TITAN: phase III study of doxorubicin/cyclophosphamide followed by ixabepilone or paclitaxel in early-stage triple-negative breast cancer.

PURPOSE: Ixabepilone is a microtubule stabilizer with activity in taxane-refractory metastatic breast cancer and low susceptibility to taxane-resistance mechanisms including multidrug-resistant phenotypes and high ß-III tubulin expression. Since these resistance mechanisms are common in triple-negative breast cancer (TNBC), ixabepilone may have particular advantages in this patient population. This study evaluated the substitution of ixabepilone for paclitaxel following doxorubicin/cyclophosphamide (AC) in the adjuvant treatment of early-stage TNBC. METHODS: Patients with operable TNBC were eligible following definitive breast surgery. Patients were randomized (1:1) to receive four cycles of AC followed by either four cycles (12 weeks) of ixabepilone or 12 weekly doses of paclitaxel. RESULTS: 614 patients were randomized: 306 to AC/ixabepilone and 308 to AC/paclitaxel. At a median follow-up of 48 months, 59 patients had relapsed (AC/ixabepilone, 29; AC/paclitaxel, 30). The median time from diagnosis to relapse was 20.8 months. The 5-year disease-free survival (DFS) rates of the two groups were similar [HR 0.92; ixabepilone 87.1% (95% CI 82.6-90.5) vs. paclitaxel 84.7% (95% CI 79.7-88.6)]. The estimated 5-year overall survival (OS) rates were also similar [HR 1.1; ixabepilone 89.7% (95% CI 85.5-92.7) vs. paclitaxel 89.6% (95% CI 85.0-92.9)]. Peripheral neuropathy was the most common grade 3/4 event. Dose reductions and treatment discontinuations occurred more frequently during paclitaxel treatment. CONCLUSIONS: Treatment with AC/ixabepilone provided similar DFS and OS in patients with operable TNBC when compared to treatment with AC/paclitaxel. The two regimens had similar toxicity, although treatment discontinuation, dose modifications, and overall peripheral neuropathy were more frequent with AC/paclitaxel. TRIAL REGISTRATION: Clinical Trials.gov Identifier, NCT00789581.

Use of a multiplexed immunoassay (PRO Onc assay) to detect HER2 abnormalities in circulating tumor cells of women with HER2-negative metastatic breast cancer: lack of response to HER2-targeted therapy.

PURPOSE: Determination of HER2 status by testing circulating tumor cells (CTCs), compared to sampling tumor biopsies, may improve patient management by allowing ongoing assessment of HER2 status during the disease course. The PRO Onc assay (Prometheus Laboratories; San Diego, CA) is a multiplexed immunoassay that measures the expression and activation of HER2 in CTCs. In this study, we screened patients with metastatic HER2-negative breast cancer with the PRO Onc assay; patients with HER2 overexpression or activation received a trial of HER2-targeted therapy. METHODS: In Part 1 of the trial, patients with HER2-negative breast cancer were screened with the PRO Onc assay to confirm the presence of a cohort that tested HER2-positive. After this finding was confirmed, patients in Part 2 of the study with HER2 abnormalities received a trial of treatment with trastuzumab/pertuzumab. RESULTS: In Part 1, 31 of 57 specimens contained CTCs; of these, 12 (38 %) showed HER2 abnormalities by PRO Onc assay. In Part 2, 129 of 226 patients (57 %) had CTCs; 24 of these patients (19 %) had HER2 abnormalities detected. Fourteen patients were treated with HER2-targeted therapy. Twelve of 14 patients progressed within 6 weeks, one patient had a brief (12 weeks) partial response, and one patient was stable for 12 weeks. CONCLUSIONS: HER2 overexpression or activation was detected by the PRO Onc assay in 22 % of HER2-negative patients with CTCs. However, HER2-targeted therapy was not effective in such patients. FISH and IHC staining remain the standards for HER2 determination.

Addition of bevacizumab to three docetaxel regimens as adjuvant therapy for early stage breast cancer.

Docetaxel-containing chemotherapy improves disease-free survival (DFS) and overall survival in patients with early stage breast cancer. Bevacizumab improves response rate and DFS in metastatic breast cancer. However, adding antivascular endothelial growth factor therapy to anthracycline-containing chemotherapy may increase cardiotoxicity. This trial evaluates the feasibility of adding bevacizumab to three standard adjuvant docetaxel regimens with a primary endpoint of grade ≥3 congestive heart failure (CHF). Phase IIb, randomized, non-comparative study of women with previously untreated node-positive or high-risk node-negative breast cancer. Human epidermal growth factor receptor 2 (HER2)-negative patients were randomized to: (arm A) doxorubicin + cyclophosphamide followed by docetaxel or (arm B) docetaxel + doxorubicin + cyclophosphamide. HER2-positive patients (arm C) received docetaxel + carboplatin + trastuzumab for 52 weeks. All patients received bevacizumab beginning on day 1 for 52 weeks. Safety data in 212 women (mean age = 53.1 years) show that 1 patient each in arm A (1.3 %) and arm C (1.7 %), and 3 patients in arm B (4.0 %) experienced clinical CHF grade ≥3. A decreased ejection fraction was observed in 1 patient each in arms A and C, and cardiac disorder was observed in 12.8, 22.7, and 8.5 % in arms A, B, and C, respectively. A grade 3/4 treatment-emergent adverse event was reported in 82.1, 84.0, and 52.5 % of participants in arms A, B, and C, respectively. Kaplan-Meier estimates of DFS show rates at 24 months of 85.5, 90.4, and 90.4 % in arms A, B, and C, respectively. Adding bevacizumab to three standard docetaxel-based chemotherapy regimens as adjuvant treatment in patients with node-positive and high-risk node-negative breast cancer resulted in a low rate of clinical CHF grade ≥3. Maintenance bevacizumab monotherapy did not identify any new safety signals. Breast cancer recurrence/relapse, secondary malignancies, and death were uncommon, although the follow-up time in this study was relatively short.

Panitumumab, Gemcitabine, and Carboplatin as Treatment for Women With Metastatic Triple-Negative Breast Cancer: A Sarah Cannon Research Institute Phase II Trial.

BACKGROUND: Triple-negative breast cancer (TNBC) is a subtype with poor prognosis, and treatment options are limited to chemotherapy. Because the epidermal growth factor receptor (EGFR) is overexpressed in up to 70% of these tumors, this phase II trial was designed to evaluate the efficacy and safety of panitumumab in combination with gemcitabine and carboplatin as first- or second-line treatment for metastatic TNBC. PATIENTS AND METHODS: Adult women with metastatic TNBC with a maximum of 1 previous chemotherapy regimen were eligible. Patients received gemcitabine intravenous (I.V.) 1500 mg/m2, carboplatin area under the concentration-time curve = 2.5 I.V., and panitumumab 6 mg/kg I.V. every 2 weeks. Treatment continued until disease progression or unacceptable toxicity, with disease evaluations every 6 weeks. The primary end point was progression-free survival (PFS). Archival tissue was collected for correlative analysis, to include phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha, p53, phosphatase and tensin homolog, EGFR, and status. RESULTS: Between May 2010 and August 2012, 71 women (median age, 54 years; 14% de novo stage IV) were treated. At a median follow-up of 11 months, the median PFS was 4.4 months (95% confidence interval, 3.2-5.5 months). The objective response rate was 42% (complete response, 1; partial response, 29). Treatment-related toxicity included: rash, 50 patients (70%), fatigue, 37 patients (52%), neutropenia, 32 patients (45%; 2 episodes of febrile neutropenia), and thrombocytopenia, 32 patients (45%). CONCLUSION: Although the addition of panitumumab was feasible, the results of this trial do not support combination of panitumumab with gemcitabine and carboplatin in the treatment of patients with TNBC.