Pilot Study of Bone Mineral Density Changes During Anti-PD-1 Immunotherapy

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment and work by blocking protein interactions that normally prevent the immune system from recognizing and destroying cancer cells. However, these agents, now approved for over 15 types of cancers and for both early-stage and metastatic disease, are capable of causing inflammation in any organ system of the body that can lead to organ damage, dysfunction, and even death in rare cases. Some patients may suffer acute and treatable complications like joint pain, but some may have irreversible complications like hypothyroidism that requires daily, life-long medication. It is therefore important to fully understand the different types of damage ICIs can cause to better monitor patients receiving ICI therapy. A rising concern from recent reports in the literature is that ICIs may weaken bone and increase the risk of fractures. In this study, we aim to characterize how ICIs impact the bone by examining several factors in patients undergoing curative-intent ICI treatment either alone or in combination with chemotherapy: bone mineral density, bone volume, and markers of bone turnover in the blood. We will use two imaging techniques to assess bone mineral density and volume. DXA (dual X-ray absorptiometry) imaging uses low-dose X-rays to measure how dense (or strong) bones are and is often used to diagnose or assess the risk of osteoporosis. High-resolution peripheral quantitative computed tomography (HRpQCT) is a 3D imaging technology that can quantify bone structure and volume and offers high resolution that can be used to assess bone in smaller bones of the peripheral skeleton. We hypothesize that ICI treatment will weaken bones and increase the risk of fractures. As ICI therapy is relatively new, a rising number of patients may be at risk of fractures or have low bone density that is not being monitored because there are not guidelines in place notifying physicians of this potential risk to patients. Our study will provide important preliminary data that will be the basis for larger studies in the future aiming to better monitor and potentially treat bone weakening in patients treated with ICIs to reduce the pain, inconvenience, and complications from fragility fractures.