Loss of HER2 positivity and prognosis after neoadjuvant therapy in HER2-positive breast cancer patients

Prospective Biomarker Analysis of the Randomized CHER-LOB Study Evaluating the Dual Anti-HER2 Treatment With Trastuzumab and Lapatinib Plus Chemotherapy as Neoadjuvant Therapy for HER2-Positive Breast Cancer

BACKGROUND

The CHER-LOB randomized phase II study showed that the combination of lapatinib and trastuzumab plus chemotherapy increases the pathologic complete remission (pCR) rate compared with chemotherapy plus either trastuzumab or lapatinib. A biomarker program was prospectively planned to identify potential predictors of sensitivity to different treatments and to evaluate treatment effect on tumor biomarkers.

MATERIALS AND METHODS

Overall, 121 breast cancer patients positive for human epidermal growth factor 2 (HER2) were randomly assigned to neoadjuvant chemotherapy plus trastuzumab, lapatinib, or both trastuzumab and lapatinib. Pre- and post-treatment samples were centrally evaluated for HER2, p95-HER2, phosphorylated AKT (pAKT), phosphatase and tensin homolog, Ki67, apoptosis, and PIK3CA mutations. Fresh-frozen tissue samples were collected for genomic analyses.

RESULTS

A mutation in PIK3CA exon 20 or 9 was documented in 20% of cases. Overall, the pCR rates were similar in PIK3CA wild-type and PIK3CA-mutated patients (33.3% vs. 22.7%; p = .323). For patients receiving trastuzumab plus lapatinib, the probability of pCR was higher in PIK3CA wild-type tumors (48.4% vs. 12.5%; p = .06). Ki67, pAKT, and apoptosis measured on the residual disease were significantly reduced from baseline. The degree of Ki67 inhibition was significantly higher in patients receiving the dual anti-HER2 blockade. The integrated analysis of gene expression and copy number data demonstrated that a 50-gene signature specifically predicted the lapatinib-induced pCR.

CONCLUSION

PIK3CA mutations seem to identify patients who are less likely to benefit from dual anti-HER2 inhibition. p95-HER2 and markers of phosphoinositide 3-kinase pathway deregulation are not confirmed as markers of different sensitivity to trastuzumab or lapatinib.

IMPLICATIONS FOR PRACTICE

HER2 is currently the only validated marker to select breast cancer patients for anti-HER2 treatment; however, it is becoming evident that HER2-positive breast cancer is a heterogeneous disease. In addition, more and more new anti-HER2 treatments are becoming available. There is a need to identify markers of sensitivity to different treatments to move in the direction of treatment personalization. This study identified PIK3CA mutations as a potential predictive marker of resistance to dual anti-HER2 treatment that should be further studied in breast cancer.

Life-threatening metastasis was suppressed by trastuzumab containing regimen in a patient with Her2-negative breast cancer

A 49-year-old female was referred to our hospital with left breast cancer and subsequently underwent mastectomy and axillary dissection. The pathological findings showed invasive breast cancer with lymph node metastasis (2/22), nuclear grade 3, ER (6+) PgR (2+) for the Allred score, and Her2 (2+) in an immunohistochemistry. We determined the subtype of Her2-negative breast cancer according to the fluorescent in situ hybridization results, as follows: Her2/CEP17 ratio 1.1 < 2.0. The patient received the EC regimen followed by docetaxel, and toremifene was subsequently administered. One year after the operation, the CA15-3 level was elevated at 50 ng/ml, and CT revealed liver metastases. Disease progression was not suppressed by paclitaxel containing regimen and eribulin. Then, we subsequently sought to determine whether the metastatic lesion showed the Her2 expression. Although the Her2 expression in the axillary lymph node metastases showed heterogeneous staining, the results were judged as Her2 (1+) according to the ASCO/CAP guidelines. We decided to administer trastuzumab and docetaxel due to the patient's life-threatening status, after which the CA15-3 level decreased and the symptom of fatigue improved. A total of 9 cycles of trastuzumab and docetaxel were administered, followed by maintenance trastuzumab continued to the present time. Physicians should be aware of the statement in the ASCO/CAP guidelines that the clinical decision to ultimately consider Her2-targeted therapy should be individualized according to the patient's status.

Loss of HER2 Positivity after Trastuzumab in HER2-Positive Gastric Cancer: Is Change in HER2 Status Significantly Frequent?

Trastuzumab has recently been introduced as a treatment for HER2-positive metastatic and/or unresectable gastric cancer (MUGC); however, compared with breast cancer, some issues concerning HER2 and trastuzumab therapy for gastric cancer remain unclear. A 74-year-old woman received trastuzumab-containing chemotherapy for HER2-positive MUGC. She had a marked response to 8 months of chemotherapy, and gastrectomy and hepatic metastasectomy with curative intent were performed. The resected specimen showed complete loss of HER2 positivity in the residual tumor. For MUGC, a change in HER2 status during the course of the disease with or without chemotherapy has rarely been reported. However, in breast cancer, a significant frequency of change in HER2 status during the course of disease has been reported, and reevaluation of HER2 positivity in metastatic/recurrent sites is recommended. The choice of trastuzumab for MUGC is currently based on the HER2 status of the primary tumor at the time of initial diagnosis, without reassessment of HER2 status during the course of disease and/or in metastatic/recurrent sites, on the assumption that HER2 status is stable. However, our case casts doubt on the stability of HER2 in gastric cancer.

Macroscopic handling and reporting of breast cancer specimens pre- and post-neoadjuvant chemotherapy treatment: review of pathological issues and suggested approaches

Neoadjuvant chemotherapy (NACT) is used increasingly in the treatment of invasive breast cancer and presents challenges for the pathologist in the handling and interpretation of tissues. Potential issues include pathological identification and localization of the residual tumour site; how best to assess pathological response (given the diversity of scoring systems described); the timing and assessment of axillary node biopsy; and the value of retesting any residual tumour for dissonance between core biopsy and post-treatment residual cancer cells for biomarker expression such as oestrogen and progesterone receptors and human epidermal growth factor receptor 2 (HER2). The role of the pathologist is critical in modern NACT approaches to breast cancer and is likely to remain challenging as novel agents and newer biomarkers become available. In this manuscript we review these issues and describe some practical approaches to handling and reporting these samples in the routine histopathology laboratory.

Decreased ERCC1 Expression After Platinum-Based Neoadjuvant Chemotherapy in non-Small Cell Lung Cancer

We have already demonstrated in a small cohort of 17 non-small cell lung cancer patients that ERCC1 (excision repair cross-complementation group 1) protein expression decreased after platinum-based treatment, however, certain clinicopathological parameters, such as histologic subtypes, ERCC1 expression scores, chemotherapeutic combinations, response rate, gender and smoking history were not analyzed. The aim of our present study was to extend the studied cohort and analyze those parameters. ERCC1 protein expression was examined in 46 patients treated with neoadjuvant chemotherapy. 46 bronchoscopic biopsy samples (27 squamous cell carcinomas /SCC/ and 19 adenocarcinomas /ADC/) together with their corresponding surgical biopsies were studied. ERCC1 immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissues. Staining scores were calculated by multiplying the percentage of positive tumor cells (0-100) by the staining intensity (0-3). 24/27 bronchoscopic SCC tissues expressed ERCC1. Thirteen of these cases became negative after neoadjuvant therapy and the expression differences between pre- and postchemotherapy samples were highly significant (p < 0.001). 11/19 bronchoscopic ADC tissues expressed ERCC1. Six of these cases became negative after neoadjuvant therapy and the expression differences were significant (p < 0.010). There was no newly expressed ERCC1 postoperatively. Comparison of staining score changes revealed more pronounced decrease in SCC (p = 0.032). We observed no correlation between initial ERCC1 level or ERCC1 decrease and overall survival, but we demonstrated correlations between decrease in ERCC1 expression and histologic subtypes of tumors and gender. We could confirm our previous data in a larger cohort that platinum-based chemotherapy affects the ERCC1 expression probably referring to an induction of tumor cell selection.

Clinical impact of c-MET expression and genetic mutational status in colorectal cancer patients after liver resection

c-MET is implicated in the pathogenesis and growth of a wide variety of human malignancies, including colorectal cancer (CRC). The aim of the present study was to clarify the association between c-MET expression and tumor recurrence in CRC patients after curative liver resection, and to evaluate concordance in c-MET expression and various mutations of KRAS, BRAF and PIK3CA between primary CRC and paired liver metastases. A cohort of patients was tested for c-MET immunoreactivity (i.e. immunohistochemistry [IHC]) and KRAS, BRAF and PIK3CA mutations. Analyses were performed both on primary tumors and paired liver metastases, and the association between IHC and mutations results were assessed. A total of 108 patients were eligible. A total of 53% of patients underwent simultaneous resection of primary tumors and metastases, and the others underwent metachronous resection. Levels of concordance between primary tumors and metastases were 65.7%, 87.7%, 100% and 95.2% for c-MET, KRAS, BRAF and PIK3CA, respectively. High levels of c-MET expression (c-MET-high) in the primary tumors were observed in 52% of patients. Relapse-free survival was significantly shorter for patients with c-MET-high primary tumors (9.7 months) than for those with c-MET-low primary tumors (21.1 months) (P = 0.013). These results suggest that a high level of genetic concordance in KRAS, BRAF and PIK3CA between primary tumors and liver metastases, and c-MET-high in the primary tumors were associated with shorter relapse-free survival after hepatic metastasectomy.