Clinical trials have demonstrated that monitoring PD-L1 expression through a novel blood test could significantly improve treatment outcomes for patients with metastatic breast cancer by guiding the use of immune checkpoint inhibitors. The LifeTracDx® blood test, developed by Creatv Bio, showed promising results in identifying patients who would benefit from combination immunotherapy approaches.
Breakthrough in PD-L1 Monitoring Technology
The LifeTracDx® blood test represents a significant advancement in cancer monitoring by capturing both circulating tumor cells (CTCs) and Cancer Associated Macrophage-Like (CAML) cells from patient blood samples. CAMLs are macrophages that have engulfed tumor cells from the tumor site, making both cell types ideal sources for companion diagnostics and real-time tumor monitoring.
In pooled clinical trial analysis of 28 patients with metastatic triple-negative breast cancer (mTNBC), researchers found that 76% of patients showed upregulation of PD-L1 expression after treatment with leronlimab, a CCR5 antagonist. This upregulation was successfully detected using the LifeTracDx® blood test, providing crucial information for subsequent treatment decisions.
Promising Four-Year Survival Outcomes
The most compelling evidence comes from four-year follow-up data presented at the ESMO Breast Cancer meeting on May 15, 2025, by Dr. Richard Pestell. Among patients who experienced significant PD-L1 upregulation as detected by the blood test and subsequently received treatment with immune checkpoint inhibitors atezolizumab or pembrolizumab, 5 patients remained alive after four years.
This survival data suggests that monitoring PD-L1 expression changes could serve as a valuable biomarker for identifying patients most likely to benefit from checkpoint inhibitor therapy, potentially transforming treatment sequencing in metastatic breast cancer.
Validation Across Multiple Cancer Vaccine Studies
Additional validation comes from a separate study involving 36 metastatic breast cancer patients treated with the SV-BR-1-GM vaccine in combination with the checkpoint inhibitor retifanlimab. This research, conducted in collaboration with The Mayo Clinic and BriaCell Therapeutics Corporation, was presented at the San Antonio Breast Cancer Symposium in December 2024.
The study revealed that SV-BR-1-GM therapy upregulated PD-L1 expression in 15 patients, which correlated with better responses to combination treatment with the anti-PD-L1 checkpoint inhibitor. Furthermore, a decrease in CTCs/CAMLs numbers significantly correlated with better progression-free survival and showed trends toward improved overall survival.
Clinical Applications and Rapid Response Prediction
The LifeTracDx® technology offers multiple clinical applications beyond PD-L1 monitoring. The test can predict treatment response within 30 days, provide companion diagnostics for various tumor markers, assess cancer aggressiveness, detect minimal residual disease, enable early detection of cancer recurrence, and support cancer screening efforts.
This rapid response prediction capability could significantly impact clinical decision-making by allowing physicians to adjust treatment strategies much earlier than traditional monitoring methods would permit.
Implications for Precision Oncology
The ability to monitor PD-L1 expression changes in real-time through blood samples represents a significant step forward in precision oncology for breast cancer patients. Rather than relying solely on tissue-based PD-L1 testing at diagnosis, this approach enables dynamic monitoring of biomarker expression throughout treatment, potentially optimizing the timing and selection of immunotherapy interventions.
The technology addresses a critical need in metastatic breast cancer treatment, where identifying patients most likely to respond to expensive and potentially toxic immunotherapy combinations remains challenging. By providing actionable biomarker information through a minimally invasive blood test, this approach could improve both patient outcomes and healthcare resource utilization.
