Which function do monoclonal antibodies primarily serve in biotherapy?

Monoclonal antibodies primarily serve to enhance the immune response against cancer by specifically targeting cancer cells. These engineered antibodies are designed to recognize and bind to particular antigens present on the surface of cancer cells. By binding to these antigens, monoclonal antibodies can recruit various components of the immune system to attack and destroy the cancer cells more effectively. This targeted approach allows for a more precise attack on cancerous tissues while sparing normal cells, thereby reducing the likelihood of collateral damage.

In contrast to enhancing immune responses, the other options describe roles that are less central to the function of monoclonal antibodies. While alleviating chemotherapy side effects and improving drug absorption are important aspects of cancer treatment, they are not primary functions of monoclonal antibodies. Additionally, while monoclonal antibodies may contribute to tumor shrinkage, their main therapeutic purpose is to mobilize the immune system against cancer rather than serve as a preoperative reduction strategy.