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Immunogenicity; Proteogenomics Inmunogenicidad; Proteogenómica Immunogenicitat; Proteogenòmica Purpose: Tumor antigens are central to antitumor immunity. Recent evidence suggests that peptides from noncanonical (nonC) aberrantly translated proteins can be presented on HLA-I by tumor cells. Here, we investigated the immunogenicity of nonC tumor HLA-I ligands (nonC-TL) to better understand their contribution to cancer immunosurveillance and their therapeutic applicability. Experimental Design: Peptides presented on HLA-I were identified in 9 patient-derived tumor cell lines from melanoma, gynecologic, and head and neck cancer through proteogenomics. A total of 507 candidate tumor antigens, including nonC-TL, neoantigens, cancer-germline, or melanocyte differentiation antigens, were tested for T-cell recognition of preexisting responses in patients with cancer. Donor peripheral blood lymphocytes (PBL) were in vitro sensitized against 170 selected nonC-TL to isolate antigen-specific T-cell receptors (TCR) and evaluate their therapeutic potential. Results: We found no recognition of the 507 nonC-TL tested by autologous ex vivo expanded tumor-reactive T-cell cultures while the same cultures demonstrated reactivity to mutated, cancer-germline, or melanocyte differentiation antigens. However, in vitro sensitization of donor PBL against 170 selected nonC-TL, led to the identification of TCRs specific to three nonC-TL, two of which mapped to the 5′ UTR regions of HOXC13 and ZKSCAN1, and one mapping to a noncoding spliced variant of C5orf22C. T cells targeting these nonC-TL recognized cancer cell lines naturally presenting their corresponding antigens. Expression of the three immunogenic nonC-TL was shared across tumor types and barely or not detected in normal cells. Conclusions: Our findings predict a limited contribution of nonC-TL to cancer immunosurveillance but demonstrate they may be attractive novel targets for widely applicable immunotherapies. We thank the patients for their participation in this study, Steven A. Rosenberg for providing valuable reagents and support for NGS studies, R. Pujol for helpful scientific discussion, J. Gonzalez for bioinformatics support, CRG/UPF Flow Cytometry Unit for assistance with cell sorting, and CRG/UPF and IRB Proteomics Units for technical support. A. Gros and this work were funded by the Comprehensive Program of Cancer Immunotherapy & Immunology II (CAIMI-II) supported by the BBVA Foundation (53/2021), Institute Carlos III (MS15/00058 and PI17/01085), AECC (IDEAS197PORT), and La Fundació La Marató de TV3 (201919–30). We thank CERCA Programme / Generalitat de Catalunya for institutional support. M. Lozano-Rabella was supported by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) (2018FI_B 00946). A. Garcia-Garijo was supported by Generalitat PERIS award (SLT017/20/000131). A. Yuste-Estevanez was supported by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) (2021 FI_B 00365). J. Palomero was supported by the Beatriu de Pinós programme (BP 2018), cofounded by the Agency for Management of University and Research Grants (AGAUR) and European Union's Horizon 2020.

Includes a large list of all the peptides and details of the HLA-I ligands identified at =30 ALC score

Supplementary Figure 1. Validation of HLA-I ligand tumor antigen candidates with synthetic peptides Supplementary Figure 2. Validation of selected HLA-I ligand tumor antigen candidates identified in Mel-1 and Mel-3 with isotope-labeled peptides Supplementary Figure 3. Frequency of nonC peptides detected in HLA-I. Supplementary Fig. 4. HLA-I allele binding motif of all patients included in the study. Supplementary Figure 5. A fraction of nonC-TL can be detected in publicly available immunopeptidomics datasets from human tumor biopsies Supplementary Figure 6. Evaluation of pre-existing T-cell responses to candidate tumor antigens in cancer patients Supplementary Figure 7. Enrichment of antigen-specific T cells from cancer patients by flow cytometry-based sorting. Supplementary Figure 8. Deconvolution of peptide pools containing recognized CGA or melanoma-associated antigens. Supplementary Figure 9. Functional avidity and specificity of neoantigen-specific T cells isolated from cancer patients. Supplementary Figure 10. HLA restriction element and recognition of autologous tumor cell lines by antigen-specific T cells isolated from cancer patients. SupplementaryFigure 11. Genomic location of the three immunogenic nonC-TL identified through IVS. Supplementary Figure 12. Recognition of the predicted ORFs encoding the immunogenic nonC-TL by TCR transduced cells. Supplementary Figure 13. Loss of recognition of TCL transfected with Cas9-sgRNA targeting the predicted 5’U-HOXC13 ORF. Supplementary Figure 14. Assessment of expression and translation of the immunogenic nonC-TL in human healthy cells. Supplementary Figure 15. NonC-TL are the main source of candidate tumor antigens identified by proteogenomics but tumor-reactive T cells preferentially recognize neoantigens derived from NSM.

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Background The Spanish Melanoma Group (GEM) developed a national registry of patients with melanoma infected by SARS-CoV-2 ( GRAVID ).Methods The main objective was to describe the COVID-19 fatality rate in patients with melanoma throughout the pandemic, as well as to explore the effect of melanoma treatment and tumor stage on the risk of COVID-19 complications. These are the final data of the register, including cases from February 2020 to September 2021.Results One hundred-fifty cases were registered. Median age was 68 years (range 6-95), 61 (40%) patients were females, and 63 (42%) patients had stage IV. Thirty-nine (26%) were on treatment with immunotherapy, and 17 (11%) with BRAF-MEK inhibitors. COVID-19 was resolved in 119 cases, including 85 (57%) patients cured, 15 (10%) that died due to melanoma, and 20 (13%) that died due to COVID-19. Only age over 60 years, cardiovascular disorders, and diabetes mellitus increased the risk of death due to COVID-19, but not advanced melanoma stage nor melanoma systemic therapies. Three waves have been covered by the register: February-May 2020, August-November 2020, and December 2020-April 2021. The first wave had the highest number of registered cases and COVID-19 mortality.Conclusion Tumor stage or melanoma treatments are non-significant prognostic factors for COVID-19 mortality. During the pandemic in Spain there was a downward trend in the number of patients registered across the waves, as well as in the severity of the infection.

Improved selection of cancer patients who are most likely to respond to immune checkpoint inhibitors remains an unmet clinical need. Recently, a positive correlation between levels of

Improved selection of cancer patients who are most likely to respond to immune checkpoint inhibitors remains an unmet clinical need. Recently, a positive correlation between levels of PD1 mRNA and clinical outcome in response to PD1 blockade across diverse tumor histologies has been confirmed in several datasets. ACROPOLI is a parallel cohort, non-randomized, phase II study that aims to evaluate the efficacy of the anti-PD1 immune checkpoint inhibitor spartalizumab as monotherapy in metastatic patients with solid tumors that express high levels of PD1 (cohort 1; n = 111). An additional cohort of 30 patients with tumors expressing low levels of PD1, where PD1/PD-L1 antibodies in monotherapy are standard treatment, will also be included (cohort 2). Primary end point is overall response rate in cohort 1. Considering previous data, we hypothesized that anti-PD1 monotherapy is effective across multiple cancer types in patients with PD1-high mRNA expressing tumors. Given these observations, ACROPOLI is a phase II study designed to study spartalizumab in this population. This article describes the SOLTI-1904 ACROPOLI phase II trial, `Efficacy of spartalizumab across multiple cancertypes in patients with PD1-highmRNA expressing tumors defined by a single and pre-specified cutoff.' The primary objective is to determine overall response rate (ORR) in the PD1-high population. Secondary objectives include other measures of clinical efficacy and evaluation of safety and tolerability. Spartalizumab has shown to have a manageable safety profile and preliminary clinical efficacy according to several phase I/II clinical trials [1-3].

Immunotherapy with immune checkpoint inhibitors (ICIs) have been reported to induce de novo or exacerbate pre-existing Myasthenia Gravis (MG). We present a single center case series of patients who developed an immune-related myasthenia gravis (irMG) related with ICIs. We performed a retrospective chart review of the electronic medical records between 1 September 2017 and 2022. We report the clinical features, presentation forms, diagnostic workflows, general management and outcomes of six patients who received ICIs for different solid organ malignancies and developed an irMG frequently overlapping with immune-related myocarditis and/or myositis. The aim of the article is to describe the clinical features, treatment and outcomes of this challenging and potentially life-threating syndrome, comparing our data with those described in the literature. Differences between irMG and classic MG are highlighted.

Background: There is a lack of predictive biomarkers for immunotherapy in melanoma. In terms of IHC, there is no strong rational to support the use of PD-L1 expression. BRAF mutations occur in 40-50% of melanomas and the MAPK pathway may also be activated by NRAS mutations. Patients harboring these mutations face usually a worse prognosis. BO-112 is a double stranded synthetic RNA formulated with polyethyleneimine (PEI) that, by mimicking the effect of a viral infection, mobilizes the immune system. Prior data from a phase I trial (NCT02828098) suggest that, when administered intratumorally, it causes an increase in CD8 infiltration and PD-L1 expression. The role of these and other biomarkers is being explored in the present phase II clinical trial. Study Design: Single arm study with BO-112 plus pembrolizumab (NCT04570332) in patients with advanced melanoma in progression to anti-PD1 therapy. Tumors were genotyped by next generation sequencing, whole exome sequencing and tumor mutation burden. Antitumor and immunological effects of the treatment in the tumor microenvironment were assessed by PDL1 and CD8 immunohistochemistry with a paired biopsy performed after 21 days of treatment. Results: A preliminary analysis has been performed, based on patients evaluable for clinical benefit (defined as response or stable disease>16 weeks). Samples from 35 patients have been analyzed, with 24 patients paired biopsies available. Patients with “cold” tumors (PD-L1 negative and CD8 low) at baseline had a trend to lack of clinical benefit. Only basal PD-L1 in the inflammatory component showed a statistically significant correlation with clinical outcome (4/20 (25%) tumors PDL1 IC negative had benefit versus 10/15 (67%) positive), p=0.0053. Fifteen patients had an increase in PD-L1 and 14 patients had increase in CD8 infiltrate after BO-112 treatment; the lack of increase in PDL1 and CD8 after treatment was also predictive of lack of response (p=0.04). BRAF/NRAS driver mutations correlated with positive outcome. Clinical benefit was observed in 4 of 17 (24%) patients not carrying activating mutations whereas 11 out of 18 (61%) patients with BRAF/NRAS activating mutations had clinical benefit (p=0.02), mainly in cutaneous histology (14% versus 65%, p=0.02). Mucosal melanoma patients (n=3) achieved an ORR 66.7% and DCR 100%. The two mucosal melanoma patients with partial response harbored SETD2 mutations and one of them showed extensive cyclic nucleotide-gated (CNGs), indicative of defects in DNA repair pathways. Regarding acral melanoma patients (n=9), no responses were observed, even in the single case with a NRAS mutation. The only patient achieving clinical benefit, with stable disease>16 weeks; had a unique mutation profile, with TP53 (inactivating) and KIT (activating) mutations. Conclusions: Patients basal mutant BRAF/NRAS could have more probability of benefit from BO-112 and pembrolizumab combination. PD-L1 and/or CD8 increase is an early marker of response. These findings could help to select patients in future clinical trials. Further investigation into predictive biomarkers is warranted. Citation Format: Ruth Roman, Philippe Saiag, Caroline Dutriaux, Luis de la Cruz Merino, Eduardo Castanon, Miguel F. Sanmamed, Caroline Robert, Juan F. Rodríguez-Moreno, Pablo Cerezuela-Fuentes, Ana M. Arance, María González Cao, Henry Montaudié, María Pilar López Criado, Julie Charles, Alfonso Berrocal, María del Carmen Álamo de la Gala, Enrique de Miguel, Elisa Funk-Brentano, Sorilla Prey, Eva Muñoz-Couselo, Delvys Rodríguez Abreu, Juan Martín-Liberal, Helena Escuin-Ordinas, Mark Branum, Sonia Macia, Marisol Quintero, Javier Sánchez López, Marya F. Chaney, Beatriz García-Peláez, Marta Vives-Usano, Miguel Ángel Molina, Stéphane Dalle, Iván Márquez-Rodas. Correlation of biomarkers and clinical benefit of intratumoral BO112 and pembrolizumab in patients with anti PD1 refractory melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT107.