Increased blood draws for ultrasensitive ctDNA and CTCs detection in early breast cancer patients

Early breast cancer patients often experience relapse due to residual disease after treatment. Liquid biopsy is a methodology capable of detecting tumor components in blood, but low concentrations at early stages pose challenges. To detect them, next-generation sequencing has promise but entails complex processes. Exploring larger blood volumes could overcome detection limitations. Herein, a total of 282 high-volume plasma and blood-cell samples were collected for dual ctDNA/CTCs detection using a single droplet-digital PCR assay per patient. ctDNA and/or CTCs were detected in 100% of pre-treatment samples. On the other hand, post-treatment positive samples exhibited a minimum variant allele frequency of 0.003% for ctDNA and minimum cell number of 0.069 CTCs/mL of blood, surpassing previous investigations. Accurate prediction of residual disease before surgery was achieved in patients without a complete pathological response. A model utilizing ctDNA dynamics achieved an area under the ROC curve of 0.92 for predicting response. We detected disease recurrence in blood in the three patients who experienced a relapse, anticipating clinical relapse by 34.61, 9.10, and 7.59 months. This methodology provides an easily implemented alternative for ultrasensitive residual disease detection in early breast cancer patients.

Abstract 6610: Increasing blood volumes to detect minimal residual disease in neoadjuvant-treated early breast cancer patients

Breast cancer (BC) is the most frequent neoplasia affecting women worldwide normally detected at early stages. In this regard, early diagnosis drastically decreases mortality, however, around 20% of these patients will later relapse. This is mainly caused by undetectable molecular residual disease (MRD) not eliminated by standard primary treatments. Therefore, it is crucial to detect the after-treatment MRD to stratify the patients by their risk of relapse. Liquid biopsies have emerged as non-invasive method to obtain information about tumors and improve clinical cancer management. Regarding this, much has been hypothesized about utilizing high blood volumes to overcome the necessity of complex and resource-intensive next generation sequencing (NGS) methodologies to detect highly diluted blood tumor components in localized cancers. Herein, we employed a combined analysis of circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) together with high blood volumes and single-assay droplet digital PCR (ddPCR) to detect MRD with ultra-high sensitivity. We prospectively assayed 124 samples extracted at baseline, post-neoadjuvant therapy (NAT), post-surgery and a follow-up on a six-monthly basis. A median of 76.40 mL of blood to detect CTCs and 40 mL of plasma to detect ctDNA per patient from 19 BC women were used in this study. ddPCR assays were performed with a median of 14 partitions per determination to detect ctDNA and 12 partitions for CTCs. Overall, ctDNA, CTCs and ctDNA and/or CTCs were detected in 84.21%, 66.66% and 89.47% respectively in the pre-treatment blood samples. MRD (ctDNA and/or CTCs) was detected in 73.68% of the after NAT blood samples. On the other hand, it was detected in 46.66% and 70.00% of the post-surgery and follow-up samples respectively. Post-NAT MRD was detected in 57.14% (4/7) and 83.33% (10/12) of patients with and without pathological complete response pCR respectively. To note, the discordant patients achieving pCR in tissue with detectable MRD in blood were high-risk BC. Importantly, in one of the two patients without pCR and no MRD detected, not enough sample were available to complete the analysis. The other discordant patient presented a localized disease with residual cancer burden value of 1 and no lymph nodes affected. In 1 out of 19 (5.26%) patient clinically relapsed with a positive MRD detection 6 months earlier. Applying this methodology, we observed a sensitivity of 0.004% in ctDNA detection and 0.224 CTCs per mL of blood. Overall, this novel methodology greatly improves sensitivity for ctDNA and CTCs detection in treatment-naïve early BC. In addition, MRD was successfully detected in post-treatment samples antedating clinical relapse by 6 months in one patient. This prospective study is potentially demonstrating that using high blood volumes and a single-assay ddPCR is a cost-effective strategy to monitor localized BC and predict relapses.

Citation Format: Alfonso Alba-Bernal, Ana Godoy-Ortiz, María Emilia Domínguez-Recio, Begoña Jimenez-Rodriguez, María Elena Quirós-Ortega, Esperanza López-López, Guillermo Carbajosa-Antona, Jesús Peralta-Linero, Luis Vicioso, Estefanía Bellagarza-García, Guadalupe Dolores Garrido-Ruiz, Cynthia Robles-Podadera, Alicia Garrido-Aranda, María Dunia Roldán-Díaz, Jesús Velasco-Suelto, Rocío Lavado-Valenzuela, Martina Álvarez, Nuria Ribelles, Javier Pascual, Emilio Alba, Iñaki Comino-Méndez. Increasing blood volumes to detect minimal residual disease in neoadjuvant-treated early breast cancer patients. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6610.

Development of in vitro and in vivo tools to evaluate the antiangiogenic potential of melatonin to neutralize the angiogenic effects of VEGF and breast cancer cells: CAM assay and 3D endothelial cell spheroids

Melatonin is a molecule with different antitumor actions in breast cancer and has been described as an inhibitor of vascular endothelial growth factor (VEGF). Despite the recognition of the key role exerted by VEGF in tumor angiogenesis, limitations arise when developing models to test new antiangiogenic molecules. Thus, the aim of this study was to develop rapid, economic, high capacity and easy handling angiogenesis assays to test the antiangiogenic effects of melatonin and demonstrate its most effective dose to neutralize and interfere with the angiogenic sprouting effect induced by VEGF and MCF-7. To perform this, 3D endothelial cell (HUVEC) spheroids and a chicken embryo chorioallantoic membrane (CAM) assay were used. The results showed that VEGF and MCF-7 were able to stimulate the sprouting of the new vessels in 3D endothelial spheroids and the CAM assay, and that melatonin had an inhibitory effect on angiogenesis. Specifically, as the 1 mM pharmacological dose was the only effective dose able to inhibit the formation of ramifications around the alginate in the CAM assay model, this inhibition was shown to occur in a dose-dependent manner. Taken together, these techniques represent novel tools for the development of antiangiogenic molecules such as melatonin, with possible implications for the therapy of breast cancer.

A New Paradigm in the Relationship between Melatonin and Breast Cancer: Gut Microbiota Identified as a Potential Regulatory Agent

In this review we summarize a possible connection between gut microbiota, melatonin production, and breast cancer. An imbalance in gut bacterial population composition (dysbiosis), or changes in the production of melatonin (circadian disruption) alters estrogen levels. On the one hand, this may be due to the bacterial composition of estrobolome, since bacteria with β-glucuronidase activity favour estrogens in a deconjugated state, which may ultimately lead to pathologies, including breast cancer. On the other hand, it has been shown that these changes in intestinal microbiota stimulate the kynurenine pathway, moving tryptophan away from the melatonergic pathway, thereby reducing circulating melatonin levels. Due to the fact that melatonin has antiestrogenic properties, it affects active and inactive estrogen levels. These changes increase the risk of developing breast cancer. Additionally, melatonin stimulates the differentiation of preadipocytes into adipocytes, which have low estrogen levels due to the fact that adipocytes do not express aromatase. Consequently, melatonin also reduces the risk of breast cancer. However, more studies are needed to determine the relationship between microbiota, melatonin, and breast cancer, in addition to clinical trials to confirm the sensitizing effects of melatonin to chemotherapy and radiotherapy, and its ability to ameliorate or prevent the side effects of these therapies.