SAN ANTONIO – Adjuvant capecitabine does not improve outcomes in women with early-stage triple-negative breast cancer (TNBC) who have undergone resection and received standard chemotherapy, finds a phase 3, randomized, controlled trial jointly conducted by the Spanish GEICAM group and the Central and South American CIBOMA group. But the story may not end there.
Findings reported in a session and press conference at the San Antonio Breast Cancer Symposium showed that, compared with observation, eight cycles of adjuvant capecitabine (Xeloda) reduced the 5-year risks of disease-free survival events and death by a nonsignificant relative 18% and 8%, respectively, among all 876 women randomized. However, the subgroup whose tumors had the nonbasal phenotype saw large significant benefits, with 47% and 58% relative reductions in these risks, respectively.
“The trial is formally negative,” commented lead investigator, head of the medical oncology service at Hospital Gregorio Marañón in Madrid. However, the observation arm fared better than expected. In addition, the trial had a very low–risk patient population, which may help explain why its findings differ somewhat from the more positive findings of the similar trial.
“Our data don’t speak against the CREATE-X study. My personal view is that capecitabine is useful for some TNBC patients,” Dr. Martin said. “Our study is not finished because we are going to look at the genomic characteristics of this group defined as non–basal-like because we want to know more about this subgroup. We are planning also to reproduce our subset in the CREATE-X trial to see if this is a real finding because we are in the era of personalized medicine.”
TNBC is a broad group defined only by negative findings for the main markers having available treatments, he elaborated. “So if we could define a subpopulation that actually benefited from capecitabine, this will be great for the patients.” Currently, conventional pathology does not routinely report on tumor basal phenotype, so all TNBC patients receive the same drugs. “This is a mistake. We should select the right drug for the right patient. Probably not all breast cancer patients are sensitive to the same drugs. But the fact is that we don’t have funding to run trials looking at that because this kind of trial is not interesting for pharma companies.”
“That’s an important message that triple-negative is really a big, very heterogeneous group,” agreed SABCS codirector and press conference moderator, director of the Harold C. Simmons Comprehensive Cancer Center and associate dean of oncology programs at the University of Texas, Dallas.
Patients and clinicians alike are largely unaware of the presence of TNBC basal and nonbasal subtypes and their potential importance, he said. “We all need some education on that, us included. It’s a very, very heterogeneous group, it is one that is very challenging. We need to start by educating all of us that there is a need to do research on that. ... We have a duty to define this phenotype better.”