Estrogen receptor status in the Herceptin (trastuzumab) clinical trials: Incidence and relation to clinical benefit

R. Mass, M. Cobleigh, C. Vogel, D. Slamon

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Abstract

HER2 overexpression has been reported to be inversely correlated with estrogen receptor (ER) level. Herceptin as a single agent has activity in first-and second-line treatment of metastatic breast cancer and demonstrates a significant improvement in median survival when combined with chemotherapy. Methods: 805 HER2-positive patients (defined as those with scores of 2+ or 3+ by immunohistochemistry) were enrolled in 3 clinical trials: 2 trials of Herceptin as monotherapy and 1 trial of Herceptin plus chemotherapy. We performed a retrospective analysis of outcomes in ER-positive and ER-negative patients. Because progesterone receptor (PR)-positive tumors respond to hormone therapy similarly to ER-positive tumors, ER-negative/PR-positive tumors were included with ER-positive tumors for this analysis. Results: 50% of the patients enrolled were ER positive, 40% were ER negative, and 10% had unknown ER status. Response rates (25% vs 29%) and time to progression (3.8 months vs 3.4 months) were similar for ER-positive and ER-negative patients with metastatic breast cancer treated with first-line Herceptin monotherapy. Median survival was longer for ER-positive patients (26 months vs 20 months). ER-positive and ER-negative patients with refractory metastatic breast cancer had similar response rates (16% vs 16%) and time to progression (3.2 months vs 3.0 months) when treated with Herceptin monotherapy. Median survival for ER-positive patients was slightly longer than that for ER-negative patients (14.2 months vs 12.4 months). When Herceptin was combined with chemotherapy (AC or Taxol [paclitaxel]), ER-positive and ER-negative patients had similar response rates (53% vs 49%), times to progression (6.6 months vs 7.0 months), and median survival (25.4 months vs 24.1 months). Conclusion: The data presented here support the conclusion that ER-negative/HER2-positive patients and ER-positive/HER2-positive patients have similar clinical outcomes when treated with Herceptin alone or in combination with chemotherapy. The majority of patients in these trials were ER positive; therefore, ER status should not preclude testing for HER2 status. ER status is not a predictor of benefit from Herceptin in the HER2-positive population.

Original languageEnglish (US)
Number of pages1
JournalBreast cancer research and treatment
Volume69
Issue number3
StatePublished - Jan 1 2001
Externally publishedYes

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ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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