Response-guided neoadjuvant therapy associated with better DFS, OS

San Antonio Breast Cancer Symposium

SAN ANTONIO — Interim response-guided neoadjuvant chemotherapy improved DFS and OS in patients with luminal A and B phenotypes of breast cancer, a speaker said here.

During a session, Gunter von Minckwitz, MD, of the German Breast Group, Neu-Isenburg, presented results from the Gepar-Trio phase 3 trial in which he and colleagues assigned 2,072 patients with operable or locally advanced breast cancer to one of two treatment regimens based on initial response to two cycles of docetaxel, doxorubicin and cyclophosphamide (TAC). Patients who experienced less than 50% tumor reduction, or nonresponders, were assigned to receive continuous TAC or switched to non–cross-resistant treatment (vinorelbine and capecitabine [Xeloda, Hoffmann-La Roche]). In contrast, responders, or patients who experienced more than 50% tumor reduction, received either six or eight additional TAC cycles.

After 62 months of follow-up, nonresponders receiving response-guided treatment demonstrated longer DFS (HR=0.71; 95% CI, 0.6-0.86) and OS (HR=0.79; 95% CI, 0.63-0.99) compared with responders receiving a standard six cycles of TAC. Adjusted analysis also favored the response-guided experimental therapy, von Minckwitz said. Further, nonresponders experienced longer DFS (HR=0.6; 95% CI, 0.43-0.82), but not OS (HR=0.85; 95% CI, 0.57-1.27), when treated with response-guided chemotherapy vs. six cycles of TAC.

Results also indicated that responders who received eight cycles of TAC showed significantly longer DFS (HR=0.79; 95% CI, 0.62-0.97) and a trend toward longer OS (HR=0.76; 95% CI, 0.57-1.01) compared with those who received six cycles of TAC.

Subgroup analyses of treatment effects revealed no significant differences for age groups, stage, histologic type and grade. However, there was a significant interaction for hormone receptor status, according to von Minckwitz, with patients with hormone receptor-negative tumors experiencing no benefit from response-guided treatment.

When analyzed by phenotype, the researchers observed treatment effect among patients with luminal tumors who received response-guided treatment. However, response-guided treatment did not improve outcome in HER-2–positive and triple-negative tumors.

The researchers also examined the prognostic effect of pathologic complete response among the study population. In general, patients with a pathologic complete response had better DFS if they had triple-negative (P,.0001), non-luminal HER-2–positive (P,.0001) or luminal B HER-2–negative (P=.004) tumors. However, this was not true for patients with luminal A or luminal B HER-2–positive disease, von Minckwitz said.

Disclosure: Dr. von Minckwitz reports no relevant financial disclosures.

Earn CME this spring at the HemOnc Today Breast Cancer Review & Perspective meeting to be held March 23-24, 2012 at the Hilton San Diego Bayfront. See details at HemOncTodayBreastCancer.com.

For more information:

von Minckwitz G. S3-2. Presented at: the 2011 CTRC-AACR San Antonio Breast Cancer Symposium; Dec. 6-10, 2011; San Antonio.

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