Which of the following drugs is a monoclonal antibody?

Rituximab (Rituxan) is indeed a monoclonal antibody, and this classification is crucial in understanding its mechanism of action in oncology. Monoclonal antibodies are laboratory-made molecules engineered to mimic the immune system's ability to fight off harmful pathogens such as bacteria and viruses. In the case of Rituximab, it specifically targets the CD20 protein found on the surface of B-cells, which plays a pivotal role in certain types of blood cancers such as non-Hodgkin lymphoma and chronic lymphocytic leukemia.

The design of monoclonal antibodies allows for targeted therapy, which can lead to fewer side effects compared to traditional chemotherapy. By specifically identifying and binding to CD20, Rituximab helps to destroy cancerous B-cells and can enhance the immune response against the tumor.

In contrast, Goserelin (Zoladex) is a synthetic hormone that acts as a gonadotropin-releasing hormone (GnRH) agonist, primarily used in hormone-sensitive cancers like prostate and breast cancer. Fulvestrant (Faslodex) is a selective estrogen receptor downregulator used to treat hormone receptor-positive breast cancer. Anastrozole (Arimidex) is