my personal edition > breast cancer > news


  E-Mail this DGDispatch to a colleague

DGDispatch

Phase 3 Trial Shows Advantages of Exemestane Over Tamoxifen in Metastatic Breast Cancer: Presented at EBCC

By Paula Moyer

HAMBURG, GERMANY -- March 22, 2004 -- The first head-to-head trial comparing an aromatase inhibitor to tamoxifen shows that exemestane may offer advantages in hormone-responsive metastatic breast cancer, according to findings presented here March 18^th at the 4^th European Breast Cancer Conference.

"We saw a significant improvement over tamoxifen, with results that are comparable to anastrazole," said principal investigator Dr. Robert Paridaens, a medical oncologist at the University Hospital Gasthuisberg in Leuven, Belgium. "Exemestane appears to have better tolerability and efficacy than tamoxifen."

The investigators were interested in determining exemestane's potential because of recent data showing that nonsteroidal aromatase inhibitors, such as anastrazole and letrozole, were at least as – if not more – active than tamoxifen, and that this drug class may have a more favourable toxicity profile. Exemestane differs from other aromatase inhibitors because it is the only such drug with a steroidal structure and it permanently inactivates aromatase. Unlike nonsteroidal versions, it is not associated with cross-resistance with others in the class.

Therefore, the European Organisation for Research and Treatment of Cancer Breast Group began a randomised phase 2-3 clinical trial in 1996 that sought to compare the efficacy and safety of exemestane versus tamoxifen.

Patients with measurable disease were eligible if they had received no prior hormone therapy for metastatic breast cancer and had either a hormone receptor-positive cancer, or an unknown status with a long disease-free interval.

Patients were randomised in open-label fashion to tamoxifen at a dose of 20 mg daily or to exemestane at a dose of 25 mg daily. The study endpoint of the phase 2 trial was activity; during the phase 3 trial, the primary endpoint was efficacy, which the investigators defined as progression-free survival. The goal was to determine whether exemestane-treated patients had a median progression-free survival increase of 3 months over tamoxifen. The secondary endpoint in both trials was safety. Between the initial recruitment in October 1996 and July 2002, the investigators recruited 382 patients from 81 institutions in 25 different countries, with 190 in the exemestane group and 192 in the tamoxifen group.

Among the patients in the exemestane group, 14 (7%) had a complete response to treatment, and 71 (37%) had a partial response. In the tamoxifen group, 5 (3%) had a complete response and 52 (17%) had a partial response. "Regardless of the site of metastasis, we saw more response in the exemestane group than in the tamoxifen group," Dr. Paridaens said.

The average length of progression-free survival was 9.95 months in the exemestane group and 5.72 months in the tamoxifen group. Among all of the patients, 284 (74%) have either experienced progression or have died. The investigators are still assessing the overall survival data and will release their findings later in 2004.


[Study title: First results of a randomized phase III trial comparing exemestane versus tamoxifen as first-line hormone therapy (HT) for postmenopausal women with metastatic breast cancer (MBC) – EORTC 10951 in collaboration with the exemestane working group and NCIC Clinical Trials Group. Abstract 241]

E-Mail this DGDispatch to a colleague

To print, use this version