420 PROSTVAC in combination with nivolumab enhanced immune cell infiltration in prostate cancer

BackgroundProstate cancer (PC) is the most common non-cutaneous diagnosed cancer among men in USA.1 Although clinical outcomes are favorable for patients with localized disease, 20–30% of patients will develop metastatic prostate cancer (mPC) and have poor prognosis. Immunotherapy, as a single agent...

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Published in:Journal for immunotherapy of cancer 2021-11, Vol.9 (Suppl 2), p.A450-A450
Main Authors: Bailey, Shania, Lassoued, Wiem, Papanicolau-Sengos, Antonios, Marte, Jennifer, Williams, Nikki, Hankin, Amy, Manu, Michell, Dahut, William, Pinto, Peter, Karzai, Fatima, Madan, Ravi, Sater, Houssein Abdul, Gulley, James
Format: Article
Language:English
Subjects:
Immunotherapy
Lymphocytes
Monoclonal antibodies
Prostate cancer
Regular and Young Investigator Award Abstracts
Targeted cancer therapy
Vaccines
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Summary:BackgroundProstate cancer (PC) is the most common non-cutaneous diagnosed cancer among men in USA.1 Although clinical outcomes are favorable for patients with localized disease, 20–30% of patients will develop metastatic prostate cancer (mPC) and have poor prognosis. Immunotherapy, as a single agent, provides benefit to a small subset of PC patients, which is thought to be partially due to its known cold tumor immune microenvironment (TIME). Combination studies are needed to enhance benefit.2 Prostvac is a therapeutic cancer vaccine engineered to activate an immune response against prostate-specific Antigen (PSA).3 Prostvac alone could induce systemic immune response by increasing immune-cell infiltrates in and around the tumor.4 In this study, we are exploring the effect of Prostvac in combination with nivolumab in TIME in prostate cancer.MethodsWe treated locally advanced prostate cancer patients (n=6) undergoing radical prostatectomy (RP) with neoadjuvant Prostvac in combination with nivolumab, an immune checkpoint PD-1 inhibitor. Dynamic changes in TIME before and after treatment were studied using multiplex immunofluorescence (Opal Method). Formalin fixed paraffin-embedded sections from matched pre-treated prostate biopsies and post-treated RP samples were stained with a validated T cell panel (DAPI, CD4, CD8, FOXP3, Ki67, Pan CK and PD-L1). To analyze the data, TIME was segmented into 3 compartments: intratumoral, invasive margin and benign.ResultsCombination immunotherapy significantly increased CD4+ T cell density in the invasive margin (mean 211.5 cells/mm2 vs 592.2 cells/mm2, p
ISSN:2051-1426
DOI:10.1136/jitc-2021-SITC2021.420