Replication Study for the Association of Five SNPs Identified by GWAS and Trastuzumab-Induced Cardiotoxicity in Japanese and Singaporean Cohorts.

Trastuzumab (herceptin) is an effective drug for human epidermal growth factor receptor type 2 (HER2)-positive cancer. However, cardiotoxicity remains a serious complication. In our previous genome-wide association study (GWAS), we identified potential associations for five single nucleotide polymorphisms (SNPs) with trastuzumab-induced cardiotoxicity in a Japanese population. To validate this association, here we performed replication studies using Japanese and Singaporean case-control cohorts (Japan: 6 cases and 206 controls; Singapore: 22 cases and 178 controls). Although none of the SNPs showed a statistically significant association with trastuzumab-induced cardiotoxicity, we show that three (rs8032978, rs7406710 and rs9316695) and four (rs8032978, rs7406710, rs28415722 and rs11932853) SNPs had an effect in the same direction in the Japanese and the Singaporean cohort, respectively, as that in our previous study. Combining the previous study with the current replication studies, we find a strong association for two SNPs, rs8032978 and rs7406710, with trastuzumab-induced cardiotoxicity (Pcombined = 4.92 × 10-5 and 5.50 × 10-5, respectively). These data suggest that rs8032978 and rs7406710 could be predictive markers of trastuzumab-induced cardiotoxicity in Japanese and Singaporean populations, and support their potential use in clinical risk assessment. These findings offer a first step toward the development of clinically available markers for the potential risk of trastuzumab-induced cardiotoxicity as well as an improved understanding of the pathogenesis of this complication.

[Clinical Significance of the Curative Effect after Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer-Correlation to Prognosis].

We investigated factors related to the recurrence and prognosis of patients with triple-negative breast cancer (TNBC)after neoadjuvant chemotherapy(NAC). Of the 545 patients who underwent surgery after NAC between January 2013 and December 2016, 131 patients had TNBC. An analysis of each TNBC case indicated that the presence or absence of clinical lymph node metastasis(cN)before treatment might be a predictive factor of prognosis. There were 57(43.5%)pathological complete response(pCR)(ypT0 or ypTis/N0)cases after NAC. Overall survival(OS)and disease free survival(DFS) were significantly better in pCR cases than in non-pCR cases. However, recurrence was observed in 8 of 57(14%)pCR cases and 29 of 74(39%)non-pCR cases. The factors defining DFS from the univariate analysis of the non-pCR group were cN, ypT, ypN, and vascular invasion. The multivariate analysis of these factors suggested that residual cN and vascular invasion might be independent factors predicting DFS. Residual vascular invasion was found to predict OS, and was considered to be a poor prognostic factor.

A Genome-Wide Association Study Identifies Five Novel Genetic Markers for Trastuzumab-Induced Cardiotoxicity in Japanese Population.

Trastuzumab has been administered to patients with human epidermal growth factor receptor 2 (HER2)-positive cancer, however, the cardiotoxicity is identified as one of the life-threatening toxicities. Clinically useful biomarker for trastuzumab-induced cardiotoxicity has been expected to be developed. To identify a novel genetic marker(s) determining the risk of trastuzumab-induced cardiotoxicity, we performed a first genome-wide association study (GWAS) in Japanese population. We enrolled 481 patients who had been treated with trastuzumab and carried out a GWAS using 11 cases (with cardiotoxicity) and 257 controls (without cardiotoxicity). Top 100 single nucleotide polymorphisms (SNPs) which revealed the smallest p values in GWAS (p = 7.60 × 10-7 - 2.01 × 10-4) were further examined using replication samples consisted of 14 cases and 199 controls. The combined analysis of the GWAS and replication study indicated possible association of five loci with trastuzumab-induced cardiotoxicity (rs9316695 on chromosome 13q14.3, rs28415722 on chromosome 15q26.3, rs7406710 on chromosome 17q25.3, rs11932853 on chromosome 4q25, and rs8032978 on chromosome 15q26.3, Pcombined = 6.00 × 10-6, 8.88 × 10-5, 1.07 × 10-4, 1.42 × 10-4, 1.60 × 10-4, respectively). Furthermore, we developed a risk prediction model for trastuzumab-induced cardiotoxicity using the five marker SNPs. The incidence of trastuzumab-induced cardiotoxicity in patients with risk score ≥5 was significantly higher (42.5%) compared to that in patients with score ≤ 4 (1.8%) (p = 7.82 × 10-15, odds ratio = 40.0). These findings suggest the potential to improve the ability of physicians to avoid the trastuzumab-induced cardiotoxicity for patients with HER2-positive cancer.

Trastuzumab Emtansine (T-DM1) Plus S-1 in Patients with Trastuzumab-Pretreated HER2-Positive Advanced or Metastatic Breast Cancer: A Phase Ib Study.

BACKGROUND: In treating human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer, the efficacy of capecitabine combined with HER2-directed agents such as trastuzumab and lapatinib is supported by some evidence. The combination of T-DM1 and S-1, another oral 5-FU, may be a safe alternative treatment for metastatic breast cancer. OBJECTIVES: The optimal dose of S-1 was evaluated in combination with T-DM1 for patients with HER2-positive advanced or metastatic breast cancer. The safety and clinical response of this combination treatment were also assessed. METHODS: This 3 + 3 dose-escalation study of S-1 given for the first 2 of 3 weeks, in combination with T-DM1 (3.6 mg/kg given every 3 weeks) to patients with trastuzumab-pretreated HER2-positive advanced or metastatic breast cancer was designed to evaluate the dose-limiting toxicity (DLT) occurrence in the first cycle. We also evaluated the safety and clinical activity of this combination treatment in multiple cycles. Two different dose levels of S-1 (65 and 80 mg/m2/day) were planned, although the capecitabine arm was abandoned because of slow recruitment. RESULTS: Twelve out of the 13 patients enrolled were evaluable for DLT. One DLT (grade ≥3 non-hematological adverse events) occurred at dose level 0, leading to the expansion of this cohort to 6 patients, with an additional DLT (≥7 days discontinuation of medication), while no DLT occurred at dose level 1. As a result, the maximum tolerable dose of S-1 was determined to be 80 mg/m2/day for 14 days with T-DM1 3.6 mg/kg, repeated every 3 weeks. Two patients had grade 3 thrombocytopenia at dose level 0, and 1 patient at dose level 1. CONCLUSIONS: S-1 can be safely combined with the clinically relevant dose of T-DM1 in patients with HER2-positive advanced or metastatic breast cancer. Further evaluation with a larger sample size is required for efficacy assessment.

Oncologic outcomes and technical considerations of nipple-sparing mastectomies in breast cancer: experience of 425 cases from a single institution.

BACKGROUND: Nipple-sparing mastectomy (NSM) is an advantageous treatment option, providing a complete cure and good cosmetic results. We tested whether NSM is a surgically and oncologically safe technique. METHODS: We evaluated the oncological outcome of 425 breasts in 413 patients who underwent NSM between January 2000 and March 2013. We retrospectively reviewed patient data and analyzed all patient characteristics as potential risk factors of recurrence at the nipple-areola complex (NAC). To confirm the oncological safety of NSM, we compared outcomes of NSM and conventional total mastectomy. RESULTS: The median follow-up time after surgery was 46.8 months (range 6-158 months). Nipple necrosis was observed in 6 cases (1.4 %). The cumulative local recurrence rate after NSM was 5.8 % (25/425 cases), similar to that of conventional total mastectomy in the same period (5.6 %, 49/878 cases). Furthermore, the cumulative local recurrence rate at the NAC was 2.3 % (10 cases). HER2-enriched tumors and young age (<40 years) were significant risk factors for recurrence at the NAC. In patients with recurrence, the site of recurrence was easily excised, and good cosmetic results were achieved in breast reconstruction cases. CONCLUSION: NSM is safe with a low complication rate. No significant difference was observed in cumulative local recurrence rate, cumulative distant disease recurrence rate, and overall survival between patients who underwent NSM or conventional total mastectomy, confirming that NSM was surgically and oncologically safe.