Weekly paclitaxel with trastuzumab and pertuzumab in patients with HER2-overexpressing metastatic breast cancer: overall survival and updated progression-free survival results from a phase II study.

We previously reported progression-free survival (PFS) results on a phase II trial of weekly paclitaxel, trastuzumab, and pertuzumab in patients with human epidermal growth factor receptor 2(HER2)-positive metastatic breast cancer (MBC) treated in the first- and second-line setting. Here, we report results for overall survival (OS) and updated PFS after an additional year of follow-up. Patients with HER2-positive MBC with 0-1 prior treatment were eligible. Treatment consisted of paclitaxel (80 mg/m(2)) weekly, and trastuzumab (loading dose 8 mg/kg â†’ 6 mg/kg) and pertuzumab (loading dose 840 mg â†’ 420 mg) every 3 weeks, all given intravenously. Primary endpoint was 6-month PFS. Secondary endpoints included median PFS, 6-month and median OS. Evaluable patients received at least one full dose of treatment. From January 2011 to December 2013, 69 patients were enrolled: 51 (74 %) and 18 (26 %) treated in first- and second-line metastatic settings, respectively. As of July 1, 2015, the median follow-up was 33 months (range 3-49 months; 67 patients were evaluable for efficacy). The median OS was 44 months (95 % CI 37.5-NR) overall and 44 months (95 % CI 38.3-NR) and 37.5 months (95 % CI 30.3-NR) for patients with 0 and 1 prior metastatic treatment, respectively; 6-month OS was 98 % (95 % CI 90-1). The 6-month PFS was 86 % (95 % CI 75-93) overall and 89 % (95 % CI 76-95) and 78 % (95 % CI 51-91) for patients with 0 and 1 prior therapy, respectively; and median PFS was 21.4 months (95 % CI 14.1-NR) overall and 25.7 months (95 % CI 14.1-NR) and 16.9 months (95 % CI 8.5-NR) for patients with 0-1 prior treatment, respectively. Treatment was well tolerated. Updated analysis demonstrates that weekly paclitaxel, when added to trastuzumab and pertuzumab, is associated with a favorable OS and PFS and offers an alternative to docetaxel-based therapy. http://www.ClinicalTrials.gov NCT0127604.

The histone deacetylase inhibitor suberoylanilide hydroxamic acid induces differentiation of human breast cancer cells.

Histone deacetylase (HDACs) regulate histone acetylation by catalyzing the removal of acetyl groups on the NH(2)-terminal lysine residues of the core nucleosomal histones. Modulation of the acetylation status of core histones is involved in the regulation of the transcriptional activity of certain genes. HDAC activity is generally associated with transcriptional repression. Aberrant recruitment of HDAC activity has been associated with the development of certain human cancers. We have developed a class of HDAC inhibitors, such as suberoylanilide hydroxamic acid (SAHA), that were initially identified based on their ability to induce differentiation of cultured murine erythroleukemia cells. Additional studies have demonstrated that SAHA inhibits the growth of tumors in rodents. In this study we have examined the effects of SAHA on MCF-7 human breast cancer cells. We found that SAHA causes the inhibition of proliferation, accumulation of cells in a dose-dependent manner in G(1) then G(2)-M phase of the cell cycle, and induction of milk fat globule protein, milk fat membrane globule protein, and lipid droplets. Growth inhibition was associated with morphological changes including the flattening and enlargement of the cytoplasm, and a decrease in the nuclear:cytoplasmic ratio. Withdrawal of SAHA led to reentry of cells into the cell cycle and reversal to a less differentiated phenotype. SAHA induced differentiation in the estrogen receptor-negative cell line SKBr-3 and the retinoblastoma-negative cell line MDA-468. We propose that SAHA has profound antiproliferative activity by causing these cells to undergo cell cycle arrest and differentiation that is dependent on the presence of SAHA. SAHA and other HDAC inhibitors are currently in Phase I clinical trials. These findings may impact the clinical use of these drugs.