A Review of the Relationship Between Obesity and Immunotherapy Response in Cancer

Obesity is a growing public health concern, being correlated with several comorbidities including heart disease, liver disease, diabetes, and several cancers. It has been demonstrated that obesity increases the risk of developing several types of cancers as well as being associated with a worse prognosis, increased metastasis, increased recurrence, and worse response to therapy. Paradoxically, early clinical trials of immune checkpoint inhibitors found a correlation between obesity and increased response to immune checkpoint inhibitors-a phenomenon referred to as the obesity paradox. Since then, numerous studies have been done to further examine the correlation between obesity and response to immune checkpoint inhibitors, with both confirmatory and non-confirmatory results depending on the type of cancer. Many of these studies have found contradicting results, indicating a need for further studies and meta-analyses to validate or refute this correlation. Here, we review recent studies on the correlation between obesity and response to immune checkpoint inhibitors across different types of cancer, with an emphasis on meta-analyses when available, discuss hypothesized mechanisms for this correlation, and highlight the knowledge gaps that need to be filled.