精准选择三阴性乳腺癌新白金方案
三阴性乳腺癌的雌激素受体、孕激素受体、人类表皮生长因子受体HER2均为阴性，对内分泌治疗和HER2靶向治疗无效，术后全身治疗主要依靠化疗。三阴性乳腺癌化疗金标准方案主要包括环磷酰胺＋氟尿嘧啶＋蒽环类→紫杉类。近年来，对于晚期三阴性乳腺癌患者和早期三阴性乳腺癌术前患者，金标准方案加入铂类的优效性已被随机对照研究证实。不过，对于早期三阴性乳腺癌术后患者，既往随机对照研究未能证实金标准方案加入铂类的优效性。2020年，《美国医学会杂志》肿瘤学分册发表复旦大学附属肿瘤医院余科达、邵志敏等学者的PATTERN研究报告，首次证实新白金方案（紫杉醇＋卡铂）对于三阴性乳腺癌术后患者优于金标准方案（环磷酰胺＋氟尿嘧啶＋表柔比星→多西他赛）。
PATTERN (NCT01216111): Adjuvant Platinum and Taxane in Triple-negative Breast Cancer (A Prospective, Randomized, Open-label, Multicentric, phase III Clinical Trial Compared With PC and CEF100 Followed by Docetaxel as Adjuvant Chemotherapy Regimen for Chinese Primary Triple Negative Breast Cancer Patients)
由于三阴性乳腺癌与DNA同源重组修复相关基因突变引起的全基因组不稳定性密切相关，而铂类主要作用于DNA，故PATTERN研究早在2010年设计之初就决定对DNA同源重组修复相关基因等进行多组学分析，确定哪些生物标志物有助于精准选择三阴性乳腺癌术后化疗方案。
2021年9月26日，国际转化医学会《临床与转化医学》（Clin Transl Med. IF: 11.492）在线发表复旦大学附属肿瘤医院朱思远、马丁、叶富贵、邵志敏、余科达等学者的PATTERN研究基因组特征和生物标志物分析，对三阴性乳腺癌术后化疗的同源重组缺陷和糖酵解相关通路进行了详细解读。
该研究对其中132例患者进行全外显子组测序、转录组测序、拷贝数检测等多组学分析（图S1），并对患者的无复发生存进行长期随访。PATTERN研究多组学队列与整个队列的两组患者特征分布参见表S1。随后，利用国际乳腺癌分子分类联盟 (METABRIC) 数据库165例三阴性乳腺癌术后蒽环类＋紫杉类化疗患者的转录组数据进行外部验证，PATTERN研究多组学队列与METABRIC队列的特征比较参见表S2。
结果发现，该多组学队列的金标准方案化疗组69例患者与新白金方案化疗组63例患者相比，临床病理特征和分子特征相似（表1），与复旦大学附属肿瘤医院整个三阴性乳腺癌队列相比，分子亚型组成相似（图1A）。TP53、PIK3CA、KMT2C、PTEN、NF1是突变率最高的基因（76.4%、18.0%、9.0%、6.7%、5.6%，图1B）。同源重组缺陷相关特征（特征3和8）和CLOCK样特征（特征1和5）是主要的突变特征（图1C）。根据拷贝数对该队列115例患者进行同源重组缺陷评分（据报道是铂类方案疗效的潜在预测指标）中位值为26.0（图1D）。
图1
重组修复缺陷评分与两种不同化疗方案的无复发生存显著相关（相互作用P=0.01），而重组修复缺陷相关突变特征与不同化疗方案未见统计学显著相互影响（P=0.19）。
新白金方案与金标准方案相比：
重组修复缺陷评分高于中位值的患者复发或死亡风险低70%（图2A，风险比：0.30，95%置信区间：0.09～0.95，P=0.03）
重组修复缺陷评分低于中位值的患复发或死亡风险相似（图2B，风险比：1.53，95%置信区间：0.59～3.96，P=0.38）
同样，重组修复缺陷评分高于与低于中位值的患者相比：
新白金方案的复发或死亡风险低64%（风险比：0.36，95%置信区间：0.11～1.19，P=0.08）
金标准方案的复发或死亡风险相似（风险比：1.81，95%置信区间：0.72～4.53，P=0.20）。
虽然同源重组缺陷是可逆的，但是即使缺陷不再活跃，突变特征并未消失。
新白金方案与金标准方案相比：
同源重组缺陷相关突变特征值高于中位值的患者复发或死亡风险低74%（图2C，风险比：0.26，95%置信区间：0.06～1.20，P=0.06）
同源重组缺陷相关突变特征值低于中位值的患者复发或死亡风险相似（图2D，风险比：0.97，95%置信区间：0.31～3.04，P=0.96）。
不过，同源重组缺陷相关突变特征值高于与低于中位值的患者相比：
新白金方案的复发或死亡风险相似（风险比：0.39，95%置信区间：0.08～1.95，P=0.24）
金标准方案的复发或死亡风险相似（风险比：1.61，95%置信区间：0.56～4.63，P=0.37）。
图2
根据同源重组缺陷评分和同源重组缺陷相关突变特征，对新白金方案与金标准方案进行多因素分析，结果与单因素分析一致（表S3）。
该研究利用转录组测序数据，还发现金标准方案化疗患者的缺氧和糖酵解相关通路与不良预后相关（图3A）。对于METABRIC队列三阴性乳腺癌化疗患者，该发现得到验证（图3B）。
此外，REACTOME糖酵解评分较高与较低的患者相比：
金标准方案的复发或死亡风险显著较高（图3C左，风险比：3.43，95%置信区间：1.37～8.60，P=0.01）
新白金方案的复发或死亡风险相似（图3C中，风险比：0.47，95%置信区间：0.10～2.23，P=0.33）。
对于METABRIC队列三阴性乳腺癌化疗患者，也验证了REACTOME糖酵解评分较高的患者复发或死亡风险显著较高（图3C右，风险比：1.72，95%置信区间：1.08～2.73，P=0.02）。
图3
因此，该研究结果表明，对于同源重组缺陷评分较高的患者，新白金方案与金标准方案相比，复发或死亡风险显著较低，反映卡铂辅助化疗方案可能为同源重组缺陷活跃的三阴性乳腺癌人群带来更多获益。利用同源重组缺陷评分，可以扩大新白金方案的候选人群。同样，对于同源重组缺陷相关突变特征值较高的患者，新白金方案与金标准方案相比，复发或死亡风险也显著较低。由于该研究样本量较小，故有必要进一步开展大样本研究进行验证。
此外，对于金标准方案队列，可见糖酵解上调和缺氧相关通路与不良预后相关，并且METABRIC队列也验证了类似的结果。代谢重编程是肿瘤细胞的主要标志，化疗耐药的三阴性乳腺癌细胞通常表现出糖酵解表现型增强。肿瘤细胞可能通过改变其代谢通路基因表达，对蒽环类＋紫杉类化疗方案产生耐药，糖酵解抑制剂可能成为有希望的治疗新策略。
总之，同源重组缺陷评分可以作为三阴性乳腺癌术后精准选择化疗方案、预测新白金方案疗效的生物标志物，而糖酵解和缺氧相关通路上调可能参与蒽环类＋紫杉类化疗方案耐药，代谢改变是否参与耐药有待进一步研究，相关治疗策略值得探索。
相关链接
Clin Transl Med. 2021 Sep 26;11(9):e513.
Homologous recombination deficiency and glycolysis-related pathway in adjuvant chemotherapy for triple-negative breast cancer: A genomic landscape and biomarker assessment of the PATTERN trial.
Zhu SY, Ma D, Ye FG, Shao ZM, Yu KD.
Fudan University Shanghai Cancer Center, Shanghai, China; Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Key Laboratory of Breast Cancer, Shanghai, China.
Triple-negative breast cancer (TNBC) is associated with genome-wide instability caused by mutations in homologous recombination repair mechanism, and the application of DNA-damaging compounds has been explored for TNBC. Recently, we performed the PATTERN trial (NCT01216111) to compare six cycles of paclitaxel plus carboplatin (PCb) with a standard-dose regimen of three cycles of cyclophosphamide/epirubicin/fluorouracil followed by three cycles of docetaxel (CEF-T) in the adjuvant setting of early-stage TNBC, and the result indicated a superior efficacy of the carboplatin-containing regimen and good tolerance to both treatments. In this study, we conducted multi-omic profiling on 132 patients in the PATTERN cohort to investigate potential biomarkers for a more precise choice of adjuvant chemotherapy regimen for TNBC. We found that homologous recombination deficiency (HRD) score might serve as a biomarker of adjuvant carboplatin-containing regimen for TNBC, and upregulation of glycolysis and hypoxia-related pathways might participate in underlying mechanisms of anthracycline/taxane-based regimen resistance.
The abovementioned 132 patients in the PATTERN cohort have been enrolled into the Fudan University Shanghai Cancer Center Triple-Negative Breast Cancer (FUSCC-TNBC) program to receive whole-exome sequencing, RNA sequencing, and copy number detection. We investigated the association of multi-omic data with relapse-free survival (RFS) to explore potential biomarkers. Figure S1 shows the distribution of cases enrolled. Table S1 demonstrated characteristics of the PATTERN cohort and the patients involved. Additional transcriptomic data of 165 TNBC patients who received anthracycline/taxane-based chemotherapy in the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) database were analyzed for external validation. Table S2 illustrates the characteristics of these patients.
Clinicopathologic and molecular characteristics were similar between the two arms (Figure 1 and Table 1). FUSCC subtype composition of this cohort was similar to that of the whole FUSCC-TNBC cohort (Figure 1A). TP53 (76.4%), PIK3CA (18.0%), KMT2C (9.0%), PTEN (6.7%), and NF1 (5.6%) were the most frequently mutated genes (Figure 1B). HRD-related signatures (signature 3 and 8) and clock-like signatures (signature 1 and 5) were the dominant mutational signatures (Figure 1C). Furthermore, 115 cases in this cohort with copy number-based HRD score, which has been reported to be a potential predictor for a platinum-containing regimen, had a median value of 26.0 (Figure 1D).
Subsequently, we investigated the predictive effect of HRD score and HRD-related mutational signature. We found the interaction of HRD score and the two different chemotherapy regimens for RFS was significant (interaction p = 0.01), while there was no statistically significant interaction between HRD-related mutational signature and different treatments (interaction p = 0.19). Then, patients were sorted by their HRD score value regardless of the regimen. In patients with values above the median, PCb was associated with significantly longer RFS compared with CEF-T (Figure 2A hazard ratio [HR] = 0.30, 95% confidence interval [CI] 0.09-0.95, p = 0.03), while no evidence of different efficacy was found in the patients with lower HRD scores (Figure 2B HR = 1.53, 95% CI 0.59-3.96, p = 0.38). Consistently, within the PCb cohort, patients with HRD score above the median had a borderline significantly better RFS than the rest (HR = 0.36, 95% CI 0.11-1.19, p = 0.08), while no significant difference in RFS was detected in the CEF-T cohort (HR = 1.81, 95% CI 0.72-4.53, p = 0.20).
Although HRD is reversible, mutational signatures would not disappear, even if the defect is no longer active. Patients were also sorted by their HRD-related mutational signature value regardless of the regimen. There was a borderline significant difference in RFS between the PCb arm and the CEF-T arm in patients whose values were above the median (Figure 2C HR = 0.26, 95% CI 0.06-1.20, p = 0.06), while the outcome of the two cohorts was similar in the rest (Figure 2D HR = 0.97, 95% CI 0.31-3.04, p = 0.96). No significant difference in RFS was observed between the patients with values above the median and patients with values below the median in the PCb cohort (HR = 0.39, 95% CI 0.08-1.95, p = 0.24) or the CEF-T cohort (HR = 1.61, 95% CI 0.56-4.63, p = 0.37).
Additionally, we also investigated the predictive effect of the intrinsic subtype and the FUSCC subtype. Multivariate analyses based on HRD score and HRD-related mutational signature were also conducted, and the results were consistent with the univariate analysis (Table S3).
Furthermore, taking advantage of the RNA sequencing data, we found a couple of hypoxia and glycolysis-related pathways associated with inferior prognosis in the CEF-T cohort (Figure 3A). This finding was validated in the TNBC patients who received chemotherapy in METABRIC (Figure 3B). Moreover, upregulation of the gene set variation analysis score of Reactome glycolysis, a representative pathway regarding hypoxia and glycolysis, predicted inferior RFS in patients receiving CEF-T (Figure 3C, left, HR = 3.43, 95% CI 1.37-8.60, p = 0.01), but not in those receiving PCb (Figure 3C, middle, HR = 0.47, 95% CI 0.10-2.23, p = 0.33). Association of Reactome glycolysis with worse RFS was also validated in the TNBC patients who received chemotherapy in METABRIC (Figure 3C, right, HR = 1.72, 95% CI 1.08-2.73, p = 0.02).
Association between upregulation of glycolysis and hypoxia-related pathways and inferior prognosis in the CEF-T cohort was observed, and similar results were validated in METABRIC. Metabolic reprogramming is a major hallmark of tumor cells, and chemotherapy-resistant TNBC cells usually display an enhanced glycolytic phenotype. Our findings suggest that tumor cells are possible to develop resistance to anthracycline/taxane regimen through transforming their expression of metabolic pathways. Thus, application of glycolytic inhibitors could become a potential treatment strategy to adopt.
In conclusion, the HRD score may serve as a biomarker to predict the efficacy of an adjuvant carboplatin-containing regimen for TNBC. Upregulation of glycolysis and hypoxia-related pathways was associated with inferior prognosis of patients treated by adjuvant anthracycline/taxane regimen. Whether metabolic alterations participate in resistance needs to be further studied, and relevant treatment strategies are worth exploring.
PMID: 34586725
DOI: 10.1002/ctm2.513