 As with all treatments, Prolucan may cause certain side effects that can range from mild to severe and sometimes fatal. During the course of the recommended two cycles of five-day treatments, patients are hospitalized in a treatment center that specializes in administering and managing Prolucan therapy. Prolucan side effects are usually manageable and typically occur while the patient is still in a Prolucan high-dose treatment center where a specialized team is assigned to your care. Although side effects can be severe, they usually disappear within two to three days of stopping treatment when properly managed. Doctors typically know whether or not patients have responded to Prolucan therapy within six to twelve weeks of initiating therapy. NCCN Clinic Practice Guidelines and Oncology recommend high-dose IL-2 immunotherapy as an option for first-line therapy in selected cases for metastatic predominant clear-cell kidney cancer. Once a patient initiates another type of therapy and their overall health has declined, they may no longer be eligible for IL-2. IL-2 is also recommended as an option to use first by the Society for immunotherapy for cancer in the treatment of patients with metastatic melanoma. This is why it is important to talk to your doctor about whether you may be an appropriate candidate for immunotherapy and if it should be considered as part of your treatment plan.