence that targeting mKRAS proteins using a Listeria-based vaccination approach in KPC mouse model results in prevention of progression from precursor lesions to PDAC. Based on these data, we hypothesize that targeting mKRAS in combination with bypassing early immune–suppressive signals will slow or even halt the progression of precursor lesions to PDA in subjects who are at high–risk. We have thus developed a clinical–grade long peptide vaccine targeting the six most common mKRAS proteins (G12V, G12R, G12A, G12C, G12D, and G13D) in PDAC patients. To establish initial safety and immunogenicity, our KRAS vaccine has been tested in 11 patients thus far in a Phase 1 clinical trial (NCT04117087) in combination with checkpoint blockade in patients who have undergone surgery and peri–operative chemotherapy and remained disease–free on imaging. Longitudinal immune data demonstrates an induction of activated and poly-functional mKRAS-specific CD4+ and CD8+ T cells, as well as effector and central memory T cells post–vaccination. In parallel, we performed paired single-cell RNA and TCR sequencing in PBMCs from a patient to obtain greater resolution of the vaccine–induced cytotoxic anti–tumor T cells. We captured 66,869 immune cells across three timepoints for analysis. Notably, we similarly observed an expansion of central memory CD4+ and CD8+ T cells post–vaccination. Using a novel computational algorithm (developed in collaboration with Dr. Elana Fertig’s lab) that takes into account physiochemical similarity of known mKRAS TCRs, we used our single–cell dataset to identify mKRAS-reactive TCRs` in the periphery that were functionally validated in vitro using CRISPR-Cas12a-based genome editing of human T cells. Overall, these studies suggest the induction of de novo, high quality mutant KRAS–specific T cells in the peripheral blood post–vaccination. Based on these immune data, we are enrolling onto a second clinical trial testing our mKRAS peptide vaccine in patients who are at high risk for developing PDAC (NCT05013216). These high-risk groups include those with strong family histories of PDAC or known pathogenic germline variants with a lifetime risk of up to 10% of developing PDA. Our preliminary data in our first three vaccinated patients shows an induction of mKRAS–specific T cell responses in the peripheral blood. Further studies characterizing the T cell response will lay the foundation for peripheral T cell–based biomarkers that could be used to predict response in a prevention setting. Citation Format: Neeha Zaidi, Amanda Huff, Emily Marcisak-Davis, Daniel Haldar, Thatcher Heumann, Max Konig, Brian Mog, Janelle Montagne, Gabriella Longway, Lalitya Andaloori, Melissa Lyman, Ludmila Danilova, Julie Nauroth, Luciane Kagohara, Elana Fertig, Nilo Azad, Elizabeth Jaffee. Intercepting pancreatic cancer development with mutant KRAS-targeted immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr IA013.

IMMU-06. TARGETING IDH1 MUTANT GRADE II RECURRENT GLIOMAS USING A PEPTIDE VACCINATION STRATEGY

Abstract INTRODUCTION While primary GBM is largely heterogeneous and devoid of homogeneously expressed neoantigens, mutant IDH1 (R132H) is a uniformly expressed hallmark in >70% of low grade gliomas. As such, IDH1 mutations represent a potentially valuable vaccination target. METHODS Here, we report an update on the immunogenicity results of the mutant IDH1 peptide vaccine alone and in combination with temozolomide (TMZ). In the phase I RESIST clinical trial (NCT02193347), patients with recurrent and resectable IDH1 R132H mutant grade 2 glioma received peptide vaccinations composed of 500 µg of mutant IDH1 peptide and 150 µg of GM-CSF mixed 1:1 with Montanide adjuvant prior to surgical resection. Vaccines 1, 2, and 3 were given 15 (+/-) 3 days apart. 7-12 days after vaccine 3, patients underwent standard of care tumor (SOC) resection. After resection, patients with grade 2 gliomas were given up to 15 doses of peptide vaccine in combination with TMZ regimens while patients with transformed grade 3 gliomas were given up to 15 doses of peptide vaccine in combination with SOC radiation therapy + TMZ regimens. T cell responses against the mutant peptide were measured after vaccine 3 using IFN-γ ELISPOT and intracellular flow cytometry for IL-2, TNFα,and IFNγ. RESULTS 3/20 patients were taken off the study before completion of study related activities. 1/20 patients progressed before completion of all vaccines. Out of 134 total doses of vaccine delivered, only one dose generated a grade 2 or higher injection site reaction according to the CTCAE guidelines. Vaccination with the mutant peptide led to an overall increase in IFN-γ+ spot-forming splenocytes specific to the mutant peptide (p=0.0408). CONCLUSION Administering the mutant IDH1 peptide vaccine in patients with recurrent IDH-mutant gliomas was able to induce anti-IDH1 R132H immune responses in this initial phase I study.

A Pilot Study of the Adverse Events Caused by the Combined Use of Bevacizumab and Vascular Endothelial Growth Factor Receptor-Targeted Vaccination for Patients with a Malignant Glioma.

Anti-angiogenic therapy, targeting vascular endothelial growth factor (VEGF)-A/VEGF receptors (VEGFRs), is beneficial for tumor growth prevention in a malignant glioma. A simultaneous blockade using both bevacizumab (Bev), which targets circulating VEGF-A, and a multi-kinase inhibitor on VEGFRs was more effective for advanced solid cancers, including melanoma and renal cell carcinoma. However, previous clinical trials demonstrated a high adverse event rate. Additionally, no studies previously assessed treatment efficacy and safety using both VEGF-A and VEGFR-targeted agents for malignant gliomas. We had conducted clinical trials investigating VEGFRs peptide vaccination in patients with malignant gliomas, in which the treatment exhibited safety and yielded therapeutic effects in some patients. The combined use of Bev and VEGFRs vaccination may enhance the anti-tumor effect in malignant gliomas. In this pilot study, the adverse event profile in patients treated with Bev after the vaccination was investigated to establish this treatment strategy, in comparison to those treated with Bev collected from the published data or treated with the vaccination alone. In our previous clinical studies on patients with malignant gliomas, Bev was administered to 13 patients after VEGFRs vaccinations. One patient had a Grade 4 pulmonary embolism. Two patients had Grade 2 cerebral infarctions. There were no significant differences in the adverse event rates among patients treated with Bev, with the vaccination, or with Bev after the vaccination. Although careful observation is imperative for patients after this combination treatment strategy, VEGFRs-targeted vaccination may coexist with Bev for malignant gliomas.

LBA48 Clinical efficacy and immunity of combination therapy with nivolumab and IDO/PD-L1 peptide vaccine in patients with metastatic melanoma: A phase I/II trial

LBA48 Clinical efficacy and immunity of combination therapy with nivolumab and IDO/PD-L1 peptide vaccine in patients with metastatic melanoma: A phase I/II trial

Abstract 5578: Phase 1 study of XAGE1 peptide vaccine in patients with lung adenocarcinoma

Abstract Background: Lung adenocarcinomas show the highest proportion of approximately 70% among histologic types of non-small-cell lung cancer (NSCLC). Generally, lung adenocarcinomas have many passenger mutations in smokers and driver mutations such as EGFR and EML-ALK gene in non- or light smokers. On the other hand, NSCLC simultaneously expresses many cancer-testis (CT) antigens, which are expressed in cancer and normal testis tissues only. We previously reported that XAGE1 (81 amino acids) of a CT antigen is specifically expressed in approximately 40% to 60% of lung adenocarcinomas, and that it elicits spontaneous T cell and humoral immune responses in almost half of patients with XAGE1. In addition, lung adenocarcinomas with XAGE1 antigen and antibody (Ab) showed prolonged survival as compared with those of XAGE1-Ab-negative patients. Thus, XAGE1 is a major immunodominant antigen and play an important role in the immune surveillance of lung adenocarcinomas. Then, we for the first time conducted a phase 1 study of XAGE1 peptide vaccines in patients with lung adenocarcinoma. Patients and Methods: Two long-peptide vaccines of SLP1 and SLP2 were synthesized, and SLP1 and SLP2 were composed with 25-mer of XAGE1 peptide 6N~32Q and 44I~68H, respectively. The two peptide epitopes were considered to be recognized in both CD4 and CD8 T cell. The two peptide vaccines mixed with 0.2 KE Picibanil OK-432 of adjuvant and 1.25 ml Montanide ISA-51 were administered in advanced lung adenocarcinoma patients with XAGE1 antigen or Ab. Four doses of 500 micro-gram (level-1), 1 mg (level-2), and 2 mg (level-3) each were subcutaneously administered every two weeks. Primary and secondary endpoint of this study were safety and XAGE1-specific immune responses, respectively. Results: A total of ten patients was enrolled into this study, which was consisted of each three in level-1 and level-3 and four in level-2. The study was completed in 7 out of 10 patients, and three were dropped due to disease progression. Thirty-four adverse events related to vaccines were observed but not serious (grade 1 or 2); 9 skin induration, 6 fever, 4 local pain at injection, and so on. Before the vaccination, seven patients were positive for XAGE1-Ab, and three were negative. After the vaccination, the Ab titers were increased in five of seven XAGE1-Ab-positive patients, and one of three XAGE1-Ab-negative patients showed seropositive. Clinically, tumor marker CEA was decreased in two patients after the vaccination. On the other hand, CD4 T cells were isolated from one patient 12 weeks after the vaccination, and were stimulated in vitro by SLP1, SLP2, and the mixture with SLP1 and SLP2. The highest level of IFN-gamma secretion was observed in the mixture than those in SLP1 and SLP2 alone. Conclusions: This study shows that our XAGE1 peptide vaccine was well tolerated and elicited humoral and CD4 T cell responses in immunized patients. Citation Format: Mikio Oka, Koji Kurose, Naoya Yasogawa, Takaaki Yamaoka, Yoshihiro Ohue, Toru Oga. Phase 1 study of XAGE1 peptide vaccine in patients with lung adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5578.

Identification of two distinct populations of WT1-specific cytotoxic T lymphocytes in co-vaccination of WT1 killer and helper peptides.

Simultaneous induction of tumor antigen-specific cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) is required for an optimal anti-tumor immune response. WT1332, a 16-mer WT1-derived helper peptide, induce HTLs in an HLA class II-restricted manner and enhance the induction of WT1-specific CTLs in vitro. However, in vivo immune reaction to WT1332 vaccination in tumor-bearing patients remained unclear. Here, a striking difference in WT1-specific T cell responses was shown between WT1 CTL + WT1 helper peptide and WT1 CTL peptide vaccines in patients with recurrent glioma. WT1-specific CTLs were more strongly induced in the patients who were immunized with WT1 CTL + WT1 helper peptide vaccine, compared to those who were immunized with WT1 CTL vaccine alone. Importantly, a clear correlation was demonstrated between WT1-specific CTL and WT1332-specific HTL responses. Interestingly, two novel distinct populations of WT1-tetramerlow WT1-TCRlow CD5low and WT1-tetramerhigh WT1-TCRhigh CD5high CTLs were dominantly detected in WT1 CTL + WT1 helper peptide vaccine. Although natural WT1 peptide-reactive CTLs in the latter population were evidently less than those in the former population, the latter population showed natural WT1 peptide-specific proliferation capacity comparable to the former population, suggesting that the latter population highly expressing CD5, a marker of resistance to activation-induced cell death, should strongly expand and persist for a long time in patients. These results demonstrated the advantage of WT1 helper peptide vaccine for the enhancement of WT1-specific CTL induction by WT1 CTL peptide vaccine.

Clinical and histopathological analyses of VEGF receptors peptide vaccine in patients with primary glioblastoma - a case series

BackgroundThe expression of vascular endothelial growth factor (VEGF)-A/ VAGF receptors (VEGFRs) signaling plays a pivotal role in the tumor angiogenesis and the development of the immunosuppressive tumor microenvironment in glioblastomas. We have previously conducted exploratory clinical studies investigating VEGFRs peptide vaccination with and without multiple glioma oncoantigens in patients with recurrent high-grade gliomas. Recently, an exploratory clinical investigation of VEGFRs peptide vaccination was conducted in patients with progressive neurofibromatosis type 2. Those studies suggested that cytotoxic T lymphocytes (CTLs) induced by the vaccination can directly kill a wide variety of cells associated with tumor growth, including tumor vessels, tumor cells, and immunosuppressive cells expressing VEGFR1 and/or 2. In the present study, synergistic activity of the combination of VEGFRs peptide vaccination with chemotherapy was evaluated.MethodsWe performed the first clinical trial to assess VEGFR1 and 2 vaccination along with temozolomide (TMZ) -based chemoradiotherapy for the patients with primary glioblastomas. Furthermore, histopathological changes after the vaccination were evaluated using paired pre- and post- vaccination specimens.ResultsThe disappearance of radiographically enhanced lesion was observed in 2 patients after the vaccination, including one in which the methylation of the O6-methylguanine-DNA methyltransferase (MGMT) promoter was not observed. The histopathological findings of pre- and post-vaccination specimens demonstrated that tumor vessels showed negative or slight VEGFRs expressions after the vaccination and most endothelial cells were covered with PDGFR-β-positive pericytes. Notably, CTLs induced by VEGFRs peptide vaccination attacked not only tumor vessels but also tumor cells and regulatory T cells expressing VEGFRs even in recurrent tumors.ConclusionsVEGFR1 and 2 vaccination may have a preliminary synergistic effect when administered with TMZ. The limitation of the present study was the paucity of the number of the samples. Further studies involving more patients are warranted to confirm the findings of this study.Trial registrationThis study was registered as UMIN000013381 (University Hospital Medical Information Network-Clinical Trial Registry: UMIN-CTR) on 5 March, 2014 and with the Japan Registry of Clinical Trials (jRCT) as jRCTs031180170 on 1 March, 2019.

Abstract P5-04-21: Analysis of serum immune biomarkers for response to therapeutic personalized peptide vaccination in patients with metastatic breast cancer

Abstract Purpose: Our results from the previous clinical trials using personalized peptide vaccines (PPV) combined conventional chemo-hormonal therapies have confirmed the potential for clinical benefit in patients who had higher IgG antibody and/or CTL response to the immunized PPV (SABCS 2018 U Toh etc.). The aim of this study is to evaluate the association between the serum immunologic factors including cytokines, haptoglobin (HP), B-cell activating factor (BAFF) etc. and the clinical outcome of patients(pt) with metastatic breast cancer (mBC) who treated by personalized peptide vaccines (PPV). Methods: Peripheral blood samples from 57 pts and 52 pts obtained before and after the vaccination of PPV, respectively. Serum HP and IL-6 were analyzed by ELISA(R&D Systems, Life Technologies)and bead-based multiplex assays(Luminex 200 system)were performed for GM-CSF,IFN-γ,TNF-α, BAFF, TGF-β, IFNγ-induced protein 10(IP-10), IL-1β, IL-2,-4,-5,-8, -10. The association between each factor and clinical outcome was statistically evaluated. Results: Pt’s group (n=28) with low BAFF and high HP level (>544 pg/ml), high IFN-γ and high HP level or low IL-8 and high HP level before PPV treatment showed a significantly shorter median survival time (MST; p=0.015;0.068;0.002, respectively). There was no difference in high BAFF, low IFN-γ or high IL-8 level group(n=29). In contrast, pt’s group with low serum level of IL-10, GM-CSF, IL-5, IL-4 and low HP level (<544 pg/ml MV) after PPV treatment associated with significantly shorter MST (p=0.002; 0.001; 0.001; <0.001, respectively). Conclusions: The combination of serum levels of HP and BAFF, IFN-γ or cytokines of IL-8, -10, - 5, -4 might be useful prognostic biomarkers for mBC pts receiving PPV therapy. Citation Format: Uhi Toh, Shuko Saku, Yuko Takao, Sayaka Sakurai, Miki Takenaka, Shigeki Shichijo, Kyogo Itoh, Yoshito Akagi. Analysis of serum immune biomarkers for response to therapeutic personalized peptide vaccination in patients with metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-04-21.

A VEGF receptor vaccine demonstrates preliminary efficacy in neurofibromatosis type 2

The anti-VEGF antibody bevacizumab has shown efficacy for the treatment of neurofibromatosis type 2 (NF2). Theoretically, vascular endothelial growth factor receptors (VEGFRs)-specific cytotoxic T lymphocytes (CTLs) can kill both tumor vessel cells and tumor cells expressing VEGFRs. Here we show an exploratory clinical study of VEGFRs peptide vaccine in seven patients with progressive NF2-derived schwannomas. Hearing improves in 2/5 assessable patients (40%) as determined by international guidelines, with increases in word recognition scores. Tumor volume reductions of ≥20% are observed in two patients, including one in which bevacizumab had not been effective. There are no severe adverse events related to the vaccine. Both VEGFR1-specific and VEGFR2-specific CTLs are induced in six patients. Surgery is performed after vaccination in two patients, and significant reductions in the expression of VEGFRs in schwannomas are observed. Therefore, this clinical immunotherapy study demonstrates the safety and preliminary efficacy of VEGFRs peptide vaccination in patients with NF2.

VEGF Receptors Peptide Vaccine in Neurofibromatosis Type 2: A Single-Arm, Open-Label, Phase 1/2 Trial

Background: There is no established therapy for neurofibromatosis type 2 (NF2). Bevacizumab has recently proved efficacious for the treatment of NF2, presumably because vascular endothelial growth factor (VEGF) is essential for NF2 tumor growth. Theoretically, VEGF receptors (VEGFRs)-specific cytotoxic T lymphocytes (CTLs) can kill both tumor vessel cells and tumor cells expressing VEGFRs. The aim of the current study was to evaluate the safety and efficacy of a VEGFRs peptide vaccine in NF2 patients. Methods: An exploratory clinical study of VEGFRs peptide vaccine was conducted in 7 patients with progressive NF2-derived schwannomas. Tumor volume and blood flow were analyzed via magnetic resonance imaging and computed tomography perfusion, and hearing was evaluated via word recognition scores (WRSs) and pure-tone audiograms. To investigate the therapeutic mechanisms involved in this novel therapy, CTL responses and VEGFRs expression in schwannomas were analyzed. Findings: Hearing improved in 3 of the 6 assessable patients (50%), with WRS increases of more than 10%. Reductions of > 20% in more than one tumor were observed in 2 patients, including a case in which bevacizumab had not been effective (case 6). There were no severe adverse events related to the vaccine. Both VEGFR1 specific and VEGFR2-specific CTLs were induced in 6 patients, and in the remaining patient VEGFR1-specific CTLs were induced. Histological analysis of schwannomas revealed high VEGFRs expression both in tumor vessels and in tumor cells. Surgery was performed after vaccination in two patients, and significant reductions in VEGFRs expression in schwannomas were observed. Interpretation: This is the first clinical immunotherapy study demonstrating the safety and efficacy of VEGFRs peptide vaccination in patients with NF2. Trial Registration Number: The trial was registered at UMIN (UMI23565). Funding Statement: The authors state: None. Declaration of Interests: The authors have no personal financial or institutional interests in any of the drugs, materials, or devices mentioned in this article. Ethics Approval Statement: All protocols were approved by the Keio University Ethics Committee, and conducted in accordance with the Helsinki declaration on experimentation on human subjects.

Abstract P4-06-06: Comparison of the immunological and clinical effect of personalized peptide vaccination for patients with breast cancer

Abstract Background: Selected therapeutic personalized peptide vaccines (PPV) were effective for boosting anticancer immune response that was associated with the clinical outcome as a prognostic factor for metastatic recurrent breast cancer (mrBC) 1-2. In this study, we investigated the immunological and clinical effect of PPV as the prophylactic cancer vaccine for non-recurrent but high-risk BC (nrhrBC) patients (pts), and we compared it's features to those of the mrBC pts who had active cancers or became resistant to the standard therapies(TR-mrBC). Methods: Material and Patient eligibility criteria: The peptides were selected from the 31 PPVs according to the results of HLA typing and peptide-specific IgG titers. Pts with a histological diagnosis of BC and their HLA-A molecules should be each of -A2, A3, A11, A24, A26, A31 or A33. The clinical protocols were approved by the institutional review board. (UMIN000003081and 00000184400000). Treatment schedule: A maximum of 4 peptides was administrated as weekly for initial four vaccinations and as biweekly for further inoculations. The concomitant standard endocrine therapy and the chemo-endocrine therapy were available for nrhrBC pts after finishing the standard adjuvant chemotherapy, and for mrBC pts concurrently. Immune and clinical response assessment: Specific T-cell responses, IgG titers and cytokines were evaluated using by interferon (IFN)-γ ELISPOT, Luminex assay and ELISA system in every 6-8 vaccinations. Toxicity, clinical response and correlation with the immune responses were investigated. Results: 16 pts with nrhrBC, 41 pts with mrBC and 79 pts with TR-mrBC received median 18, 16 and 14 vaccines, respectively. After PPV therapies, peptide-specific IgG and CTLs increased significantly in a total of 47 (77%) and 37(60%) in nrhrBC pts, 102 (63%) and 98 (61%) in mrBC pts, and 150(53%) and 100 (42%) in TR-mrBC pts. Pts experienced Grade 1-3 skin reaction at injection site, no other grade 3 or 4 SAEs were associated with PPV but with the disease progression or combination therapy. The median time to progression (TTP) and overall survival (OS) were not reached in nrhrBC pts, 7.8 and 29 months in mrBC pts, and were 7.5 and 15.9 months in TR-mrBC pts, respectively. The peptide specific CTL response was correlated significantly with OS in nrhrBC pts and the IgG levels were associated with the better OS in either non TR-mrBC pts or TR-mrBC pts. High levels of IL-6, GM-CSF, IFN-g, IL-2 receptor, BAFF were associated with worse prognosis for pts with TR-mrBC. And high levels of GM-CSF and BAFF were associated with worse prognosis for pts with nrhrBC and mrBC, respectively. In contrast, High levels of IL-2 were associated with the better prognosis for pts with mrBC. Conclusion: This study indicated that immunological features of these three groups were different from each other with most potent PPV-induced immune boosting for nrhrBC pts. Pts with mrBC who had lower immune-suppressive cytokine levels had the better prognosis. These results suggested the PPV therapy could be effective for postoperative prophylactic vaccination in patients with nrhrBC.

Abstract A017: Immunologic efficacy of heat shock protein 105 peptide vaccine in patients with advanced colorectal and esophageal cancer

Abstract Purpose: Heat shock protein 105 (HSP105) is overexpressed in a variety of human cancers, including colorectal cancer (CRC) and esophageal cancer (EC). We identified HLA-A24 or A2-restricted HSP105 peptides that can induce HSP105 peptide-specific cytotoxic T lymphocytes (CTLs) (EP1536006, JP5112615, JP5291641, US9,404,925) and curried out a phase I clinical trial of HLA-A24 or A2-restricted HSP105 peptide vaccine in patients with CRC or EC (UMIN ID000017809). In this study, we aimed to demonstrate the immunological efficacy of the novel vaccine. Experimental design: 30 patients (HLA-A24 group; 15 patients, HLA-A2 group; 15 patients) with advanced CRC or EC were enrolled. Two types of vaccine (A24-1 and A24-7 or A2-7 and A2-12) were administered into the patients, matching HLA-types. Immunological responses were analyzed by ex vivo and in vitro IFN-γ ELISPOT assay using peripheral blood mononuclear cells before and after vaccination, and cytokines produced by HSP105-specific CTLs were measured by Cytometric Bead Array assay. We also analyzed the correlation between immunological responses and prognosis. Result: HSP105 peptide vaccines induced HSP105 peptide-specific CTLs in 15 of 30 patients. In HLA-A24 group, there were 7 patients with the induction only in ex vivo and almost all patients (n=13) showed skin reactions of vaccine sites. By contrast, in HLA-A2 group, there were 4 patients with the induction in ex vivo and 6 patients in in vitro, respectively, and only 6 patients with skin reactions of vaccine sites. In all patients, the existence of skin reaction correlated with the induction in ex vivo (p<0.01). The progression-free survival (PFS) and overall survival (OS) were significantly longer in patients with the induction (n=15) than in those without (n=15) (P<0.01, respectively). The peptide-specific CTL frequency correlated with OS and could be a predictive marker of PFS and OS. Furthermore, HSP105 peptide-specific cytokine production was observed in various tissues of 8 patients, such as vaccine injected sites skins, metastatic and primary tumors. It suggested that HSP105-specific CTLs not only accumulated at injected sites but also infiltrated into tumor tissues. Additionally, we succeeded in establishing two types of highly functional HSP105 peptide-specific CTL clones and sequenced the T-cell receptors (TCRs) of these clones. Conclusion: Our results suggested that HSP105 peptide vaccine could improve the prognosis of patients with advanced CRC and EC by inducing the antitumor immune responses. To further extend the efficacy, we are developing TCR-engineered T-cell therapy using TCR sequences obtained from HSP105 peptide-specific CTL clones and intratumoral injection method of this vaccine. Citation Format: Yasuhiro Shimizu, Toshiaki Yoshikawa, Kojima Takashi, Kayoko Shoda, Kazuto Nosaka, Shoichi Mizuno, Satoshi Wada, Yuki Fujimoto, Tetsuro Sasada, Kenichi Kohashi, Hideaki Bando, Itaru Endo, Tetsuya Nakatsura. Immunologic efficacy of heat shock protein 105 peptide vaccine in patients with advanced colorectal and esophageal cancer [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A017.

Antibody-based Delivery of TNF to the Tumor Neovasculature Potentiates the Therapeutic Activity of a Peptide Anticancer Vaccine.

There is a growing interest in the use of tumor antigens for therapeutic vaccination strategies. Unfortunately, in most cases, the use of peptide vaccines in patients does not mediate shrinkage of solid tumor masses.Experimental Design: Here, we studied the opportunity to boost peptide vaccination with F8-TNF, an antibody fusion protein that selectively delivers TNF to the tumor extracellular matrix. AH1, a model antigen to investigate CD8+ T-cell immunity in BALB/c mice, was used as vaccine. Peptide antigens alone exhibited only a modest tumor growth inhibition. However, anticancer activity could be substantially increased by combination with F8-TNF. Analysis of T cells in tumors and in draining lymph nodes revealed a dramatic expansion of AH1-specific CD8+ T cells, which were strongly positive for PD-1, LAG-3, and TIM-3. The synergistic anticancer activity, observed in the combined use of peptide vaccination and F8-TNF, was largely due to the ability of the fusion protein to induce a rapid hemorrhagic necrosis in the tumor mass, thus leaving few residual tumor cells. While the cell surface phenotype of tumor-infiltrating CD8+ T cells did not substantially change upon treatment, the proportion of AH1-specific T cells was strongly increased in the combination therapy group, reaching more than 50% of the CD8+ T cells within the tumor mass. Because both peptide vaccination strategies and tumor-homing TNF fusion proteins are currently being studied in clinical trials, our study provides a rationale for the combination of these 2 regimens for the treatment of patients with cancer.

OS2.2 Highly personalized peptide vaccination for patients with newly diagnosed glioblastoma: the GAPVAC trial

OS2.2 Highly personalized peptide vaccination for patients with newly diagnosed glioblastoma: the GAPVAC trial

Abstract P3-05-09: Prognostic factors for therapeutic personalized peptide vaccines in patients with metastatic recurrent breast cancer

Abstract Background: We have previously reported the prognostic role of humoral antigen spreading response against prostate-related antigen (PRA) for metastatic recurrent breast cancer (mrBC) patients who received personalized peptide vaccine (PPV) therapy (Toh U, SABCS 2015). The prognostic effect was additionally evaluated by the clinical relevant factors including intrinsic subtype, the regimens of combined chemo-hormonal therapies in present study. Methods:We analyzed serum IgG responses to all of the peptide candidates included PRAs (PSA, PAP and PMSA) after PPV therapy by the Luminex systemusing peripheral blood samples from 77 vaccinated mrBC patients. The clinical factors and relevant events were statistically evaluated. Results: After 6 and 12cycles of PPV therapy, the serum IgG of anti-PSA, anti-PAP, and/or anti-PMSA increased significantly in 31 patients (PRA response group), and the median progression free survival (PFS) and median overall survival (OS) were 8.1 and 14.3 months, but were 5.1 and 10.8 months, respectively, in the remaining 46 patients with no anti-PRA IgG response (PRA non-response Group). The anti-PRA IgG level was marginally correlated withPFS (p=0.059) and OS (p=0.082) between these two groups, which was a significant prognostic factor for PFS (Log-rank: 0.009) in estrogen-positive cancer patients (ER+). The statistical analyses showed that the clinical outcome was in favor of > 60 year-old patients, those with longer PPV therapies (>3 months), and those who received combined standard hormonal therapies or bisphosphonate/anti-RANKL therapy. Conclusions: This study indicated a clinical significance between the pre-and post- PPV therapy measurement of serum anti-PRA IgG in patients with mrBC, which may be a useful prognostic marker for monitoring peptide vaccine treatment outcomes, particularly for patients > 60 years with ER+ breast cancer. These results also suggest that the immunotherapeutic peptide vaccine could be efficiently combined with hormonal therapy, anti-HER2 therapy, and bisphosphonate/anti-RANKL therapy in mrBC patients. Citation Format: Toh U, Saku S, Iwakuma N, Takao Y, Okabe M, Akashi M, Yamada A, Shichijo S, Itoh K, Akagi Y. Prognostic factors for therapeutic personalized peptide vaccines in patients with metastatic recurrent breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-09.

Immunological efficacy of glypican-3 peptide vaccine in patients with advanced hepatocellular carcinoma

ABSTRACTWe have previously conducted a phase I trial to test the efficacy of a glypican-3 (GPC3) peptide vaccine in patients with advanced hepatocellular carcinoma (HCC); however, its immunological mechanism of action remains unclear. Here, we report a pilot study conducted to evaluate the immunological mechanisms of action of this GPC3 peptide vaccine (UMIN-CTR number 000005093). Eleven patients with advanced HCC were vaccinated with the GPC3 peptide in this trial. The primary end point was GPC3 peptide-specific immune response induced by the GPC3 peptide vaccination. The secondary endpoints were clinical and biologic outcomes. We demonstrated that the present vaccine induced GPC3 peptide-specific cytotoxic T lymphocytes (CTLs), which were found to infiltrate into the tumor. Moreover, we established GPC3 peptide-specific CTL clones from a biopsy specimen: these cells exhibited GPC3 peptide-specific cytokine secretion and cell cytotoxicity. The plasma GPC3 level tended to decrease temporarily at least once during the follow-up period. The GPC3-specific CTL frequency after vaccination was correlated with overall survival. The degree of skin reactions at the injection site correlated with the GPC3 peptide-specific CTLs. Furthermore, we sequenced the T cell receptors (TCRs) of tumor-infiltrating lymphocyte (TIL) clones, and confirmed the existence of this TCR repertoire in both tumor tissue and PBMCs. In response to these data, we are developing TCR-engineered T cell therapy using TCR sequences obtained from GPC3 peptide-specific CTL clones for improved efficacy in patients with advanced HCC.