548 CD8+ tissue-resident memory T cells are tumour reactive and increase after immunotherapy in a case of metastatic mucosal melanoma

Angela Pizzolla, Simon Keam, Ismael Vergara, Franco Caramia, Minyu Wang, Nikolce Kocovski, ThuNgoc Nguyen, Sean Macdonald, Daniela Tantalo, Pasquale Petrone, Han Xian Aw Yeang, David Gyorki (+7 others)
2020 Journal for ImmunoTherapy of Cancer  
BackgroundMucosal melanoma is a rare subtype of melanoma originating from mucosal tissues (1), metastases are very aggressive and respond poorly to therapy, including immune checkpoint inhibitors (ICI) such as anti-CTLA4 and anti-PD1 antibodies (2–5). CD8+ T cells constitute the most abundant immune infiltrate in metastatic melanoma, of which the Tissue Resident Memory subset (TRM) is of particular interest (6). CD8+ TRM cells express the highest levels of immune checkpoint receptors,
more » ... eceptors, proliferate in response to ICI and correlate with longer disease-free and overall survival (6–8). The immune landscape in mucosal melanoma remains poorly characterized. We aimed to: 1) phenotype CD8+ T cells and TRM infiltrating metastatic mucosal melanoma, 2) characterize the clonality of TRM in relation to other CD8+ T cell subsets and 3) define the capacity of CD8+ T cells and TRM to respond to melanoma cells and to in vivo and in vitro anti-PD1 treatment.MethodsWe investigated the CD8+ T and TRM cells infiltrating two temporally- and spatially-distant subcutaneous metastases, these originated from a primary vaginal mucosal melanoma. One metastasis was excised prior to anti-PD1 treatment and one was anti-PD1 refractory, having progressed on treatment. We used mass cytometry and single-cell RNA and TCR sequencing to characterise the phenotype and clonality of the T cells, multiplex immunohistochemistry to define their spatial relationship with tumour cells and other T cells, and functional assays to determine TRM response to tumour cells (figure 1).ResultsCD8+ TRM frequency increased with time and anti-PD1 treatment, forming clusters at the tumour margin. T cells in the anti-PD1 refractory lesion were more activated than T cells in the first tumour and were bound by anti-PD1 antibody in vivo. T cells could not be stimulated by anti-PD1 directly ex vivo. Both metastatic lesions shared common T cell clusters including TRM. Furthermore, TRM in each tumour shared T cell clones, suggesting the presence of common antigens between metastatic sites. Indeed, the two metastases had a similar mutational profile. In vitro expanded tumour infiltrating lymphocytes from both lesions recognized tumour cells from both lesions and the same neoantigen generated from a single point mutation in the gene CDKN1C. Finally, tumour cells stimulated TRM cells more robustly than other T cells subsets.Abstract 548 Figure 1Graphical depiction of the methods used to characterise T cells in mucosal metastatic melanomaConclusionsIn this patient with vaginal mucosal melanoma, subsequent melanoma metastases of clonal origin attracted CD8+ T cells of similar specificity, among which TRM cells responded more vigorously to tumour cells than other T cells subsets.AcknowledgementsThe authors would like to acknowledge imCORE La Hoffmann- Roche Ltd. for funding.Ethics ApprovalPatients diagnosed with stage 3 or 4 metastatic melanoma and undergoing clinically indicated surgery were enrolled in prospective studies approved by the Peter MacCallum Cancer Centre human ethics research committee (13/141). All experimental protocols have been approved and clinical data has been collected prospectively.ReferencesCarvajal RD, Hamid O, Ariyan C. Mucosal Melanoma. [cited 2020 Apr 1]; Available from: https://www.uptodate.com/contents/mucosal-melanomaDel Vecchio M, Di Guardo L, Ascierto PA, Grimaldi AM, Sileni VC, Pigozzo J, et al. Efficacy and safety of ipilimumab 3 mg/kg in patients with pretreated, metastatic, mucosal melanoma. Eur J Cancer Oxf Engl 1990; 2014 Jan;50(1):121–7.Postow MA, Luke JJ, Bluth MJ, Ramaiya N, Panageas KS, Lawrence DP, et al. Ipilimumab for patients with advanced mucosal melanoma. The Oncologist 2013 Jun;18(6):726–32.D'Angelo SP, Larkin J, Sosman JA, Lebbé C, Brady B, Neyns B, et al. Efficacy and safety of nivolumab alone or in combination with ipilimumab in patients with mucosal melanoma: a pooled analysis. J Clin Oncol Off J Am Soc Clin Oncol. 2017 Jan 10;35(2):226–35.Hamid O, Robert C, Ribas A, Hodi FS, Walpole E, Daud A, et al. Antitumour activity of pembrolizumab in advanced mucosal melanoma: a post-hoc analysis of KEYNOTE-001, 002, 006. Br J Cancer 2018;119(6):670–4.Boddupalli CS, Bar N, Kadaveru K, Krauthammer M, Pornputtapong N, Mai Z, et al. Interlesional diversity of T cell receptors in melanoma with immune checkpoints enriched in tissue-resident memory T cells. JCI Insight [Internet]. 2016 Dec 22 [cited 2019 Apr 24];1(21). Available from: https://insight.jci.org/articles/view/88955Edwards J, Wilmott JS, Madore J, Gide TN, Quek C, Tasker A, et al. CD103+ Tumor-resident CD8+ T cells are associated with improved survival in immunotherapy-naïve melanoma patients and expand significantly during anti-PD-1 treatment. Clin Cancer Res Off J Am Assoc Cancer Res 2018 Jul 1;24(13):3036–45.Savas P, Virassamy B, Ye C, Salim A, Mintoff CP, Caramia F, et al. Single-cell profiling of breast cancer T cells reveals a tissue-resident memory subset associated with improved prognosis. Nat Med 2018 Jul;24(7):986–93.
doi:10.1136/jitc-2020-sitc2020.0548 fatcat:d53gdarcjvfnrca3zgpaf4gnka