CRI-CIMT-EATI-AACR INTERNATIONALCANCER IMMUNOTHERAPY CONFERENCE
TRANSLATING SCIENCE INTO SURVIVALSEPTEMBER 25th to 28th, 2019 - PARIS

Abstracts
BOOK

www.cancerimmunotherapyconference.org

SESSION B
Keywords : ribosome profiling, neoantigen, Ribo-seq.
References :Ji, Z., Song, R., Regev, A., and Struhl, K. (2015). Many lncRNAs, 5’UTRs, and pseudogenes
are translated and some are likely to express functional proteins. eLife 4. Keskin, D.B.,
et al. (2019). Neoantigen vaccine generates intratumoral T cell responses in phase Ibglioblastoma trial. Nature 565, 234-239. Ott, P.A., et al. (2017). An immunogenic personal neoantigen vaccine for patients with melanoma. Nature 547, 217–221. Erhard, F.,et al. (2018). Improved Ribo-seq enables identification of cryptic translation events. Nat
Methods 15 :363-366.

B169 / Neoantigen prediction for cancer vaccine acrossentities
Zhiqin HUANG (German Cancer Research Center), Iris Kaiser (National Center for Tumor Diseases (NCT) Heidelberg and Heidelberg University Hospital Germany), Jutta Funk (National Centerfor Tumor Diseases (NCT) Heidelberg and Heidelberg UniversityHospital Germany), Evgeniya Denisova (German Cancer ResearchCenter (DKFZ), Heidelberg, Germany), Benedikt Brors (GermanCancer Research Center (DKFZ), Heidelberg, Germany), Niels
Halama (National Center for Tumor Diseases (NCT) Heidelberg,Heidelberg University Hospital , German Cancer Research Center(DKFZ), Heidelberg, Germany), Stefan Fröhling (National Center
for Tumor Diseases (NCT) Heidelberg, German Cancer ResearchCenter (DKFZ), Heidelberg, Germany), Inka Zörnig (National Center for Tumor Diseases (NCT) Heidelberg and Heidelberg University Hospital Germany), Dirk Jäger (National Center for Tumor
Diseases (NCT) Heidelberg, Heidelberg University Hospital , German Cancer Research Center (DKFZ), Heidelberg, Germany).
Different strategies of cancer immunotherapy have shown outstanding success in a number of patients across various tumor
types. Cancer genome-based identification of patient-specificneoantigens plays an important role in cancer immunotherapy,e.g. vaccine strategies. The expression of neoantigens by tumor
cells allows the immune system to distinguish cancer cells fromnormal cells and, potentially leads to activation of the patient’s
own immune effector cells to specifically eradicate tumor cells.
However, only a small fraction of genomic mutations may leadto immunogenic neoantigens and thus a reliable prediction ofimmunogenic neoantigens is required. We developed a pipeline
to determine the patient´s HLA type and to predict MHC class
I and II neoantigens based on the analysis of the next-generation sequencing data. Our pipeline is able to predict neoantigens
from nonsynonymous mutations, small insertions/deletions andgene fusions, and has already been successfully applied to predict
neoepitopes in various cancer patients. Among 24 vaccinated neopeptides, more than 80% can either expand pre-existing T-cellresponses or induce new T-cell specificities after vaccinationin cancer patients (n=4) across tumor entities. Importantly, wedemonstrate that neopeptides arising from fusion genes can also
induce T-cell responses. Currently, this pipeline is being optimized
and further experimental validation is conducted to identify which
fusion-derived neoepitopes among the vaccinated neopeptides
can stimulate T cell responses. Perceptively, we aim to efficiently translate the neoantigen-based strategy to clinical application,e.g. TCR-specific engineered T-cell therapy.
Keywords : Neoantigen, Fusion, Immunotherapy, Cancer vaccine.
References :Koşaloğlu, Z., Zörnig, I., Halama, N., Kaiser, I., Buchhalter, I., Grabe, N.... & Jäger, D. (2016).
Identification of immunotherapeutic targets by genomic profiling of rectal NET metastases. Oncoimmunology, 5(11), e1213931.

B170 / HLA ligandome analysis reveals an antigen processing signature required for HLA class I presentation andCD8+ T cell responses
Takayuki Kanaseki (Sapporo Medical University), Ayumi Hongo(Sapporo Medical University), Serina Tokita (Sapporo Dohto Hospital), Toshihiko Torigoe (Sapporo Medical University).

tein sequences flanking the ligands revealed that the frequencyof proline at amino acid positions 1-3 upstream of the ligands
was selectively decreased. The depleted proline signature was
the strongest among all the upstream and downstream profiles.
Experiments using live cells demonstrated that the presence ofproline at upstream positions 1-3 attenuated CD8+ T cell responses against a model cancer antigen. Other experiments in whichN-terminally flanking antigen precursors were confined in the ER
demonstrated an inability to remove upstream prolines regardless of their positions, suggesting a need for synergistic action
across cellular compartments for making the proline signature.
Our results highlight an antigen processing signature that could
affect HLA class I peptide repertoire formation and CD8+ T cell
responses.
Keywords : Tumor antigens.
References :J Immunol. 2019 May 15 ;202(10):2849-2855. doi : 10.4049/jimmunol.1900029.

B171 / Immunogenicity of HLA class II-restricted neoantigens derived from driver mutations
Tetsuro Sasada (Kanagawa Cancer Center), Susumu Iiizumi(Kanagawa Cancer Center), Taku Kouro (Kanagawa Cancer Center), Mamoru Kawahara (Kanagawa Cancer Center), Norihiro Nakamura (BrightPath Biotherapeutics Co., Ltd.).
Recently, increasing attention has been paid to neoantigens thatare derived from somatic genetic mutations specifically present
in cancer cells. Since they can be recognized as non-self by theimmune system, they are expected to induce stronger immune responses than non-mutated self-antigens. In particular, since “driver mutations” that are directly involved in malignant processes arefrequently shared by patients with various types of cancers anddo not disappear easily by immune escape, they could represent
appropriate off-the-shelf targets for cancer immunotherapy.
In the current study, we evaluated the immunogenicity of 10
well-known driver mutations, including KRAS-G12D, KRAS-G12V,
KRAS-G12C, KRAS-G12R, KRAS-G13D, NRAS-Q61K, NRAS-Q61R,PIK3CA-E545K, PIK3CA-H1047R, and C-Kit-D816V, which arefrequently expressed in various cancers using peripheral bloodmononuclear cells from healthy donors (n = 25). Of the 10 synthetic peptides (27 mer) derived from these mutations, the six
peptides from KRAS-G12D, KRAS-G12R, KRAS-G13D, NRAS-Q61R,PIK3CA-H1047R, and C-Kit-D816V induced T cell responses. In
particular, more than 10% of the donors showed immune responses to PIK3CA-H1047R, C-Kit-D816V, KRAS-G13D, and NRAS-Q61R.
All six peptides induced HLA class II-restricted CD4+ T cell responses ; notably, PIK3CA-H1047R contained at least two different
CD4+ T cell epitopes restricted to different HLA class II alleles. Inaddition, PIK3CA-H1047R and C-Kit-D816V induced antigen-specific CD8+ T cells as well, indicating that they might contain both
HLA class I- and class II-restricted epitopes.
Our findings suggested that frequent driver mutations are notalways less immunogenic, since six of 10 well-known driver mutations induced specific T cell responses. Since the identified neoantigens might be shared by patients with various types of cancers, they have the potential to be promising off-the-shelf cancer
immunotherapy targets in patients with the corresponding mutations.
Keywords : neoantigen, driver mutation, HLA class II.
References :Iiizumi S, Ohtake J, Murakami N, Kouro T, Kawahara M, Isoda F, Hamana H, Kishi H,Nakamura N, Sasada T. Identification of Novel HLA Class II-Restricted Neoantigens Derived from Driver Mutations. Cancers (Basel). 2019 Feb 24 ;11(2). pii : E266. doi : 10.3390/
cancers11020266.

CD8+ T cells recognize peptides displayed by HLA class I molecules, discriminating cancer cells. Difficulty in predicting HLAclass I ligands is attributed to the complexity of the antigen processing pathway across the cytosol and the endoplasmic reticulum (ER). Here, we captured natural HLA class I ligands displayedby multiple types of cancer cell lines using HLA ligandome analysis that employs mass spectrometry, and analyzed the imprintsof antigen processing. The comprehensive analysis of source-proFIFTH CRI-CIMT-EATI-AACR INTERNATIONAL CANCER IMMUNOTHERAPY CONFERENCESEPT. 25 - 28, 2019 - PARIS, FRANCE166