Immunization With the CSF-470 Vaccine Plus BCG and rhGM-CSF Induced in a Cutaneous Melanoma Patient a TCRβ Repertoire Found at Vaccination Site and Tumor Infiltrating Lymphocytes That Persisted in Blood
Authors: Mariana Aris, Alicia Inés Bravo, Heli Magalí Garcia Alvarez, Ibel Carri, Enrique Podaza, Paula Alejandra Blanco, Cecilia Rotondaro, Sofia Bentivegna, Morten Nielsen, María Marcela Barrio, José Mordoh
Journal: Front Immunol (2019)
Keywords: csf-470 vaccine, tcrβ repertoire, cutaneous melanoma, cutaneous metastasis, tumor infiltrating lymphocytes, vaccination site
MeSH terms: Cancer Vaccines / therapeutic use, Lymphocytes, Tumor-Infiltrating / immunology, Melanoma / drug therapy, Melanoma / immunology, Skin Neoplasms / drug therapy, Skin Neoplasms / immunology, Case Reports, Research Support, Non-U.S. Gov't, BCG Vaccine / therapeutic use, Granulocyte-Macrophage Colony-Stimulating Factor / therapeutic use, Humans, Lymphocytes, Tumor-Infiltrating / drug effects, Male, Middle Aged, Receptors, Antigen, T-Cell, alpha-beta / immunology, BCG Vaccine, Cancer Vaccines, Receptors, Antigen, T-Cell, alpha-beta, Granulocyte-Macrophage Colony-Stimulating Factor, Melanoma, Cutaneous Malignant

The CSF-470 cellular vaccine plus BCG and rhGM-CSF increased distant metastases-free survival in cutaneous melanoma patients stages IIB-IIC-III relative to medium dose IFN-α2b (CASVAC-0401 study). Patient-045 developed a mature vaccination site (VAC-SITE) and a regional cutaneous metastasis (C-MTS), which were excised during the protocol, remaining disease-free 36 months from vaccination start. CDR3-TCRβ repertoire sequencing in PBMC and tissue samples, along with skin-DTH score and IFN-γ ELISPOT assay, were performed to analyze the T-cell immune response dynamics throughout the immunization protocol. Histopathological analysis of the VAC-SITE revealed a highly-inflamed granulomatous structure encircled by CD11c+ nested-clusters, brisk CD8+ and scarce FOXP3+, lymphocytes with numerous Langhans multinucleated-giant-cells and macrophages. A large tumor-regression area fulfilled the C-MTS with brisk lymphocyte infiltration, mainly composed of CD8+PD1+ T-cells, CD20+ B-cells, and scarce FOXP3+ cells. Increasing DTH score and IFN-γ ELISPOT assay signal against the CSF-470 vaccine-lysate was evidenced throughout immunization. TCRβ repertoire analysis revealed for the first time the presence of common clonotypes between a VAC-SITE and a C-MTS; most of them persisted in blood by the end of the immunization protocol. In vitro boost with vaccine-lysate revealed the expansion of persistent clones that infiltrated the VAC-SITE and/or the C-MTS; other persistent clones expanded in the patient's blood as well. We propose that expansion of such persistent clonotypes might derive from two different although complementary mechanisms: the proliferation of specific clones as well as the expansion of redundant clones, which increased the number of nucleotide rearrangements per clonotype, suggesting a functional antigenic selection. In this patient, immunization with the CSF-470 vaccine plus BCG and rhGM-CSF induced a T-cell repertoire at the VAC-SITE that was able to infiltrate an emerging C-MTS, which resulted in the expansion of a T-cell repertoire that persisted in blood by the end of the 2-year treatment.