Highly Sensitive New Type of Prostate Cancer Scan Gains FDA Approval
What this means for patients: Today, a new type of prostate cancer scan known as 68Ga-PSMA-11 PET was approved by the FDA. This new “PSMA PET” scan can detect prostate cancer metastases much earlier, when they are much smaller, which may help to improve treatment of patients with prostate cancer.
PSMA, short for Prostate Specific Membrane Antigen, is a protein that is found in relatively larger amounts on the surface of prostate cancer cells. PSMA PET is a new imaging technology that allows doctors to “see” PSMA using a PET scanner. Compared to the scans currently used for prostate cancer detection, such as CT, bone scans, and MRI, PSMA PET is more sensitive and can detect much smaller prostate cancer metastases. PSMA PET can now be used for initial and subsequent management decisions in patients with certain types of prostate cancer, in order to determine if and where they have metastases. Researchers are studying how PSMA PET may change treatment and, ultimately, patient outcomes like disease progression and survival.
How does it work? The strategy is based on a small-molecule PSMA binding chemical attached to a radioactive reporter [radioactive element gallium-68 (68Ga)]. This conjugate (PSMA-binder + 68Ga = PET tracer) is introduced into the circulation of a patient where the conjugate accumulates at sites of prostate cancer and the unbound conjugate clears rapidly from circulation. The patient’s body is passed through an imaging camera that records areas where the PET tracer accumulated.
Today’s approval is based on studies led by PCF-funded investigators Dr. Thomas Hope at the University of California, San Francisco, and Dr. Johannes Czernin and Dr. Jeremie Calais at the University of California, Los Angeles. This PCF-funded team conducted a series of clinical trials which demonstrated the improved sensitivity of 68Ga-PSMA-11 PET for detecting sites of recurrent prostate cancer in men with rising PSA levels after surgery or radiation therapy, and for detecting sites of metastases in men newly diagnosed with high-risk prostate cancer.
PCF has invested over $26 million in research on PSMA since inception in 1993. Dr. Neil Bander, now the Bernard and Josephine Chaus Professor of Urological Oncology at Weill Cornell Medicine, first created an antibody to PSMA that launched the field and helped scientists understand the distribution of PSMA in prostate cancer patients.
Now that cancer can be observed earlier, and in smaller amounts, how will this benefit patients? Clinicians are testing whether using PSMA PET to direct radiation therapy in patients who have recurrent disease in the pelvis, or just a few metastases, will improve outcomes.
Eventually the FDA may approve PSMA targeting agents as part of a therapeutic strategy – not just to “see” the cancer, but to deliver drugs or radiation directly to sites of prostate cancer metastasis, killing tumor cells while generally sparing normal tissue. PCF is funding studies of treatments based on PSMA PET detection of metastatic disease. Early investigations are encouraging, but much more work will be needed to definitively link PSMA PET with better outcomes for patients.
With this FDA approval, 68Ga-PSMA-11 PET scanning will be available at only UCLA and UCSF. Radiopharmaceutical companies will likely apply for expedited FDA approval to make 68GaPSMA-11 “kits” so that this technique will eventually be available to more patients throughout the US.
Other PSMA PET imaging agents, including 18F-DCFPyL PET, which was developed by PCF-funded investigators Dr. Martin Pomper, Dr. Steve Cho (now at the University of Wisconsin), and others at Johns Hopkins University, also may become FDA-approved in the near future.
PCF congratulates Drs. Hope, Czernin, and Calais – and all the researchers whose work help to lay the foundation – on this tremendous achievement. We are proud to have supported this important research enterprise all along the way.