Foffano Lorenzo, Franzoni Alessandra, Molteni Elisabetta, Giudici Fabiola, Dri Arianna, Basile Debora, Cucciniello Linda, Buriolla Silvia, Noto Claudia, Russo Stefania, Nascimbeni Elena, Bolzonello Silvia, Pastò Brenno, Rossa Serena Della, Allegri Lorenzo, Bonotto Marta, Minisini Alessandro Marco, Belletti Barbara, Damante Giuseppe, Gerratana Lorenzo, Puglisi Fabio
Department of Medical Oncology, CRO di Aviano, National Cancer Institute, IRCCS, 33081 Aviano, Italy; Department of Medicine, University of Udine, 33100 Udine, Italy.
Institute of Human Genetics, Santa Maria della Misericordia University Hospital, Azienda Sanitaria Universitaria Friuli Centrale (ASUFC), 33100 Udine, Italy.
Transl Oncol. 2025 Jun 26;59:102456. doi: 10.1016/j.tranon.2025.102456.
In the context of hormone receptor positive, HER2 negative Metastatic breast cancer (MBC), CDK 4/6 inhibitors (CDK4/6i) combined with endocrine therapy represent the standard first-line treatment, improving Progression-Free Survival (PFS) and Overall Survival (OS). Despite these benefits, resistance to treatment develops, necessitating early risk classification to guide clinical management. This study explores the potential of cell-free DNA (cfDNA) fragmentomics, specifically ACTB fragments, in predicting tumor dynamics and treatment outcomes in luminal MBC, based on the principle that shorter DNA fragments are generally indicative of circulating tumor DNA (ctDNA) from tumor cells, while longer fragments are associated with leukocyte lysis.
In the MAGNETIC.1 study, 141 women with luminal-like MBC were enrolled between January 2018 and January 2023. Blood samples were collected at baseline (BL), and after 3 (T3) and 6 (T6) months of treatment. cfDNA was extracted and analyzed using droplet digital PCR (ddPCR) to quantify ACTB fragments (136 bp, 420 bp, and 2,000 bp). Continuous variables were compared using the Mann-Whitney test and Kruskall Wallis test depending on data distribution and number of groups. Categorical variables were compared using the Chi-square test or Fischer's exact test whenever appropriate. Differences in survival were tested by log-rank test and uni- and multivariable Cox regression.
By categorizing the values of actinic fragments into interquartiles (Q1, Q2, and Q3), ACTB Q3 at baseline was significantly associated with negative PR expression (RRR 0.27, P = 0.012) and a higher frequency of liver metastasis (RRR = 3.75, P = 0.009). In terms of clinical outcomes, regarding PFS a significant role was observed for baseline ACTB Q3 (HR 1.92, P = 0.041) and ACTB Q3 (HR 0.47, P = 0.043), the latter maintaining significance in multivariable analysis (HR 0.33, 95 %, P = 0.012). For OS, ACTB Q3 demonstrated a significant impact in both univariable (HR 3.94, P = 0.003) and multivariable analyses (HR 3.25, P = 0.023).
This study demonstrates the feasibility of employing a fragmentomics mutation agnostic approach in luminal MBC. Baseline and longitudinal changes in ACTB fragments were significantly associated with clinical outcomes, suggesting their potential as non-invasive biomarkers for early risk classification and monitoring tumor dynamics.
在激素受体阳性、人表皮生长因子受体2阴性的转移性乳腺癌（MBC）中，细胞周期蛋白依赖性激酶4/6抑制剂（CDK4/6i）联合内分泌治疗是标准的一线治疗方案，可改善无进展生存期（PFS）和总生存期（OS）。尽管有这些益处，但治疗仍会产生耐药性，因此需要进行早期风险分类以指导临床管理。本研究基于较短的DNA片段通常指示肿瘤细胞来源的循环肿瘤DNA（ctDNA），而较长片段与白细胞裂解相关的原理，探讨游离DNA（cfDNA）片段组学，特别是肌动蛋白β（ACTB）片段，在预测管腔型MBC肿瘤动态和治疗结果方面的潜力。
在MAGNETIC.1研究中，2018年1月至2023年1月期间招募了141例管腔样MBC女性患者。在基线（BL）以及治疗3个月（T3）和六个月（T6）后采集血样。提取cfDNA并使用液滴数字PCR（ddPCR）进行分析，以定量ACTB片段（136 bp、420 bp和2000 bp）。根据数据分布和组数，使用Mann-Whitney检验和Kruskall Wallis检验比较连续变量。分类变量在适当情况下使用卡方检验或Fisher精确检验进行比较。通过对数秩检验以及单变量和多变量Cox回归检验生存差异。
通过将肌动蛋白片段的值分类为四分位数间距（Q1、Q2和Q3），基线时的ACTB Q3与孕激素受体（PR）阴性表达显著相关（相对风险降低率0.27，P = 0.012）以及肝转移频率较高（相对风险降低率= 3.75，P = 0.009）。在临床结果方面，关于PFS，观察到基线ACTB Q3（风险比1.92，P = 0.041）和T6时的ACTB Q3（风险比0.47，P = 0.043）具有显著作用，后者在多变量分析中仍具有显著性（风险比0.33，95%，P = 0.012）。对于OS，ACTB Q3在单变量（风险比3.94，P = 0.003）和多变量分析（风险比3.25，P = 0.023）中均显示出显著影响。
本研究证明了在管腔型MBC中采用片段组学突变不可知方法的可行性。ACTB片段的基线和纵向变化与临床结果显著相关，表明它们作为早期风险分类和监测肿瘤动态的非侵入性生物标志物的潜力。
