“TNBC is sensitive to chemotherapy, but a significant proportion of patients will eventually relapse after conventional anthracycline and taxane combinations, so we need new approaches to this population,” Dr. Martín noted.
The, joint GEICAM/2003-11 and CIBOMA/2004-01, was designed in 2004. Although no information about capecitabine in breast cancer was available at the time, the investigators selected this drug because it is non–cross-resistant with anthracyclines and taxanes.
About 55% of the patients randomized had node-negative disease and roughly 80% received adjuvant chemotherapy alone because neoadjuvant chemotherapy was generally not used 14 years ago, Dr. Martín noted.
After a median follow-up of 7.34 years, the 5-year disease-free survival rate—the trial’s primary endpoint—was 79.6% with capecitabine and 76.8% with observation, a nonsignificant difference in both unadjusted analysis (hazard ratio, 0.82; P = .136) and adjusted analysis (HR, 0.79; P = .082). The 5-year overall survival rate was 86.2% with capecitabine and 85.9% with observation, another nonsignificant difference (HR, 0.92; P = .623).
However, in subgroup analyses among the 248 patients with nonbasal disease, defined as immunohistochemically negative for both EGFR and CK5/6, capecitabine conferred a significant disease-free survival advantage (HR, 0.53; P = .02) and overall survival advantage (HR, 0.420; P = .007) relative to observation.
Interaction of basal/nonbasal phenotype with treatment was marginal for disease-free survival (P = .0694) and significant for overall survival (P = .0052).
In the nonbasal subgroup, the disease-free survival benefit of capecitabine was mainly driven by a reduction in distant recurrences, particularly in the liver and the brain.
Adjuvant capecitabine had tolerability that was “exactly as expected,” according to Dr. Martín. The median dose intensity was 86.3%, and 75.2% of patients completed all of the planned eight cycles.
The trial was supported by Roche, which also provided capecitabine. Dr. Martín reported receiving speaker’s honoraria from Pfizer and Eli Lilly; honoraria for participation in advisory boards from AstraZeneca, Novartis, Roche-Genentech, Pfizer, GlaxoSmithKline, PharmaMar, Taiho Oncology, and Eli Lilly; and research grants from Novartis and Roche.
SOURCE: Martín M et al. SABCS 2018, .