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experimental model, from a Gr1 CD11b cell dominated response in mice with progressive tumors toward
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a CD4 /CD8 -, B cell and CD11c cell-dominated response in mice with dormant tumors [226] . Thus, Serum
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IFN-β levels and immunophenotyping should be explored for their potential use as biomarkers of breast
cancer dormancy.
CONCLUSION
Advances in the understanding of the mechanisms of breast cancer dormancy have raised the hope to
therapeutically exploit dormancy to prevent relapses and overt metastatic disease. To date many potential
therapeutic targets and strategies have been considered and proposed for clinical testing [100,185] . However,
many of these approaches would be difficult to apply to patients due to lack of suitable drugs, potential long-
term toxicity and over all complexity in the in their clinical translation. Recent reports implicating a T cell
based immune response in the therapeutic effects of chemotherapy including dormancy, have opened novel
perspectives for a feasible clinical translation. Administration of chemotherapy before tumor removal (i.e.,
neoadjuvant chemotherapy) may be explored for improved effects on immunological dormancy compared to
conventional, post-surgery, adjuvant chemotherapy. Drugs with potential beneficial effects on promoting or
prolonging dormancy, such as NSAIDs to suppress inflammation, type I interferons, check-point inhibitors
or anti-angiogenic drugs to stimulate the immune response, are available for clinical use and could be
tested in combination with chemotherapy. Thus, the observation that chemotherapy can induce a state of
immunological dormancy adds a new therapeutic effect to the older class of anti-cancer drugs and opens
unanticipated therapeutic opportunities for clinical translation in breast cancer (and possibly other cancers).

DECLARATIONS
Acknowledgments
We apologize for not being able to cite all published work relevant to this topic due to space limitation and
selective focus of the article.

Authors’ contributions
Conceiving the paper: Peyvandi S, Lan Q, Lorusso G, Rüegg C
Writing the paper: Peyvandi S, Lan Q, Lorusso G, Rüegg C
Performed the work of immunological dormancy in the laboratory: Peyvandi S, Lan Q, Lorusso G, Rüegg C

Availability of data and materials
Not applicable.

Financial support and sponsorship
This work was supported by the Swiss National Sciences foundation (31003A_159824/1, 31003A_179248/1);
the Swiss Cancer League (KSF3513-08-2014, KSF-4400-02-2018); NCCR Molecular Oncology, NCCR Bio-
Inspired materials, the Medic Foundation, the Sassella Stiftung, the 3R foundation, and the European Union
under the auspices of the FP7 collaborative project TuMIC (HEALTH-F2-2008-201662).

Conflicts of interest
All authors declare that there are no conflicts of interest.

Ethical approval and consent to participate
Not applicable.

Consent for publication
Not applicable.