Does a 2-week course of atezolizumab (drug) as monotherapy prior to the standard combination therapy of chemotherapy and atezolizumab provide any additional benefit in triple-negative breast cancer?

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’s 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 expression of the HER2 protein on the cells (HER2-positive). If neither hormone receptors nor the HER2 receptor are present, the cancer is referred to as triple-negative breast cancer (TNBC).

Fewer treatment options are available for this variant, since hormone and HER receptors are typical targets of medications used for treatment. Treatment for breast cancer at a locally confined stage with no evidence of distant metastases typically involves breast-conserving surgery preceded by chemotherapy (neoadjuvant) with the goal of complete recovery. In the case of triple-negative breast cancer, this is usually done with chemotherapy in combination with a checkpoint inhibitor (known as PD-L1); one drug in this class is atezolizumab, which is already approved for the treatment of triple-negative breast cancer. This drug enables the body’s immune system to recognize and fight the cancer.

The goal of the NeoMono study is to investigate whether the effectiveness of neoadjuvant combination therapy consisting of chemotherapy and atezolizumab can be improved by administering atezolizumab alone for 2 weeks prior to the start of treatment. This will be compared with the current standard of care, which involves starting combination therapy immediately. The study thus has two groups (arms): In one arm, patients first receive two weeks of atezolizumab monotherapy, followed by a combination of atezolizumab and standard neoadjuvant chemotherapy. In the other arm, patients receive combination therapy with atezolizumab and standard neoadjuvant chemotherapy from the start. The study is randomized and open-label; this means that patients and treating physicians are randomly assigned to a group but know which group they are in. If medications for the disease have already been administered, it may be necessary to allow a certain interval between the end of that therapy and the start of the study treatment. The study initially lasts 26 weeks, after which researchers will assess whether any residual tumor remains in the breast or lymph nodes. This is followed by a follow-up period.

Women and men over the age of 18 with unilateral triple-negative breast cancer are eligible to participate in the study. Participation in this study requires that there be no metastases (Stage 4) and that the patient’s overall health allows for treatment with the prescribed medications. Women of childbearing age must use effective contraception for a specified period during and after treatment. Patients with a history of cancer, certain autoimmune diseases, or severe cardiovascular diseases are excluded from participation. It does not matter whether PD-L1 is detected on the cancer cells or not.