Yervoy (ipilimumab) is an immune checkpoint inhibitor drug used to treat advanced melanoma. It works by blocking the activity of a protein called CTLA-4, which can prevent the immune system from attacking cancer cells. While Yervoy has shown promising results in clinical trials, its effectiveness can be impacted by several factors, including the patient's weight.

According to a study published in JAMA Oncology [2], patients with a lower body mass index (BMI) may have a reduced response to immune checkpoint inhibitors like Yervoy. The study found that patients with a BMI of less than 25 had a significantly lower objective response rate and progression-free survival compared to patients with a BMI of 25 or higher. The researchers suggest that this may be due to the fact that adipose tissue can produce cytokines that activate the immune system and enhance the response to immunotherapy.

However, it is important to note that BMI is not a perfect measure of body composition, and other factors such as muscle mass and nutritional status may also play a role in the effectiveness of Yervoy and other immunotherapies. Additionally, the long-term side effects of immune checkpoint inhibitors can vary widely between patients, and more research is needed to understand the factors that influence treatment outcomes [3].

In conclusion, while underweight may impact the effectiveness of Yervoy and other immune checkpoint inhibitors, it is just one of many factors that can affect treatment outcomes. Patients should work closely with their healthcare providers to monitor their response to treatment and address any concerns or side effects that may arise.

Sources:
[2] https://jamanetwork.com/journals/jamaoncology/fullarticle/2799188
[3] https://www.cancer.gov/news-events/cancer-currents-blog/2021/immune-checkpoint-inhibitors-melanoma-long-term-side-effects
[1] https://www.drugpatentwatch.com/p/biologics/tradename/YERVOY