6-month trastuzumab noninferior to 12 in HER2+ BC, with less cardiotoxicity
Treatment with adjuvant trastuzumab for 6 months was noninferior to 12 months — the current standard treatment duration for HER2-positive early-stage breast cancer — in terms of disease-free survival (DFS), according to the PERSEPHONE* trial presented in ASCO 2018.
After a median follow-up of 5.4 years, similar proportion of patients survived and remained disease-free in both the 6-month and 12-month trastuzumab arms (4-year DFS rate, 89.4 percent vs 89.8 percent, hazard ratio [HR], 1.07; p-noninferiority=0.01), hence meeting the noninferiority criterion of HR <1.29. [ASCO 2018, abstract 506]
Furthermore, significantly fewer patients receiving 6-month therapy had to discontinue trastuzumab because of cardiotoxicity compared with those on 12-month therapy (4 percent vs 8 percent; p<0.0001). Patients on 6-month therapy also had a more rapid recovery of cardiac function post-trastuzumab than those in the 12-month group (p=0.02).
“This new trial shows that a shorter length of treatment can benefit patients just as much as a longer treatment, with less risk of cardiac side effects. This is a win-win for patients with breast cancer who are receiving this common treatment,” said ASCO President Bruce Johnson, Professor of Medicine at Harvard Medical School in Boston, Massachusetts, US.
Other adverse events that were significantly reduced with the 6-month therapy included cough (p=0.003), pain (p=0.003), fatigue (p=0.009), chills (p=0.02), and palpitations (p=0.03). Grade 3/4 adverse event rates were also lower in the 6-month vs the 12-month therapy groups (18 percent vs 23 percent; p=0.004).
“They were at a low level, certainly as compared to chemotherapy, but patients tell us [these toxicities] impact their lives. More importantly, patients undergoing 6 months of treatment can return more quickly to their normal lives,” said lead author Dr Helena Earl, Professor of Clinical Cancer Medicine at the University of Cambridge in Cambridge, UK.
The phase III multicentre noninferiority trial randomized 4,089 women (67 percent aged >50 years) with HER2-positive invasive early breast cancer in a 1:1 ratio to receive 6 or 12 months of adjuvant trastuzumab. During the study, the patients were also given chemotherapy which was either taxane-based, anthracycline-based, or a combination of both. After a median 5.4 years of follow-up, 8 percent of the patients died and 13 percent had relapsed or died.
“The exciting results mark the first steps to the reduction of treatment duration for many women with HER2-positive breast cancer,” said Earl.
“Quality of life, patient-reported experience, and health-economic assessments are ongoing,” she added.
In the future, the researchers planned to define in which group of patients can the treatment duration be safely reduced by analysing blood and tumour samples of the patients for biomarkers.
Earl also cautioned that more detailed analyses need to be conducted and specialists will need time to review the results before they can suggest any change in practice. “This is a real-world result…. But we need to be very careful and cautious about saying at this point that 6 months of trastuzumab is enough.”
“Declaring victory with only 8 percent of deaths and 12 percent of recurrences may be a bit early—too early to make a definite change in practice,” agreed Johnson, who nonetheless noted that the benefit of reduced cardiac toxicity is clear.