Some patients with HER2-positive breast cancer can reduce the intensity of adjuvant chemotherapy while maintaining the full benefits in terms of prognosis, new data suggest. Lowering the intensity of chemotherapy also reduces the adverse events that are associated with it.
An open-label study of about 400 participants indicated that 12 weeks of treatment with paclitaxel (Abraxane) and trastuzumab (Herceptin), followed by 9 months of trastuzumab monotherapy, was associated with very good long-term outcomes for patients with certain HER2-positive breast cancers. Few distant recurrences were observed, and tolerability was good.
The study was conducted by a team that included researchers from the European Institute of Oncology in Milan, one of the main oncology institutes in Italy.
“HER2-positive breast cancers harbor a particularly poor prognosis, compared with HER2-negative tumors, if left untreated. However, the blockade of HER2 with trastuzumab, when added to adjuvant multiagent chemotherapy, has been shown to improve outcomes for this population,” write the researchers, led by Sara M. Tolaney, MD, chief of breast oncology at Dana-Farber Cancer Institute in Boston. “To our knowledge, this is the first study to report the long-term outcomes of patients with small, node-negative, HER2-positive breast cancers prospectively treated with a de-escalated adjuvant regimen.”
The study was published in the March issue of Lancet Oncology.
Avoiding Side Effects
HER2-positive breast cancers, which are characterized by amplification of the HER2 gene and overexpression of the HER2 protein, account for 15% of new cases of localized breast cancer. They are more aggressive and resistant to some anticancer treatments but show sensitivity to stronger chemotherapy.
“We presented the 10-year analysis, which shows that survival for breast cancer among the 406 patients recruited in the study was 98.8% after 10 years, with only 6 recurrences,” study author Paolo Tarantino, MD, researcher at the European Institute of Oncology and clinical research fellow at Dana-Farber, said in a statement. “Our data support the use of the de-escalated adjuvant paclitaxel trastuzumab regimen as an adequate standard for small HER2-positive breast cancers, which avoids the side effects of polychemotherapy.”
The researchers also focused on patient selection and identified a significant relationship between the value of HER2DX, a new diagnostic tool capable of describing multiple characteristics of HER2-positive breast cancer, and the prognosis. If future research validates these preliminary results, the biomarker may help to further customize cancer treatments in the future, according to Tarantino.
“A Valuable Alternative”
“This is the 10-year update of the APT study, which is not randomized and has no control arm,” Alessandra Gennari, MD, PhD, associate professor of oncology at the University of Eastern Piedmont and head of oncology at Maggiore University Hospital in Novara, Italy, told Medscape Medical News. Gennari, who was not involved in the study, was lead author of the European Society for Medical Oncology’s 2021 guidelines on metastatic breast cancer. “This study shows, nevertheless, that in a subpopulation of HER2-positive patients with low to moderate risk of recurrence, the de-escalation of chemotherapy together with trastuzumab is a valuable alternative to more complex regimens with chemotherapy agents and is very well tolerated.”
Gennari’s comment echoes those of an editorial that accompanied the Lancet Oncology study. “This work represents a milestone in the history of breast cancer: we have definitively shown that for early HER2-positive tumors, you can do less by getting more,” co-author Giuseppe Curigliano, MD, PhD, full professor of medical oncology at University of Milan and head of early drug development at the European Institute of Oncology, told Medscape. “It completes a pathway started by my group at the European Institute of Oncology in 2009, when we showed that HER2-positive tumors have a very good prognosis if diagnosed at a very early stage, and therefore can be treated with less aggressive and less toxic chemotherapies.” Candiolo Cancer Institute oncologists Elena Geuna, MD, and Filippo Montemurro, MD, co-authored the editorial with Curigliano.
Research on de-escalation increased after that study, and data showed that a lighter chemotherapy regimen is safe and effective and allows patients to live longer and with fewer side effects. “This finding immediately changed clinical practice, and the newly published work now adds an important piece: de-escalation maintains its benefit over the long term, beyond 10 years,” said Curigliano. “It also shows that in the future, we could identify the patients that will benefit from doing more, but also those that will benefit from doing even less, thanks to the new marker HER2DX.”
The study was funded by Genentech. Tolaney has received consulting or advisory board fees from Genentech, AstraZeneca, Eli Lilly, Merck, Novartis, Pfizer, Gilead, BMS, Eisai, Sanofi, and other pharmaceutical companies. Tarantino has received consulting or advisory board fees from AstraZeneca, Daiichi-Sankyo, and Lilly and has received payment or honoraria for educational events from AstraZeneca and Daiichi-Sankyo. Curigliano and Gennari reported no relevant financial relationships.
Lancet Oncol. Published March 2023 issue. Abstract, Editorial
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