The analysis included 555 patients from the phase III GEICAM/2013-02 PEARL trial and used Biovica's FDA 510(k)-cleared DiviTum TKa assay. Patients were randomized to receive either targeted therapy (ET + palbociclib) or chemotherapy (capecitabine).

The key new insight is that TKa did not behave the same way across treatments. Instead, early TKa changes reflected how each therapy affected tumor biology — increasing in patients who benefited from capecitabine, an oral chemotherapy, while confirming previous findings that effective CDK4/6-based treatment is associated with early TKa suppression.

The authors also highlight that TKa provides unique information that may complement ctDNA. While ctDNA provides important genomic information about tumor mutations and clonal evolution, TKa provides a functional, real-time readout of tumor proliferation and biological treatment activity. In simple terms, ctDNA can help show what genetic changes are present, while TKa can help show what the cancer is doing during treatment.

"This analysis is part of GEICAM's commitment to advancing translational research with a real impact on clinical practice. TKa is a robust blood-based marker that makes it possible to monitor tumor activity in real time. Our study shows that its early changes, just 15 days after treatment begins, very clearly predict which patients are responding. It is a tool that can help us better understand treatment response and move toward increasingly personalized care in metastatic breast cancer," says Dr. Ángel Guerrero Zotano, one of the researchers involved in this study and member of GEICAM’s Board of Directors.

" What makes these findings particularly compelling is that TKa doesn't just confirm response — it differentiates it. The marker behaves distinctly depending on how a therapy works biologically, which means clinicians get a real-time functional signal that genomic tools simply cannot provide. As oncology accelerates toward truly personalized treatment, we believe DiviTum TKa is becoming an essential part of that picture — and data of this quality, at this scale, strengthens our confidence in the path ahead," says Theis Kipling, CEO of Biovica.