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E1797. Novel Use of Prostate Specific Membrane Antigen (PSMA) in PET/MRI Evaluation of Gynecologic Cancers
Authors
  1. Joanna Kusmirek; University of Wisconsin
  2. Brittany Lees; University of Wisconsin
  3. Lisa Barroilhet; University of Wisconsin
  4. Steve Cho; University of Wisconsin
  5. Alan McMillan; University of Wisconsin
  6. Elizabeth Sadowski; University of Wisconsin
Objective:
Folate hydrolase 1/glutamate carboxypeptidase II (PSMA) is expressed in the neovasculature of both prostate and non-prostate cancers. F18-DCFPyL PSMA PET imaging demonstrates very high tumor-to-background ratios in prostate, lung, and renal cancers. A recent immunohistochemistry study demonstrated high PSMA expression in gynecologic tumors and not in normal tissue. Our study evaluates PSMA 18F-DCFPyl PET/MRI in gynecologic cancers and normal endometrial and ovarian tissues.

Materials and Methods:
IRB-approved prospective pilot study in women with and without endometrial and ovarian cancers. Consenting women underwent PSMA F18-DCFPyl PET/MRI and standard of care surgery. For normal and pathologic tissues, the average +/-SD and range are reported for the PET SUVmax in areas of enhancement on the MRI. Student t-test statistical analysis was performed to detect a difference between normal and pathologic tissues.

Results:
14 subjects have been enrolled: 5 normal subjects; 2 with endometrial cancers; 3 with benign ovarian tumors; 3 with ovarian cancers. SUVmax blood pool=1.7+/-0.5 SUVmax endometrium=4.3+/-0.9 vs SUVmax endometrial cancer=9.8+/-1.9 (P=0.0003) SUVmax ovarian parenchyma=2.4+/-0.9 vs SUVmax ovarian cancer=5.6+/-3.0 (P=0.008) SUVmax benign ovarian tumor=2.9+/-0.8 vs SUVmax ovarian cancer=5.6+/-3.0 (P=0.11)

Conclusion:
On PSMA 18F-DCFPyL PET/MR imaging there is a significantly lower SUVmax seen in normal endometrial tissue, normal ovarian tissue and benign ovarian neoplasms, compared to gynecologic cancer. This study is ongoing with continued enrollment to validate these initial observations. This data may contribute to development of targeted treatment for aggressive gynecologic malignancies resistant to traditional chemotherapy.