Tumor-lock: forbid the generation of circulating tumor cells

Project Information

TUMOR-LOCK

Grant agreement ID: 101001652

DOI

10.3030/101001652

Project closed

EC signature date 13 April 2021

Start date 1 June 2021

End date 31 May 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 999 995,00

EU contribution

€ 1 999 995,00

Coordinated by

EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH
Switzerland

Periodic Reporting for period 4 - TUMOR-LOCK (Tumor-lock: forbid the generation of circulating tumor cells)

Reporting period: 2025-12-01 to 2026-05-31

Summary of the context and overall objectives of the project

No therapies are currently designed with the goal to prevent the spread of cancer. Rather, the general aim is to kill cancer cells, which may delay but not prevent metastasis formation, mostly due to the emergence of drug-resistant clones that are positively selected during a tumor-killing approach. Mechanisms that promote the spread of breast cancer cells have been investigated, yet, surprisingly, little is known about the molecular events that dictate their entry into the bloodstream (a.k.a. intravasation) and as a consequence, no anti-metastasis therapeutic approaches have emerged. Our project aims to go far beyond standard approaches, and identify a non-tumor-killing approach that selectively impairs
the entry of tumor cells into the circulation, thereby locking tumor cells in situ while avoiding selection for drug-resistant clones. We envision our “tumor-lock” strategy to be compatible with simultaneous administration of standard-of-care therapies during tumor progression, and to benefit patients at virtually all stages, i.e. suppressing both primary-to-metastasis and metastasis-to-metastasis cascading dissemination.

We hypothesize that our approach will lead to the identification of new targets, whose inhibition will blunt the ability of cancer cells to intravasate, resulting in metastasis prevention. Our Aims are specifically designed to test this hypothesis.

Particularly: in Aim 1 we will identify fundamental mechanisms governing CTC generation. This will include investigations of the tumor microenvironment, transcriptomic, genomic and epigenomic patterns, the circadian rhythm and the immune system. In Aim 2 we will identify actionable targets and treatment opportunities. This will include CRISPR-based genetic engineering and target identification, as well as phenotypic drug screens.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

We have found that the circadian rhythm strongly affects the dynamics of CTC generation. (Diamantopoulou et al., Nature, 2022)
Summary:
The metastatic spread of cancer is achieved by the hematogenous dissemination of circulating tumor cells (CTCs). Generally, however, the temporal dynamics that govern the generation of metastasis-competent CTCs are largely uncharacterized, with the assumption that CTCs are constantly shed from growing tumors or as a consequence of mechanical insults. In this study, we have observed a striking and unexpected pattern of CTC generation dynamics in both patients with breast cancer and mouse models, highlighting that the vast majority of spontaneous CTC intravasation events occur during the rest phase. Furthermore, we demonstrated that rest-phase CTCs are highly prone to metastasis, whereas CTCs generated during the active phase lack metastatic potential. Mechanistically, single-cell-resolution RNA sequencing of CTCs revealed a dramatic upregulation of mitotic genes exclusively during the rest phase in both patients and mouse models, thereby enabling metastasis proficiency. Mechanistically, we found that key circadian rhythm hormones such as melatonin, testosterone, and glucocorticoids govern CTC generation dynamics and, as a consequence, that insulin directly promotes tumor cell proliferation in vivo, albeit in a time-dependent manner. Thus, the spontaneous generation of CTCs with a high proclivity to metastasize does not occur continuously but is concentrated during the rest phase of the host, providing a new rationale for time-controlled interrogation and treatment of metastasis-prone cancers.

Additional investigations related to the intravasation process have been completed. These include the characterization of the intracellular heterogeneity of CTC clusters (Gremmelspacher et al., Nature Genetics, 2025), clinical proof-of-concept for CTC cluster disruption (Kurzeder et al., Nature Medicine, 2025), CRISPR screens in immunocompetent models to reveal additional CTC cluster vulnerabilities (Saini et al., Cell, 2025), and the role of Ki67 in breast cancer intravasation (Zhang et al., Cell Reports, 2026).

Exploitation and dissemination of the results have focused on presentations at international conferences or symposia, and ongoing discussions with investors and third parties interested in developing new targeting concepts.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our discovery that CTC dynamics are regulated by the circadian rhythm (Diamantopoulou et al., Nature, 2022) has opened entirely new avenues for developing therapeutic strategies in breast cancer. These include time-of-day-driven diagnostic and therapeutic approaches that will need to be tested in future clinical studies. As the project comes to a conclusion, we can also report additional findings on the intravasation process, including mechanisms underlying vascular invasion and the role of Ki67 in promoting breast cancer spread.