Contribution of pre-existing neoantigen-specific T cells to a durable complete response after tumor-pulsed dendritic cell vaccine plus nivolumab therapy in a patient with metastatic salivary duct carcinoma

In this study, we reported a case of refractory metastatic SDC that was treated with a tumor lysate-pulsed DC vaccine followed by a single injection of low-dose nivolumab, and a durable complete response was achieved. We retrospectively analyzed the immunological factors that contributed to these long-lasting clinical effects. First, we performed neoantigen analysis using resected metastatic tumor specimens obtained before treatment. We found that the tumor had 256 non-synonymous mutations and 669 class I high-affinity binding neoantigen peptides. Using synthetic neoantigen peptides and ELISpot analysis, we found that peripheral blood mononuclear leukocytes cryopreserved before treatment contained pre-existing neoantigen-specific T cells, and the cells obtained after treatment exhibited greater reactivity to neoantigens than those obtained before treatment. Our results collectively suggest that the rapid and long-lasting effect of this combination therapy in our patient may have resulted from the presence of pre-existing neoantigen-specific T cells and stimulation and expansion of those cells following tumor lysate-pulsed DC vaccine and ICI therapy.PMID:34486463 | DOI:10.1080/08820139.2021.1973491

Source: Immunological Investigations - September 6, 2021 Category: Allergy & Immunology Authors: Shu Ichimiya Akiko Fujimura Muneyuki Masuda Shogo Masuda Ryuji Yasumatsu Masayo Umebayashi Hiroto Tanaka Norihiro Koya Shinichiro Nakagawa Poh Yin Yew Sachiko Yoshimura Hideya Onishi Masafumi Nakamura Yusuke Nakamura Takashi Morisaki Source Type: research