Abstract
What is this summary about?
This article summarizes the most recent results of the monarchE study. This study was completed in participants with a type of breast cancer called HR+, HER2-, node-positive, high-risk early breast cancer. In this study, abemaciclib, a non-chemotherapy treatment, was administered with standard of care endocrine therapy after curative surgery. Most participants had received prior chemotherapy and/or radiotherapy. The study investigated if abemaciclib helped participants live longer without their cancer returning compared with participants who only received standard of care endocrine therapy. The study participants were assigned to 1 of 2 treatment groups. Participants in Group A were assigned to receive standard of care endocrine therapy with abemaciclib for 2 years, followed by endocrine therapy for a total of at least 5 years. Participants in Group B were assigned to receive standard of care endocrine therapy only for at least 5 years. The effect of treatment was compared between these 2 groups.
What were the results?
Overall, the results showed that the cancer was 34% less likely to come back after surgery in the participants in Group A (abemaciclib plus endocrine therapy) compared with those in Group B (endocrine therapy only). At 4 years since the start of the study treatment, more participants who received the combination of abemaciclib plus endocrine therapy remained free of cancer compared with participants who received endocrine therapy alone (86% versus 79%). Participants who received abemaciclib plus endocrine therapy had more side effects than those who received endocrine therapy alone, but most of these effects were mild to moderate and reversible upon the end of therapy. The most common side effects in the abemaciclib group were diarrhea, infections, low number of white blood cells, and tiredness.
What do the results mean?
This study found that administering abemaciclib in combination with standard endocrine therapy after curative breast surgery helped lower the risk of cancer returning in people with HR+, HER2-, node-positive, high-risk early breast cancer. Abemaciclib is a new treatment option for people with this diagnosis. People with high-risk early breast cancer should always talk to their doctors and nurses before making any decisions about their treatment.
Clinical Trial Registration: NCT03155997 (monarchE study)
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Financial disclosure
The monarchE study was sponsored by Eli Lilly and Company. Eli Lilly and Company funded the medical writing support and journal publishing costs of this plain language summary of publication. Dr Johnston reports honoraria for Pfizer, Novartis, Eisai, AstraZeneca, Roche, Eli Lilly; consulting or advisory role for Eli Lilly, Puma Biotechnology, Novartis, Pfizer; research funding for Pfizer, Puma Biotechnology. Dr Rugo reports consulting or advisory role for Napo Pharmaceuticals, Scorpion Therapeutics, Blueprint Medicines, Puma Biotechnology; research funding for OBI Pharma, Pfizer, Novartis, Lilly, Genentech, Merck, Daiichi Sankyo, Sermonix Pharmaceuticals, AstraZeneca, Gilead Sciences, Astellas Pharma, Pionyr, Taiho Oncology, GlaxoSmithKline; travel, accommodations, expenses for Merck, AstraZeneca, Gilead Sciences. Dr Tolaney reports research funding for AstraZeneca, Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics/Gilead, Exelixis, Bristol-Myers Squibb, Eisai, Nanostring, Cyclacel, Odonate, and Seattle Genetics; consulting or advisory role for AstraZeneca, Eli Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics/Gilead, Bristol-Myers Squibb, Eisai, Nanostring, Puma, Sanofi, Silverback Therapeutics, G1 Therapeutics, Athenex, OncoPep, Kyowa Kirin Pharmaceuticals, Daiichi-Sankyo, Ellipsis, Infinity, 4D Pharma, and Samsung Bioepsis Inc., Chugai Pharmaceuticals, BeyondSpring Pharmaceuticals, OncXerna, OncoSec Medical Incorporated, Certara, Mersana Therapeutics, CytomX, Seattle Genetics. Dr Munoz Fernandez reports employment and stock/ownership interests for Eli Lilly. Dr Wei reports employment and stock/ownership interests for Eli Lilly. Dr Martin reports honoraria for Roche/Genentech, Lilly, Pfizer, Novartis, Pierre Fabre, Seagen; consulting or advisory role for Roche/Genentech, Novartis, Pfizer, Lilly, AstraZeneca, Daiichi Sankyo; speakers' bureau for Lilly/ImClone, Roche/Genentech, Pierre Fabre 19; research funding for Novartis, Roche, Puma Biotechnology; Travel, Accommodations, Expenses for Daichii-Sankyo; other relationships for Roche, Novartis. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
Writing disclosure
Maeve O'Connell, PhD, of Eli Lilly and Company, provided medical writing support and Praveen Shetty of Eli Lilly Services India Private Limited, provided graphical design support for this plain language summary of publication.
Acknowledgments
We thank the 5637 participants and their families/caregivers from 603 sites in 38 countries for participating in this study. We are grateful for the investigators and their support staff who generously participated in this work.
Competing interests disclosure
The authors have no competing interests or relevant affiliations with any organization or entity with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, stock ownership or options and expert testimony.