First-line bevacizumab plus paclitaxel in Japanese patients with HER2-negative metastatic breast cancer: subgroup results from the randomized Phase III MERiDiAN trial.

BACKGROUND: In the double-blind placebo-controlled randomized Phase III MERiDiAN trial (ClinicalTrials.gov NCT01663727), adding bevacizumab to paclitaxel for HER2-negative metastatic breast cancer (mBC) significantly improved progression-free survival (PFS; stratified hazard ratio [HR] 0.68, 99% confidence interval [CI], 0.51-0.91). We assessed the efficacy and tolerability of first-line bevacizumab-paclitaxel in the subset of Japanese patients in MERiDiAN. METHODS: Eligible patients had HER2-negative mBC previously untreated with chemotherapy. Plasma vascular endothelial growth factor (VEGF)-A was measured before randomization to paclitaxel 90 mg/m2 on Days 1, 8 and 15 with either placebo or bevacizumab 10 mg/kg on Days 1 and 15, repeated every 4 weeks until disease progression, unacceptable toxicity or consent withdrawal. Stratification factors were: baseline plasma VEGF-A level, prior adjuvant chemotherapy, hormone receptor status and geographic region. Co-primary endpoints were investigator-assessed PFS in the intent-to-treat (ITT) population and in the subgroup with high plasma VEGF-A. This exploratory analysis evaluated efficacy and safety in the subpopulation treated in Japanese centers. RESULTS: Of 481 patients randomized in MERiDiAN, 54 (11%) were Japanese. The stratified PFS HR in the Japanese subgroup was 0.64 (95% CI, 0.29-1.40). Median PFS was 9.2 months with placebo-paclitaxel (n = 30) versus 12.7 months with bevacizumab-paclitaxel (n = 24). Bevacizumab was associated with increased incidences of Grade ≥3 neutropenia, peripheral sensory neuropathy and hypertension, but there was no Grade ≥3 proteinuria, bleeding or gastrointestinal perforation. CONCLUSIONS: Bevacizumab-paclitaxel efficacy in Japanese patients was consistent with the MERiDiAN ITT population. No new safety signals were seen and tolerability was consistent with previous experience.

A multicenter Phase II study evaluating the efficacy, safety and pharmacokinetics of trastuzumab emtansine in Japanese patients with heavily pretreated HER2-positive locally recurrent or metastatic breast cancer.

OBJECTIVE: Trastuzumab emtansine significantly improved progression-free survival and overall survival when compared with lapatinib-capecitabine in pretreated human epidermal growth factor receptor 2-positive advanced breast cancer. However, data in Japanese populations are limited. METHODS: In the single-arm Phase II JO22997 study, Japanese patients with human epidermal growth factor receptor 2-positive inoperable locally advanced/recurrent or metastatic breast cancer previously treated with at least one prior chemotherapy regimen for locally advanced/recurrent or metastatic breast cancer and trastuzumab in any setting received 3.6 mg/kg trastuzumab emtansine every 3 weeks until progression, unacceptable toxicity or consent withdrawal. The primary endpoint was Independent Review Committee-assessed objective response rate. Secondary endpoints included progression-free survival, overall survival, safety and pharmacokinetics. RESULTS: The objective response rate in 73 treated patients was 38.4% (90% confidence interval, 28.8-48.6%), exceeding the prespecified boundary for an objective response rate > 20%. After 6.5 months' median follow-up, median progression-free survival was 5.6 months (95% confidence interval, 4.6-8.2). After 28.9 months' median follow-up, median overall survival was 30.5 months (95% confidence interval 25.2-not reached). There were no treatment-related deaths. The most common Grade 3/4 adverse events were thrombocytopenia (22%) and aspartate aminotransferase elevations (14%). Thrombocytopenia did not require platelet transfusion and typically recovered before the next cycle. There were no substantial differences in trastuzumab emtansine or trastuzumab pharmacokinetic parameters between this study and previous data from non-Japanese patients. CONCLUSIONS: JO22997 results suggest high activity of trastuzumab emtansine in Japanese patients, a safety profile consistent with previous studies in non-Japanese patients, no new safety signals and no evidence of pharmacokinetic differences between Japanese and non-Japanese populations. These results support trastuzumab emtansine therapy for Japanese patients with chemotherapy- and trastuzumab-pretreated human epidermal growth factor receptor 2-positive locally advanced/recurrent or metastatic breast cancer.

Trastuzumab emtansine plus pertuzumab in Japanese patients with HER2-positive metastatic breast cancer: a phase Ib study.

PURPOSE: To investigate the safety, pharmacokinetics, and efficacy of trastuzumab emtansine (T-DM1) in combination with pertuzumab in Japanese patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. PATIENTS AND METHODS: Patients with HER2-positive advanced or recurrent breast cancer who had received trastuzumab and chemotherapy-containing therapies were eligible. Patients received T-DM1 (3.6 mg/kg) with full-dose pertuzumab (a loading dose of 840 mg and then 420 mg) intravenously every 3 weeks. This study was registered at the Japan Pharmaceutical Information Center-Clinical Trials Information (JapicCTI-101234). RESULTS: Six patients enrolled in this study. The median duration of treatment was 11 (range 1-32) cycles. The most common treatment-emergent adverse event (TEAE) for any grade was diarrhea. Grade 3 or greater TEAEs included aspartate aminotransferase increased, left ventricular ejection fraction (LVEF) decreased, and neutrophil count decreased. The dose-limiting toxicity of grade 3 LVEF decreased was observed in one patient during cycle 1; however, it resolved within 30 days. The pharmacokinetic parameters of T-DM1 and pertuzumab were not affected by co-administration of the drugs. The best overall response included a partial response (PR) in 3 patients (50%) and stable disease (SD) in 2 patients (33%). CONCLUSIONS: The combination of T-DM1 and pertuzumab was tolerated and showed exploratory efficacy in Japanese patients with HER2-positive metastatic breast cancer.

Safety Evaluation of Trastuzumab Emtansine in Japanese Patients with HER2-Positive Advanced Breast Cancer.

BACKGROUND/AIM: Tolerability and safety of trastuzumab emtansine (T-DM1) was investigated in Japanese patients with HER2-positive advanced breast cancer who were previously treated with chemotherapy and trastuzumab. PATIENTS AND METHODS: Patients with inoperable or recurrent breast cancer who were previously treated with chemotherapy and trastuzumab in adjuvant and/or metastatic disease were included. T-DM1 3.6 mg/kg was administered intravenously every 21 days. The administration dosage or schedule of T-DM1 was modified based on laboratory tests on the administration day. RESULTS: Among 232 patients analyzed, adverse events were reported in 228 patients (98.3%); five patients (2.2%) discontinued due to adverse events and twenty patients (8.6%) had serious adverse events. The most commonly reported grade ≥3 adverse event of special interest was thrombocytopenia (69 patients; 29.7%), followed by hepatotoxicity (26 patients; 11.2%). CONCLUSION: T-DM1 was well tolerated in Japanese patients with HER2-positive advanced breast cancer and no new safety signals were observed.

Involvement of novel protein kinase C isoforms in carbachol-stimulated insulin secretion from rat pancreatic islets.

The roles of protein kinase C (PKC) isoforms in cholinergic potentiation of glucose-induced insulin secretion were investigated in rat pancreatic islets. Western-blot analysis showed the presence of PKC-alpha, betaII, delta, epsilon, eta, and zeta, but not PKC-betaI, gamma, or iota, in the islets. Carbachol (CCh) caused translocations of PKC-alpha, betaII, delta, and epsilon from the cytosol to the plasma membrane. CCh facilitated 7-mM glucose-induced insulin secretion from isolated rat islets. The CCh-stimulated insulin secretion was significantly suppressed by the generic PKC inhibitor chelerythrine. In contrast, Go 6976, an inhibitor of conventional PKC isoforms, had no effect on the insulin secretion stimulated by CCh, although it significantly inhibited that induced by phorbol 12-myristate 13-acetate. These results suggest that the novel PKC isoforms activated by CCh, i.e., PKC-delta and/or epsilon, participate in the stimulatory effect of CCh on insulin secretion.

Involvement of stretch-activated cation channels in hypotonically induced insulin secretion in rat pancreatic beta-cells.

In isolated rat pancreatic beta-cells, hypotonic stimulation elicited an increase in cytosolic Ca(2+) concentration ([Ca(2+)](c)) at 2.8 mM glucose. The hypotonically induced [Ca(2+)](c) elevation was significantly suppressed by nicardipine, a voltage-dependent Ca(2+) channel blocker, and by Gd(3+), amiloride, 2-aminoethoxydiphenylborate, and ruthenium red, all cation channel blockers. In contrast, the [Ca(2+)](c) elevation was not inhibited by suramin, a P(2) purinoceptor antagonist. Whole cell patch-clamp analyses showed that hypotonic stimulation induced membrane depolarization of beta-cells and produced outwardly rectifying cation currents; Gd(3+) inhibited both responses. Hypotonic stimulation also increased insulin secretion from isolated rat islets, and Gd(3+) significantly suppressed this secretion. Together, these results suggest that osmotic cell swelling activates cation channels in rat pancreatic beta-cells, thereby causing membrane depolarization and subsequent activation of voltage-dependent Ca(2+) channels and thus elevating insulin secretion.