The Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimization (NeoALTTO BIG-06) trial, which assessed lapatinib (Tykerb) and trastuzumab (Herceptin) given prior to surgery in patients with early human epidermal growth factor receptor 2 (HER2)–positive breast cancer disclosed that women who had no signs of residual disease after treatment, also known as a pathological complete response (pCR), survived longer without the cancer returning than those who did not.

In addition, the study discovered that this was more lkely to occur in patients who received the two anticancer drugs together, rather than as single agents. Results from nearly 10 years of follow-up from the international trial, in which patients were randomized to receive either trastuzumab or lapatinib alone or in combination, was recently presented at the 12th European Breast Cancer Conference.

The NeoALTTO BIG-06 trial enrolled 455 women with early HER2-positive cancer. Following surgery, the study participants were given three cycles of chemotherapy followed by 34 weeks of whichever therapy they had originally been randomized to receive. With an average follow-up of 9.7 years, event-free survival (EFS) was observed in 69% of the patients receiving both drugs, 65% of the trastuzumab-only group, and 63% of the lapatinib-only group. However, these variations were not deemed to be statistically meaningful.

Overall survival (OS) rates were 80% in the combination group, 77% in the lapatinib group, and 76% in the trastuzumab group, with no statistically significant differences between the groups. When women who had attained pCR were compared with those who had not across all three treatment groups, researchers found that EFS and OS were significantly better in women who had pCR, with 77% of patients who achieved pCR surviving 9 years event-free compared with 61% of patients who did not achieve a pCR. Further, 88% of patients who achieved pCR were still alive at 9 years compared with 72% of patients who did not.

Subgroup analysis demonstrated that these associations were statistically significant in women who received the drug combination and in those who were hormone receptor (HR)–negative. This trial has the longest follow-up of randomized clinical trials looking at HER2 breast cancer and demonstrates how critical it is to follow patients for as long as possible to fully understand how drug combinations and other factors can affect survival.

Chief researcher Paolo Nuciforo, MD, of the Vall d’Hebron Institute of Oncology in Barcelona, Spain, stated, “Although overall survival rates did not differ significantly between the three treatment groups, nearly twice as many patients achieved pCR if they received both drugs, 51% compared to 27.1% of patients receiving only one drug in the other two arms of the study combined. The results from this analysis show that patients who achieve pCR are significantly more likely to survive for longer than those who do not achieve pCR. This validates pCR as an early indicator of long-term outcome for HER2-positive disease and could help doctors decide on the best treatment.”

Dr. Nuciforo also noted, “On one hand, patients not achieving a pCR may be at higher risk of recurrence and giving extended therapy to them could potentially lower this risk. On the other hand, those patients who do achieve pCR could be spared additional toxic treatments.”

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.
« Click here to return to Oncology Update.