A novel drug for adjuvant anti-hormone therapy in early-stage breast cancer (0-2)

Breast cancer (mammary carcinoma) is a malignant disease of the breast gland tissue characterized by the uncontrolled proliferation of breast gland cells. Treatment of the disease depends on numerous factors, such as the patient’s overall health, the stage of the disease, the tumor growth rate (Ki-67 index), the presence of detectable hormone receptors on the surface of the cancer cells (estrogen receptor-positive, progesterone receptor-positive), and the increased presence of HER2 receptors on the cells (HER2-positive). Cancer cells often have hormone receptors, making anti-hormone therapy a core component of treatment.

Treatment is typically divided into two phases (neoadjuvant and adjuvant), unless metastases are already present. Neoadjuvant therapy constitutes the first phase. This is followed by breast surgery. Depending on the disease’s risk profile, adjuvant therapy usually follows; in the case of HR-positive breast cancer, this involves anti-hormone therapy. One class of drugs used in standard anti-hormone therapy is aromatase inhibitors, such as anastrozole, letrozole, and exemestane; another group consists of “selective estrogen receptor modulators” (SERMs), which include tamoxifen. Earlier studies have shown that combining anti-hormonal therapy with another active ingredient—a CDK4/6 inhibitor such as abemaciclib—can increase the treatment’s effectiveness.

The CAMBRIA-2 study is investigating camizestrant, a new drug in the SERM class, to assess its efficacy and safety compared to standard anti-hormonal therapy. Camizestrant can also be administered with or without abemaciclib. Patients are randomly assigned to one of the two study groups and receive either standard therapy (control arm), in which the anti-hormone therapy drug is selected by the treating physician, or, in the other group (study arm), the new drug camizestrant. Both groups may be treated with or without the CDK 4/6 inhibitor abemaciclib.

The duration of treatment is planned for 7 years in both study arms. The total follow-up period will last up to 14 years. The medication has already been studied in smaller Phase 2 trials, where it demonstrated advantages over standard therapy. Patients know which study arm they are in.

Women and men aged 18 and older with hormone receptor-positive, HER2-negative early-stage breast cancer (stages 0–2) are eligible to participate in the study. The breast cancer must have already been treated surgically—meaning the first phase of treatment (usually chemotherapy plus surgery) must be complete—but the surgical removal of the tumor must have taken place no more than 12 months ago. There must be a moderate or high risk of recurrence; neoadjuvant therapy is not required. Patients may have received anti-hormone therapy for a maximum of 12 weeks.