Abstract
Purpose: Suberoylanilide hydroxamic acid (SAHA; vorinostat), a small molecule inhibitor of histone deacetylase, attenuates signaling pathways known to confer trastuzumab resistance. A combination of SAHA and trastuzumab may be a promising strategy to improve the efficacy of trastuzumab against breast cancer. In this Phase I/II study, we evaluated the toxicity and response rate after treatment with SAHA and trastuzumab in patients with HER2-overexpressing metastatic breast cancer with trastuzumab-resistant progressive disease. Methods: In Phase I, the SAHA dose was modified in cohorts of 3–6 patients to find the dose level at which 0 or 1 patients experienced a dose-limiting toxicity (DLT) during the first cycle of therapy. In the Phase II study, response to the recommended dose identified in Phase I was based on the response evaluation criteria in solid tumors. Overall survival and time to progression were also evaluated. Results: The recommended dose was determined to be 200 mg twice a day on days 1–14 and IV trastuzumab 6 mg/kg on day 1 of a 21-day cycle (n = 6). The Phase II study (n = 10) was terminated when the pre-planned efficacy evaluation found that none of the patients in the primary analysis set responded to combination SAHA and trastuzumab treatment. Conclusions: In patients with HER2-positive metastatic breast cancer who had relapsed or progressed during trastuzumab therapy, we observed no DLTs with SAHA 200 mg twice daily combined with trastuzumab; however, there was insufficient statistical evidence that adding SAHA reversed trastuzumab resistance in these patients.
Original language | English (US) |
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Pages (from-to) | 375-382 |
Number of pages | 8 |
Journal | Breast Cancer Research and Treatment |
Volume | 165 |
Issue number | 2 |
DOIs | |
State | Published - Sep 1 2017 |
Keywords
- Anticancer therapy
- Histone deacetylase
- Resistance
- Toxicity
- Tumor
ASJC Scopus subject areas
- Oncology
- Cancer Research