Fluciclovine (Axumin) for Prostate Cancer Imaging

 

  1. Prostate cancer - biochemically recurring prostate cancer (BRC)
    1. Regulate amino acid transporter
      1. Glutamine transporters ASCT2 and LAT1 are the most prevalent
      2. Transporters are found in larger quantities on the surface of prostate tumor cells
      3. Thse transporters assist in the spread of disease
  2. Axumin is a PET 18F radiopharmaceutical used to diagnose, stage, re-stage prostate cancer. A four minute video is available at https://www.axumin.com/about/moa
    1. Mechanism of uptake
      1. Tracer is a synthetic amino acid that mimics glutamine
      2. Transported into the cancer cells
      3. Since it is not incorporated into the cancer cells, over time, it washes out of the cell
    2. Uptake
      1. Occurs in the prostate bed, lymph nodes, and bone
      2. It identifies all prostate cancers 77% and 90% are found outside the prostate bed
      3. Uptake appears to be related to PSA levels
        1. Teyateeti A, et al - In a small study of patients with undetectable PSA levels
          1. 4 of 324 were positive
          2. Positive had a Gleason score of 7 or higher
          3. Staging was T3-T4
        2. Scarsbrook AF - Studied the management of biochemical recurrence (BCR) in 104 patients
          1. Disease was detected in 58 of 104
          2. Only 1 of three patients were positive with a PSA value of < 1.0 ng/mL
          3. 93% were positive if PSA value was > 2.0 ng/mL
      4. Calsis J -68Ga-PSMA-11 vs 18F-Fluciclovine - future direction?
        1. In a small study of 10 patients
        2. These two radiotracers were compared and the results indicated that PSMA tracer
        3. Further evaluation needs to be initiated
    3. Procedure guideline for prostate cancer imaging (version 1.0)
      1. Indications
        1. Assessing BCR appears to indicate that any PSA above >0.2 ng/mL requires further assessment and possible therapy
        2. Sensitivity of Axumin increases with higher Gleason score levels
        3. Cancer within the prostate bed has a high sensitivity and low specificity
        4. Outside the prostate bed there is a high to mid sensitivity (55%) and high specificity (97%)
        5. Regional distal mets varied based on PSA levels in a study of almost 600 patients
          1. 0.8 to 2.03 ng/mL sensitivity ~60% (21 - 39% distal)
          2. 2.04 to 6 ng/mL sensitivity ~75% (45% distal)
          3. >6 ng/mL 85% (60% distal)
        6. High correlation to metastatic bone, however, a bone scan should be done even when Axumin is negative
        7. Axumin has a major effect in altering radiation therapy to the prostate bed (reducing it). Why?
      2. Uptake
        1. Raped uptake occurs in cancer cells - peak tumor to surrounding tissue occurs 4 to 10 minutes post injection and plateaus at 30 minutes
        2. Washout begins at 15 minutes with 61% reduction at 90 minutes
        3. Lymph node avidity has rapid uptake and a faster washout when compared to prostate cancer
      3. Imaging protocol and processing
        1. Patient should be on the imaging table when receiving a bolus injection of the tracer
        2. Injection is preferred in the right arm which should be elevated after the injection is complete
        3. Start transmission scan
        4. At 3 - 5 minutes post inject the PET acquisition should begin
        5. Zero to five minute dynamics can be taken over the prostate bed
        6. Body scan should start at the base of prostate bed to include inguinal lymph nodes to the base of the skull
        7. If lower extremities are required then complete this as the second part of the imaging procedure
        8. If scanning is delayed for up to 30 minutes then imaging time per bed should also be increased
        9. CT with contrast does not appear to help in the diagnosis
        10. TOF is recommended
        11. Reconstruction with a point sped function (PSF) is recommended
        12. CT bone window is recommended

        13. Normal distribution of Axumin with no disease present - tissue uptake occurs in pancreas and liver (greatest intensity), salivary and pituitary (moderate), muscle and bone marrow (moderate to mild)

        14. Biodistribution of Axumin in normal and abnormal tissue

        15. Positive Axumin with lymph node involvement
        16. False positive findings include - benign prostatic hyperplasia, post-radiation inflammation, and fibrosis. Ringworm, and musculoskeletal or skin
    Reference
    Axumin Website for Healthcare Professionals - https://www.axumin.com/about/moa
    18 F-fluciclovine PET-CT and 68 Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: a prospective, single-centre, single-arm, comparative imaging trial. Calais J, et al. Lancet Oncol. 2019 Sep;20(9):1286-1294. doi: 10.1016/S1470-2045(19)30415-2. Epub 2019 Jul 30.
    Is There Any Role for 18F-Fluciclovine PET/CT in the Presence of Undetectable PSA in Prostate Cancer Patients After Definitive Treatment? Clin Nucl Med 2020 Sep;45(9):672-678. doi: 10.1097/RLU.0000000000003122.
    Effect of 18 F-Fluciclovine Positron Emission Tomography on the Management of Patients With Recurrence of Prostate Cancer: Results From the FALCON Trial. Scarsbrook AF, et. al. Int J Radiat Oncol Biol Phys . 2020 Jun 1;107(2):316-324. doi: 10.1016/j.ijrobp.2020.01.050. Epub 2020 Feb 14.
    Comparison of Ga-PSMA-11 vs 18F-Fluciclovine PET/CT in a Case Series of 10 Patients with Prostate Cancer Recurrence. Calais J, et al. Published online: J Nucl Med. 2018;59:789-794. Doi: 10.2967/jnumed. 117.203257
    Exellent slide presentaoitn - Fluciclovine: 1st FDG Approved F-18 Imaging Agent For REcurrent Prostate Cancer, by Kevin P Banks, MD
     
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