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SECTION IV: Biological Markers, Genetic Expression

Abstract 213
Biological Markers with Predictive Value in Metastatic Breast Cancer Patients Randomly Treated with Doxorubicin (A) or Docetaxel (D)
Angelo Di Leo, MD, PhD, Jules Bordet Institute, Brussels, Belgium

This substudy of the TAX 303 trial suggests that Taxotere (docetaxel) is more effective than doxorubicin (Adriamycin, Adiblastine, Adriablatina, Doxil, and others) in patients with metastatic breast cancer overexpressing human epidermal growth factor receptor-2 (HER-2), while both treatments appear to have similar efficacy in HER-2-negative breast cancer patients. A larger prospective trial is needed to confirm these results, noted Dr. Angelo Di Leo during a presentation at the 38^th annual ASCO meeting.

TAX 303, which included 326 patients, demonstrated that single-agent Taxotere achieved a superior response rate compared with single-agent doxorubicin (Chan S et al. J Clin Oncol 1999;17(8):2341-2354). To date, no significant differences between the two agents have been found for time to progression and overall survival.

Trial Design
Dr. Di Leo's team evaluated archival primary tumor samples from 176 patients entered in TAX 303; 85 had been randomized to single-agent Taxotere and 91 to single-agent doxorubicin.

Results
Thirty-six (20%) patients were HER-2-positive — 21 (25%) of the Taxotere group and 15 (16%) of the doxorubicin group.

Overall, 113 (64%) patients were HER-2-negative — 50 (59%) in the Taxotere group and 63 (69%) in the doxorubicin group. HER-2 status remained unknown in 27 (15%) patients — 14 (16%) in the Taxotere group and 13 (15%) in the doxorubicin group.

In this subgroup of patients, a 46% response rate was found for those on Taxotere and 33% for those on doxorubicin. Median time to progression was six months with Taxotere and 5.7 months with doxorubicin. Median overall survival was 14 months and 14.7 months, respectively.

Overall response rates for HER-2-positive patients favored Taxotere — 67% vs. 27%, respectively (p=0.04). Overall response rates in HER-2-negative patients were similar for the two treatment arms — 40% for Taxotere and 35% for doxorubicin. Median time to progression and median overall survival were similar between the two groups (Table 5).

Table 5. Biological Markers with Predictive Value in Metastatic Breast Cancer

Table 5. Biological Markers with Predictive Value in Metastatic Breast Cancer

Source: Adapted from Angelo Di Leo, MD, as presented at the 38^th Annual Meeting of the American Society of Clinical Oncology (ASCO), May 18-21, 2002, Orlando, Florida. Abstract 213.

The researchers are also studying other biological markers — tau protein, alpha and beta tubulin, and beta tubulin isotypes.

Key Points In Focus:

The TAX 303 study showed single-agent Taxotere achieves a superior response rate compared with doxorubicin in patients with metastatic breast cancer.
The substudy of TAX 303 suggests that Taxotere is more effective than doxorubicin in HER-2-positive patients with metastatic breast cancer. Both treatments appear to have similar efficacy in HER-2-negative breast cancer.

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