Dual HER2 blockade with pertuzumab (Perjeta) and trastuzumab (Herceptin) on top of anthracycline-based neoadjuvant chemotherapy for early-stage breast cancer was associated with a low rate of clinically relevant cardiac events in the final follow-up of the BERENICE study.
After more than 5 years, 1.0%-1.5% of patients who had locally advanced, inflammatory, or early-stage breast cancer developed heart failure, and around 12%-13% showed any significant changes in left ventricular ejection fraction (LVEF).
Importantly, “there were no new safety concerns that arose during long-term follow-up,” study investigator Chau Dang, MD, said in presenting the findings at the European Society for Medical Oncology: Breast Cancer virtual meeting.
Dr. Dang, a medical oncologist at Memorial Sloan Kettering Cancer Centre in New York, reported that the most common cause of death was disease progression.
BERENICE was designed as a cardiac safety study and so not powered to look at long-term efficacy, which Dr. Dang was clear in reporting. Nevertheless event-free survival (EFS), invasive disease-free survival (IDFS), and overall survival (OS) rates at 5 years were all high, at least a respective 89.2%, 91%, and 93.8%, she said. “The medians have not been reached,” she observed.
“These data support the use of dual HER2 blockade with pertuzumab-trastuzumab–based regimens, including in combination with dose-dense, anthracycline-based chemotherapy, across the neoadjuvant and adjuvant treatment settings for the complete treatment of patients with HER2-positive early-stage breast cancer,” Dr. Dang said.
Evandro de Azambuja, MD, PhD, the invited discussant for the trial agreed that the regimens tested appeared “safe from a cardiac standpoint.” However, “you cannot forget that today we are using much less anthracyclines in our patient population.”
Patients in trials are also very different from those treated in clinical practice, often being younger and much fitter, he said. Therefore, it may be important to look at the baseline cardiac medications and comorbidities, Dr. de Azambuja, a medical oncologist at the Institut Jules Bordet in Brussels, Belgium, suggested.
That said, the BERENICE findings sit well with other trials that have been conducted, Dr. de Azambuja pointed out.
“If we look at other trials that have also tested dual HER2 blockade with anthracycline or nonanthracycline regimens, all of them reassure that dual blockade is not more cardiotoxic than single blockade,” he said. This includes trials such as TRYPHAENA, APHINITY, KRISTINE, NeoSphere and PEONY.
The 3-year IDFS rate of 91% in BERENICE also compares well to that seen in APHINITY (94%), Dr. de Azambuja said.
BERENICE study design
BERENICE was a multicenter, open-label, nonrandomized and noncomparative phase 2 trial that recruited 400 patients across 75 centers in 12 countries.
Eligibility criteria were that participants had to have been centrally confirmed HER2-positive locally advanced, inflammatory or early breast cancer, with the latter defined as tumors bigger than 2 cm or greater than 5 mm in size, and be node-positive. Patients also had to have a starting LVEF of 55% or higher.
Patients were allocated to one of two neoadjuvant chemotherapy regimens depending on the choice of their physician. One group received a regimen of dose-dense doxorubicin and cyclophosphamide (ddAC) given every 2 weeks for four cycles and then paclitaxel every week for 12 cycles. The other group received 5-fluorouracil, epirubicin, and cyclophosphamide (FEC) every 3 weeks for four cycles and then docetaxel every 3 weeks for four cycles.
Pertuzumab and trastuzumab were started at the same time as the taxanes in both groups and given every 3 weeks for four cycles. Patients then underwent surgery and continued pertuzumab/trastuzumab treatment alone for a further 13 cycles.
The co-primary endpoints were the incidence of New York Heart Association class III or IV heart failure and incidence of symptomatic and asymptomatic LVEF decline of 10% or more.
The primary analysis of the trial was published in 2018 and, at that time, it was reported that three patients in the ddAC cohort and none in the FEC cohort experienced heart failure. LVEF decline was observed in a respective 6.5% and 2% of patients.