The FDA has approved pertuzumab (Perjeta) in combination with trastuzumab (Herceptin) and chemotherapy as an adjuvant treatment for patients with HER2-positive early breast cancer at high risk for recurrence, based on findings from the APHINITY trial.
The phase III double-blind, placebo-controlled APHINITY trial randomized patients with operable HER2+ early (T1-3) breast cancer in a 1:1 ratio to adjuvant treatment with trastuzumab plus chemotherapy (anthracycline or non-anthracycline-containing regimen) with pertuzumab (n = 2400) or placebo (n = 2404). Patients had undergone mastectomy or lumpectomy. Overall, 63% of the participants had node-positive disease and 36% had HR-negative disease.
The pertuzumab arm received 6 to 8 cycles of chemotherapy with pertuzumab and trastuzumab, followed by pertuzumab and trastuzumab alone every 3 weeks for a total of 1 year of therapy. The control arm received the same treatment schedule, with placebo replacing pertuzumab. At the end of adjuvant chemotherapy, patients could start receiving radiotherapy and/or endocrine therapy. The primary endpoint was iDFS, with secondary endpoints including cardiac and overall safety, overall survival, disease-free survival, and health-related quality of life.
Although still early, there had been fewer deaths in the pertuzumab arm (n = 80) versus the placebo group (n = 89). There was a nonstatistically significant trend toward improvement in overall survival with pertuzumab (HR, 0.89; 95% CI, 0.66-1.21; P
The iDFS benefits were more pronounced among higher-risk subgroups. At 3 years, the iDFS rate for patients with node-positive disease was 92.0% with pertuzumab versus 90.2% with standard therapy (HR, 0.77; 95% CI, 0.62-0.96; P
= .019). At 4 years, the rates were 89.9% and 86.7%, respectively. Those with node-negative disease, had 3-year iDFS rates of 97.5% and 98.4% in the pertuzumab and placebo groups, respectively (HR, 1.13; 95% CI, 0.68-1.86).
For participants with hormone receptor (HR)–negative disease, the 3-year iDFS rate with pertuzumab was 92.8% compared with 91.2% in the control group (HR, 0.76; 95% CI, 0.56-1.04; P
= .085). At 4 years, the rates were 91.0% and 88.7%, respectively. In the HR-positive subgroup, the iDFS rate was 94.8% with pertuzumab and 94.4% with placebo (HR, 0.86; 95% CI, 0.66-1.13).
The addition of pertuzumab did not significantly increase cardiotoxicity. The primary cardiac endpoint was heart failure, defined as New York Heart Association class III/IV failure plus a drop in left ventricular ejection fraction (≥10% from baseline and to <50%), or cardiac death. Primary cardiac events were reported in 17 patients (0.7%) in the pertuzumab-containing arm versus 8 participants in the standard therapy group (0.3%). The primary cardiac endpoint also included cardiac death, and the 17 and 8 primary events includes the two cardiac deaths in each arm.
The most common grade 3/4 adverse events (AEs) in the pertuzumab and placebo groups, respectively, were neutropenia (16% vs 16%), febrile neutropenia (12% vs 11%), diarrhea (10% vs 4%), and anemia (7% vs 5%). Fatal AEs occurred in 0.8% of patients in each group. AEs led to dose discontinuations for 7.3% of patients in the pertuzumab group versus 6.4% with placebo.
Pertuzumab was initially approved by the FDA in June 2012 in combination with trastuzumab and docetaxel for the treatment of patients with HER2-positive metastatic breast cancer who had not received prior anti-HER2 therapy or chemotherapy for metastatic disease. Regulatory decisions are still anticipated in the European Union, with a meeting of the National Institute for Health and Care Excellence scheduled for May 22, 2018.
von Minckwitz G, Procter MJ, De Azambuja E, et al. Adjuvant Pertuzumab and Trastuzumab in Early HER2-Positive Breast Cancer. N Engl J Med. 2017; 377:122-131.