A new study has reported that treatment with Herceptin (trastuzumab) for one year after chemotherapy improves survival in patients with human epidermal growth factor receptor 2 positive (HER2+) breast cancer. The study included 3,401 participants in the Herceptin Adjuvant (HERA) trial, which is an international phase 3 trial comparing treatment with Herceptin for one and two years with observation after standard neoadjuvant chemotherapy (chemotherapy before breast cancer surgery), adjuvant chemotherapy (after surgery), or both in patients with HER2-positive early breast cancer.
The primary endpoint was disease-free survival; overall survival was also measured. The median follow-up period was approximately four years. After treatment with Herceptin was found to have a benefit the first time the results were calculated (at about the one-year mark), patients in the non-Herceptin group (the observation group) were permitted to receive Herceptin. In the present study, the authors report trial outcomes for the one-year Herceptin (1,703 participants) and observation (1,698) groups at a median follow-up of 48.4 months and examine the impact of the extensive crossover to Herceptin that occurred.
A significant disease-free survival benefit was found in favor of patients in the Herceptin group (four-year disease-free survival = 78.6%) compared to the observation group who did not receive Herceptin (four-year disease-free survival = 72.2%). Analysis of overall survival found no statistically significant difference in the risk of death (overall survival = 89.3% for the Herceptin group compared to 87.7% for the observation group) as of four years. A total of 885 (52%) patients in the observation group elected to cross over to receive Herceptin, beginning Herceptin treatment at a median of 22.8 months from joining the study. Participantswho did so had 32% fewer breast cancer recurrences than those remaining in the observation group. Higher rates of grade 3, grade 4, and fatal adverse events were found in the Herceptin group compared to the observation group. The most common grade 3 or 4 adverse side effects, each occurring in under 1% of patients, were congestive heart failure, hypertension, muscle and joint pain, infection, hot flush, headache, and diarrhea. The authors conclude that treatment with Herceptin for one year after chemotherapy is associated with significant clinical benefit at four-year follow-up. Among patients assigned to the observation group, crossing over to Herceptin was also associated with improved outcomes.