Manoj Kumar is currently a postdoctoral fellow at the Daldrup-Link laboratory in the Department of Radiology at Stanford University. He is working on designing PET and MRI imaging probes to enable real-time visualization of immune markers in the tumor microenvironment and develop more effective immunotherapy approaches for imaging-guided cancer treatment. Manoj received his Ph.D. in Clinical Investigation from the University of Wisconsin-Madison in 2020. His doctoral research focused on PET imaging of steroid hormone receptors to evaluate endocrine therapy response in advanced breast cancer. He has authored publications on molecular imaging, hormone receptor biology, cancer biology, and drug delivery.
Cancer immunotherapies aim to overcome the immune-suppressive barriers in the tumor microenvironment through activation or modulation of the innate or adaptive immune signals. Non-invasive imaging approaches such as positron emission tomography (PET) and magnetic resonance imaging (MRI) enable visualizing the tumor microenvironment's immune compositions and dynamic changes in response to immunotherapy. Integrated PET/MRI enables simultaneous in vivo tracking of more than one immune target in the tumor, informing the development of more efficient immunotherapies.
B7-H4 is a recently discovered immune checkpoint protein that inhibits anti-tumoral T-cell function. We present a new imaging approach using a newly developed PET probe for imaging B7-H4 in mouse models of prostate cancer and osteosarcomas. Since B7-H4 inhibits the interaction between T-cells and tumor-associated macrophages (TAMs), we combined our imaging approach with ferumoxytol-enhanced MRI to track tumor-associated macrophages (TAMs) simultaneously. We demonstrate how B7-H4 expression on prostate cancers and osteosarcomas can be quantified with PET imaging. In addition, we show how integrated PET/MRI can demonstrate TAM activation after the B7-H4 blockade. We then investigate the ability of our integrated PET/MRI approach to predict tumor response to different combination immunotherapies by quantifying B7-H4 expression and TAM responses in the tumor microenvironment.