ORIGINAL RESEARCH article
Front. Immunol.
Sec. Cancer Immunity and Immunotherapy
This article is part of the Research TopicTranslational Research on Cancer Immunity and Immunotherapy: Preclinical and Clinical Investigations from Latin AmericaView all articles
UNRAVELLING THE COMPLEXITY OF THE INTERACTIONS AMONG VACCIMEL, BCG AND BLOOD MONOCYTES
Provisionally accepted
Erika Schwab1,2Brenda Carles2
ALICIA INES BRAVO2,3María Victoria Echenique2Agustina De Franc4
Mariano Guillermo Bonanno3
María Marcela Barrio2
José Mordoh2*- 1Universidad de Buenos Aires Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina
- 2Centro de Investigaciones Oncológicas, Fundación Cáncer, Buenos Aires, Capital federal, Argentina
- 3Hospital Interzonal General de Agudos Eva Peron, Buenos Aires, Argentina
- 4LANAIS-MIE, Instituto de Biología Celular y Neurociencia Prof. E. De Robertis, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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VACCIMEL is an immunotherapeutic adjuvant treatment for high-risk cutaneous melanoma. It consists of 13 intradermal injections of four irradiated melanoma cell lines co-adjuvated with BCG and GM-CSF. VACCIMEL prolongs distant metastases-free survival and it induces T lymphocytes reactive against melanoma differentiation antigens, cancer testis antigens, and neoantigens. In this paper, we have studied in vitro the interaction among VACCIMEL, BCG, and blood-derived monocytes, a fundamental component of innate immunity. We have demonstrated that monocytes may phagocytose, separately and jointly, BCG and VACCIMEL. We have demonstrated for the first time by transmission electron microscopy, detailed features of irradiated melanoma cells phagocytosis and its timeline. We have equally demonstrated that monocytes may process and cross-present tumor antigens to CD8+ T cells and that BCG interferes with that process in a multiplicity of infection (MOI) - dependent manner. BCG induces high production of IL-10 by monocytes which is several-fold reduced by phagocytosis of tumor antigens. Although cross-presentation is still inhibited in the presence of a high BCG MOI (0.4), it rebounds by reducing tenfold the BCG MOI from 0.4 to 0.04. This suggests that an adequate balance between tumor antigens and BCG phagocytosis is needed to retain the stimulatory properties of activated monocytes and trigger immunogenicity of tumor antigens.
Keywords: BCG, cutaneous melanoma, Immunotherapy, innate immune cells, Monocytes, Phagocytosis
Received: 23 Oct 2025; Accepted: 11 Feb 2026.
Copyright: © 2026 Schwab, Carles, BRAVO, Echenique, De Franc, Bonanno, Barrio and Mordoh. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: José Mordoh
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