Chicago (USA), Jun 2 (EFE).- Combining hormone therapy with the drug ribociclib significantly reduces the risk of relapse in early-stage HR+/HER2- breast cancer, the most common subtype.
The reduced risk was shown in the NATALEE phase III clinical trial, headed by the American oncologist Dennis Slamon.
The study was published on Friday, coinciding with the inauguration in Chicago of the American Society of Clinical Oncology (ASCO) congress, the sector’s leading event, which has brought together some 40,000 participants until Tuesday.
The study, funded by drugmaker Novartis, was conducted from January 2019 to April 2021 among 5,101 men and pre- and postmenopausal and women from 20 countries with early stage IIA, IIB, or III HR+/HER2- breast cancer and risk of recurrence.
Participants were randomized to be treated with ribociclib for three years, along with five years of hormone therapy, or with hormone therapy alone for at least five years. There were 2,549 people in the first group and 2,552 in the second.
Ribociclib is an inhibitor of CDK4/6 proteins, which regulate the cell cycle.
At follow-up in January of this year, 74.7% of the participants had remained in the study: 1,984 with ribociclib plus hormone therapy and 1,826 with hormone therapy alone.
The study found that adding ribociclib to hormone therapy improved survival free of signs or symptoms and that the risk of recurrence decreased by 25 %.
Of the 426 cancer-free survival cases studied, there were 189 relapses in the ribociclib group (7.4 % of patients) and 237 in the hormone therapy alone group (9.2 %).
The 3-year cancer-free survival rate was 90.4 % in the ribociclib-treated group and 87.1 % in the hormone therapy alone group.
The benefits observed were consistent regardless of the stage of disease in the patients and whether or not they were menopausal.
The currently recommended starting dose of ribociclib is 600 milligrams. However, according to the study, a prolonged duration can help prevent cells from doubling and dividing, and destroy the remaining cancer cells.
Therefore, to reduce side effects and maintain efficacy, the study authors chose a 3-year treatment with ribociclib at a dose of 400 milligrams per day for three weeks, followed by a week off.
Among the most common side effects detected with the use of ribociclib are joint pain and a decrease in the number of white blood cells (neutropenia).
Slamon, the study’s author, recalls that most breast cancers are diagnosed at an early stage (I to III). Currently, the usual treatment for patients with HR+/HER2- is surgery with or without chemotherapy or radiation, followed by 5 to 10 years of hormone therapy.
The next step now is to further evaluate how the addition of ribociclib plus hormone therapy influences quality of life, and to continue to follow patients to analyze long-term results. EFE