Geoffrey B. Johnson, MD, PhD

Geoffrey B. Johnson, MD, PhD

Mayo Clinic

Rochester, Minnesota

Dr. Geoffrey Johnson is a thoracic radiologist and nuclear medicine physician at the Mayo Clinic in Rochester, MN and is chair of the nuclear medicine division. He received his undergraduate degree in chemical engineering at MIT, his medical degree from the Mayo Clinic School of Medicine, and his Ph.D. in Immunology from Mayo Graduate School. He specializes in nuclear cardiology, nuclear medicine, thoracic imaging, and nuclear radiology and is experienced in nuclear therapy, amyloidosis, positron emission tomography (PET/CT and PET/MR), and lung neoplasms. He has a joint appointment in immunology. Dr. Johnson’s research interests include PET and SPECT imaging of malignancy, infectious and inflammatory diseases, cardiac and systemic amyloidosis and radionuclide therapy. He has served as principal investigator (PI) and co-principal investigator on radionuclide therapy trials and was the PI on the Mayo Clinic’s early access protocol for 68Ga-PSMA-11 PET imaging.


Talks by Geoffrey B. Johnson, MD, PhD

Appropriate Use of PSMA PET in Clinical Practice

Geoffrey B. Johnson, MD, PhD, delivers an informative presentation on the appropriate utilization of PSMA PET in clinical practice, delving into various aspects of this advanced imaging technique. Dr. Johnson begins by elucidating the diverse range of prostate cancer PET radiotracers available, with a particular focus on the recently FDA-approved PSMA imaging agents.

In addition to discussing the different types of PET radiotracers, Dr. Johnson also delves into the complex landscape of reimbursement criteria for PSMA PET. Drawing comparisons to traditional imaging methods, he highlights the advantages of PSMA PET in terms of its ability to detect prostate cancer metastases more accurately, paving the way for enhanced diagnostic accuracy and improved treatment decision-making.

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Radioligand Therapy in Prostate Cancer

Geoffrey B. Johnson, MD, PhD, Chair of the Division of Nuclear Medicine at the Mayo Clinic in Rochester, MN, discusses radioligand therapy in prostate cancer. Dr. Johnson briefly reviews the specific activity of this therapy, with a focus on Lutetium-177-PSMA-617.
Dr. Johnson highlights the benefits and tolerable side-effects of Lutetium-177-PSMA-617, and mentions the therapy is approved for patients with metastatic castrate-resistant prostate cancer who have been previously treated with androgen receptor pathway inhibition and taxane-based therapy.

The presentation further explores the process of patient selection for PSMA imaging, with the requirement of at least one lesion that shows higher PSMA expression than the liver. Dr. Johnson showcases post-therapy imaging examples, and discusses the potential of advanced scanning techniques, such as CZT-based scanners, which offer higher sensitivity and faster scans for accurate tracking of therapy response.

Dr. Johnson emphasizes the promising future of radionuclide therapy. He mentions the potential combinations of PSMA therapy with hormonal therapy, chemotherapy, immunotherapy, and external radiation. Additionally, he mentions ongoing trials exploring the use of alpha and beta emitters and the incorporation of different targets.

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Just the Beginning: What’s Next for Radiotheranostics in Prostate Cancer?

Geoffrey B. Johnson, MD, PhD, Chair of the Division of Nuclear Medicine at the Mayo Clinic in Rochester, MN, discusses 177Lu-PSMA-617 treatment for castration-resistant metastatic prostate cancer (mCRPC) along with other advances in theranostics. He reviews how drug treatments target prostate-specific membrane antigen (PSMA) receptors, then highlights the VISION trial which tested 177Lu-PSMA-617 on patients who had previously undergone chemotherapy and hormone therapy. This trial found that patients with advanced prostate cancer had well-tolerated side effects, leading to studies like PSMAfore with patients who had not started chemotherapy. Dr. Johnson points out several drawbacks of 177LuPSMA-617, namely that it does not cure prostate cancer, there are dosing limitations, it is very expensive, and not all prostate cancer patients can be treated with it. He also notes that not all prostate cancer tumors express PSMA thereby reducing the benefit of 177LuPSMA-617. Dr. Johnson then describes combination therapies using hormonal therapy, chemotherapy, immunotherapy, external radiation, cocktail radionuclide therapy, and external radiation. Finally, he presents new technologies like PSMA post-therapy imaging, strategies to improve efficacy of cell binding, and targeting agents such as fibroblast activation protein (FAP) inhibitors.

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