A Study on the Safety and Tolerability of SGN-PDL1V, a New Antibody-Chemotherapy Combination Drug, in Patients with Advanced Triple-Negative Breast Cancer

Breast cancer (mammary carcinoma) is a malignant disease of the mammary gland tissue characterized by the uncontrolled proliferation of mammary gland cells. Treatment of the disease depends on numerous factors, such as the patient’s overall health, the stage (extent) of the disease, the tumor’s growth rate (Ki-67 index), detectable hormone receptors on the surface of the cancer cells (estrogen receptor-positive, progesterone receptor-positive), and the increased presence of the HER2 protein on the cells (HER2-positive). In a locally advanced stage (Stage 3A, 3B) or when breast cancer has already spread to other parts of the body (metastases), the disease is often no longer curable. In such cases, the goal is to “keep the disease at bay” for as long as possible.

If the tumor cells do not have any hormone or HER2 receptors on their surface, the cancer is referred to as triple-negative breast cancer. Fewer treatment options are available in these cases, so new drugs are being sought, particularly for advanced and/or metastatic stages.

SGN-PDL1V is a new targeted drug consisting of two components—an immunotherapy (antibody) and chemotherapy—that specifically targets the PD-L1 protein on cancer cells. The antibody binds to PD-L1 and delivers a potent cytotoxic agent (MMAE) directly into the tumor cells, where it is released and blocks cell division, causing the cells to die. In addition, blocking PD-L1 can activate the immune system to better fight the tumor.

This study is investigating this new drug in terms of dosage, efficacy, and tolerability. In the first phase, all patients receive the experimental treatment, and its efficacy and safety are evaluated to determine the optimal dosage. In the subsequent phase, patients receive the determined dose over a longer period. Follow-up is planned to last approximately 3 years. All patients participating in this study will receive the experimental treatment; however, the treatment will differ depending on which phase the study is currently in. Assignment is therefore sequential rather than random. The duration of treatment depends on the success of the therapy and on side effects.

Women and men aged 18 and older with triple-negative, locally advanced, or metastatic cancer who have PD-L1 proteins on their cancer cells are eligible to participate in the study. In addition, for the initial phases of the study, patients must have already been treated with all lines of standard therapy and, in the opinion of their treating physicians, must no longer be eligible for any further lines of standard therapy. If patients have previously been treated with PD-L1 inhibitors, a certain period of time must elapse between that treatment and the start of the study therapy. Patients with active brain metastases are also excluded from participating in the study.