Efficacy of neoadjuvant Cisplatin in triple-negative breast cancer

Abstract

PURPOSE Cisplatin is a chemotherapeutic agent not used routinely for breast cancer treatment. As a DNA cross-linking agent, cisplatin may be effective treatment for hereditary BRCA1-mutated breast cancers. Because sporadic triple-negative breast cancer (TNBC) and BRCA1-associated breast cancer share features suggesting common pathogenesis, we conducted a neoadjuvant trial of cisplatin in TNBC and explored specific biomarkers to identify predictors of response. PATIENTS AND METHODS Twenty-eight women with stage II or III breast cancers lacking estrogen and progesterone receptors and HER2/Neu (TNBC) were enrolled and treated with four cycles of cisplatin at 75 mg/m(2) every 21 days. After definitive surgery, patients received standard adjuvant chemotherapy and radiation therapy per their treating physicians. Clinical and pathologic treatment response were assessed, and pretreatment tumor samples were evaluated for selected biomarkers. Results Six (22%) of 28 patients achieved pathologic complete responses, including both patients with BRCA1 germline mutations;18 (64%) patients had a clinical complete or partial response. Fourteen (50%) patients showed good pathologic responses (Miller-Payne score of 3, 4, or 5), 10 had minor responses (Miller-Payne score of 1 or 2), and four (14%) progressed. All TNBCs clustered with reference basal-like tumors by hierarchical clustering. Factors associated with good cisplatin response include young age (P = .001), low BRCA1 mRNA expression (P = .03), BRCA1 promoter methylation (P = .04), p53 nonsense or frameshift mutations (P = .01), and a gene expression signature of E2F3 activation (P = .03). CONCLUSION Single-agent cisplatin induced response in a subset of patients with TNBC. Decreased BRCA1 expression may identify subsets of TNBCs that are cisplatin sensitive. Other biomarkers show promise in predicting cisplatin response.

Fig 1.

Predictors of response to cisplatin therapy in triple-negative basal-like tumors. (A) The sample dendrogram of gene expression hierarchical cluster analysis with the intrinsic genes is shown. Cisplatin pretreatment samples (sample numbers in red) are co-clustered with a reference set of breast tumors (sample numbers in black). Intrinsic subtype of the reference cases, determined by an independent hierarchical cluster analysis, is indicated by the color bar below the dendrogram as follows: luminal A, dark blue; luminal B, light blue; ErbB2, green; normal-like, purple; basal-like, red. Cisplatin response of the trial patients is indicated on the lower row as follows: resistant (progression, Miller-Payne score of 1 or 2) in gray; sensitive (Miller-Payne score of 3, 4, or 5) in black. (*) Trial cases with pathologic complete response (pCR; Miller-Payne score of 5). (B) Relationship of BRCA1 biomarkers and p53 family biomarkers to cisplatin sensitivity. Each trial patient is indicated by sample number, and patients are arranged according to relative response to cisplatin chemotherapy. Progression or Miller-Payne response scores are indicated above each sample. Predictive biomarker positivity is indicated with solid circles as follows: i = the presence of a BRCA1 germline mutation, ii = the lowest quartile of BRCA1 mRNA expression measured by quantitative reverse transcriptase polymerase chain reaction, iii = the presence of BRCA1 promoter methylation, iv = the ratio of mRNA expression levels of ΔNp63/TAp73 measured by quantitative reverse transcriptase polymerase chain reaction > 2, and v = the presence of p53 protein-truncating mutations. For each biomarker, samples with no data are indicated by a gray X; in addition, for BRCA1 mRNA expression and promoter methylation, a gray X indicates “not applicable” for the two cases with known BRCA1 germline mutation. NSM, nonsense or frameshift mutations.

Fig 2.

Relationship of cisplatin treatment response to clinical and molecular features. (A) The patient age in years (y-axis) and Miller-Payne pathologic response score to neoadjuvant cisplatin therapy (x-axis) are plotted for each patient in the cohort as indicated by solid circles (P = .001 based on ordered quartiles of age). (B) Relative BRCA1 mRNA level measured by quantitative reverse transcriptase polymerase chain reaction (PCR; 2^−ΔΔCT) is plotted for resistant tumors (solid circles) and sensitive tumors (open circles). The average mRNA level of each group is indicated by a black horizontal line. Measurements were performed using PCR primer pairs encompassing exons 1 and 2 (E1/E2), exons 16 and 17 (E16/E17), and exons 19 and 20 (E19/E20) as indicated along the bottom of the plot. The Wilcoxon P values for difference between sensitive and resistant tumors are indicated above each primer pair as follows: (***) P = .020; (**) P = .048; (*) P = .098. (C) Electrophoresis of PCR products spanning the BRCA1 promoter from bisulfite-treated DNA. Each lane contains products generated from separate PCR reactions using primers specific for methylated (m) or unmethylated (u) DNA template. Bacterial methylase-treated lymphocyte DNA was used for the positive control (+). DNA from normal lymphocytes was used as a negative control (−). The lane marked MW indicates molecular weight markers measured in base pairs (bp). Paired methylated- and unmethylated-specific primer reactions are marked by a line over the paired lanes and labeled corresponding to the template DNA used in the reaction (positive control, negative control, and patient No.). Patients 17 and 23 demonstrate bands in both the unmethylated (u) and methylated (m) lanes indicating the presence of BRCA1 promoter methylation. Patients 16, 20, 21, 22, and 24 lack bands with the methylated primer pair, signifying the absence of BRCA1 promoter methylation. (D) The E2F3 signature score (y-axis) and Miller-Payne pathologic response scores (x-axis) plotted (solid circles) for each patient in the cohort with available gene expression array data (Pearson correlation, 0.46; P = .025).