Case of the Month
PSMA PET CT in Prostate Cancer
Presented by: Jaideep S. Sohi, MD   •  American Molecular Imaging, Inc.

Disclaimer: The views in this case study are those of the author and are provided for medical educational purposes. Representative patient scan only, individual results may vary.

History: Patient is a 72-year-old male with history of prostate carcinoma, diagnosed in 2020. Gleason 4+3 =7. Status post radiation therapy, ADT and Lu-PSMA therapy. Presents now with rising PSA values, most recently at 5.6 ng/dl.

Image Findings: 68Ga-PSMA-11 PET (Illuccix™) demonstrates multiple left neck base lymph nodes with increased uptake (figure 1) A biopsy proved results to be metastatic prostate carcinoma. Of note, no focal abnormal uptake is present at the prostate gland (figure 2) or abdominopelvic lymph nodes.

Figure 1

Figure 1: Focal intense uptake in several adjacent left neck base lymph nodes.

Figure 2

Figure 2: No focal increased PSMA uptake is seen involving the prostate gland.

Case Summary: Whole body Illuccix™ PSMA PET demonstrates evidence of distant metastatic disease without evidence for locally recurrent or locoregional metastasis.

Teaching Point: The utility of (Illuccix™) PSMA PET for whole body evaluation of recurrent/metastatic prostate carcinoma is demonstrated in this case with evidence of distant nodal metastasis. This would not have been visualized on CT imaging which typically includes the abdomen and pelvis in the field-of-view for staging and restaging purposes.

 

Indications and Usage

Illuccix®, after radiolabeling with Ga 68, is a radioactive diagnostic agent indicated for positron emission tomography (PET) of prostate-specific membrane antigen (PSMA) positive lesions in men with prostate cancer:

  • with suspected metastasis who are candidates for initial definitive therapy
  • with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level

Important Safety Information

WARNINGS AND PRECAUTIONS

Risk for Misdiagnosis
Image interpretation errors can occur with gallium Ga 68 gozetotide PET. A negative image does not rule out the presence of prostate cancer and a positive image does not confirm the presence of prostate cancer. The performance of gallium Ga 68 gozetotide for imaging of biochemically recurrent prostate cancer seems to be affected by serum PSA levels and by site of disease. The performance of gallium Ga 68 gozetotide for imaging of metastatic pelvic lymph nodes prior to initial definitive therapy seems to be affected by Gleason score. Gallium Ga 68 gozetotide uptake is not specific for prostate cancer and may occur with other types of cancer as well as non-malignant processes such as Paget’s disease, fibrous dysplasia, and osteophytosis. Clinical correlation, which may include histopathological evaluation of the suspected prostate cancer site, is recommended.

Indications and Usage

Illuccix®, ILLUCCIX, after radiolabeling with Ga 68, is for positron emission tomography (PET) of prostate-specific membrane antigen (PSMA) positive lesions in men with prostate cancer:

  • with suspected metastasis who are candidates for initial definitive therapy
  • with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level
  • For selection of patients with metastatic prostate cancer, for whom lutetium Lu 177 vipivotide tetraxetan PSMA-directed therapy is indicated

Important Safety Information

WARNINGS AND PRECAUTIONS

Risk for Misinterpretation
Image interpretation errors can occur with ILLUCCIX PET. A negative image does not rule out the presence of prostate cancer, and a positive image does not confirm the presence of prostate cancer. Gallium Ga 68 gozetotide uptake is not specific for prostate cancer and may occur with other types of cancer as well as non-malignant processes such as Paget’s disease, fibrous dysplasia, and osteophytosis. Clinical correlation, which may include histopathological evaluation of the suspected prostate cancer site, is recommended.

Imaging Prior to Initial Definitive or Suspected Recurrence Therapy
The performance of ILLUCCIX for imaging of biochemically recurrent prostate cancer seems to be affected by serum PSA levels and by site of disease. The performance of ILLUCCIX for imaging of metastatic pelvic lymph nodes prior to initial definitive therapy seems to be affected by Gleason score.

Imaging to Select Patients for Lutetium Lu 177 Vipivotide Tetraxetan Therapy
The interpretation of ILLUCCIX PET may differ depending on imaging readers. ILLUCCIX PET interpretations to select patients for lutetium Lu 177 vipivotide tetraxetan therapy may be more consistent when judging gallium Ga 68 gozetotide uptake in any one tumor lesion compared to judging uptake for all lesions larger than size criteria. Multidisciplinary consultation to select patients for lutetium Lu 177 vipivotide tetraxetan therapy is recommended, particularly for ILLUCCIX imaging that a single reader finds borderline or difficult to interpret, or when patient eligibility hinges only on judgment of gallium Ga 68 gozetotide uptake for all lesions larger than size criteria.

Radiation Risks
Gallium Ga 68 gozetotide contributes to a patient’s overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk for cancer. Ensure safe handling to minimize radiation exposure to the patient and healthcare providers. Advise patients to hydrate before and after administration and to void frequently after administration.

ADVERSE REACTIONS

The safety of gallium Ga 68 gozetotide was evaluated in 960 patients in the PSMA-PreRP and PSMA-BCR studies, each receiving one dose of gallium Ga 68 gozetotide. The average injected activity was 188.7 ± 40.7 MBq (5.1 ± 1.1 mCi). The most commonly reported adverse reactions were nausea, diarrhea, and dizziness, occurring at a rate of <1%.

In the VISION study, 1003 patients received one dose of gallium Ga 68 gozetotide intravenously with the amount of radioactivity 167.1 ± 23.1 MBq (4.52 ± 0.62 mCi). Adverse reactions occurring at ≥0.5% in patients with metastatic prostate cancer who received gallium Ga 68 gozetotide injection in the clinical study were fatigue (1.2%), nausea (0.8%), constipation (0.5%), and vomiting (0.5%).

Adverse reactions occurring at a rate of < 0.5% in the VISION study were diarrhea, dry mouth, injection site reactions, including injection site hematoma and injection site warmth and chills.

DRUG INTERACTIONS

Androgen deprivation therapy and other therapies targeting the androgen pathway

Androgen deprivation therapy (ADT) and other therapies targeting the androgen pathway, such as androgen receptor antagonists, can result in changes in uptake of gallium Ga 68 gozetotide in prostate cancer. The effect of these therapies on performance of gallium Ga 68 gozetotide PET has not been established.

You are encouraged to report suspected adverse reactions of prescription drugs to the FDA. Visit MedWatch at www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report adverse reactions to Telix by calling 1-844-455-8638 or emailing pharmacovigilance@telixpharma.com.

Please note that this information is not comprehensive.

Please see  full Prescribing Information.

References: 1. Illuccix (kit for the preparation of gallium Ga 68 gozetotide injection) prescribing information. 2. Griffeth LK. Use of PET/CT scanning in cancer patients: technical and practical considerations. Proc (Bayl Univ Med Cent). 2005;18(4):321-330. 3. Dorff TB, Fanti S, Farolfi A, Reiter RE, Sadun TY, Sartor O. The evolving role of prostate-specific membrane antigen-based diagnostics and therapeutics in prostate cancer. Am Soc Clin Oncol Educ Book. 2019;39:321-330. 4. Velikyan I. 68Ga-based radiopharmaceuticals: production and application relationship. Molecules. 2015;20(7):12913-12943. 5. Massat MB. Nuclear medicine prepares for greater 68Ga demand. Appl Radiol. 2021;50(2):30-31. https://appliedradiology.com/articles/nuclear-medicine-prepares-for-greater-ga-68-demand. Accessed May 13, 2022. 6. ARTMS and Telix Pharmaceuticals announce successful production of PSMA-11 with cyclotron produced 68Ga from a solid target [news release]. Telix Pharmaceuticals; January 12, 2021. https://telixpharma.com/news-media/artms-and-telix-pharmaceuticals-announce-successful-production-of-68ga-psma-11-with-cyclotron-produced-68ga-from-a-solid-target/. Accessed May 13, 2022. 7. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Prostate Cancer V.4.2022. © National Comprehensive Cancer Network, Inc. 2022. All rights reserved. Accessed May 12, 2022. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way. 8. Jadvar H, Calais J, Fanti S, et al. Appropriate use criteria for prostate-specific membrane antigen PET imaging. J Nucl Med. 2022;63(1):59-68. 9. Eiber M, Fendler WP, Rowe SP, et al. Prostate-specific membrane antigen ligands for imaging and therapy. J Nucl Med. 2017;58(suppl 2):67S-76S. 10. Ristau BT, O’Keefe DS, Bacich DJ. The prostate-specific membrane antigen: lessons and current clinical implications from 20 years of research. Urol Oncol. 2014;32(3):272-279. 11. Maurer T, Gschwend JE, Rauscher I, et al. Diagnostic efficacy of (68)Gallium-PSMA positron emission tomography compared to conventional imaging for lymph node staging of 130 consecutive patients with intermediate to high risk prostate cancer. J Urol. 2016;195(5):1436-1443.