Research ArticleClinical Investigation

Prostate-Specific Membrane Antigen PET/CT–Guided, Metastasis-Directed Radiotherapy for Oligometastatic Castration-Resistant Prostate Cancer

John Nikitas, Angela Castellanos Rieger, Andrea Farolfi, Ameen Seyedroudbari, Amar U. Kishan, Nicholas G. Nickols, Michael L. Steinberg, Luca F. Valle, Matthew Rettig, Johannes Czernin and Jeremie Calais
Journal of Nuclear Medicine September 2024, 65 (9) 1387-1394; DOI: https://doi.org/10.2967/jnumed.124.267922

Article Figures & Data

Figures

  • Figure
  • FIGURE 1.
    FIGURE 1.

    CONSORT (Consolidated Standards of Reporting Trials) diagram.

  • FIGURE 2.
    FIGURE 2.

    (A) PFS. (B) Biochemical recurrence-free survival. (C) Freedom from local progression (40 sites). (D) Freedom from distant progression. (E) Freedom from new lines of systemic therapy. (F) OS.

  • FIGURE 3.
    FIGURE 3.

    Change in PSA level from baseline at 6 mo. Biochemical response was defined as PSA decrease ≥ 50% from baseline. *>100% increase.

  • FIGURE 4.
    FIGURE 4.

    (A) Comparison of patients who changed systemic therapy vs. patients who did not. (B) Comparison of patients who had nodal metastasis vs. bone or visceral metastasis. (C) Comparison of patients who had single vs. multiple treated metastases.

  • FIGURE 5.
    FIGURE 5.

    PSMA PET/CT showed new metastases (arrows) in C4 vertebra and right sphenoid bone. Patient underwent metastasis-directed radiotherapy to both sites. Repeat PSMA PET/CT showed resolution of PSMA avidity (arrows) in both treated sites. It also showed multifocal distant disease progression, and patient subsequently started 177Lu-PSMA therapy.

  • FIGURE 6.
    FIGURE 6.

    PSMA PET/CT showed new left sacral metastasis with stable disease in left femur and sternum (arrows). Patient underwent metastasis-directed radiotherapy to sacrum. Repeat PSMA PET/CT showed in-field local failure in sacrum and new progression in left femur and sternum (arrows). Patient underwent reirradiation to sacrum and metastasis-directed radiotherapy to left femur and sternum.

Tables

  • TABLE 1.

    Patient Characteristics at Time of PSMA PET/CT (n = 24 Patients)

    CharacteristicData
    Median age (y)68.8 (IQR, 65.7–71.7)
    Median time since initial diagnosis (y)6.1 (IQR, 3.6–12.0)
    Median time since castration resistance (y)1.6 (IQR, 0.3–3.7)
    Median PSA (ng/mL)1.2 (IQR, 0.4–3.2)
    Initial NCCN risk group (n)
     Localized favorable intermediate risk3 (12.5%)
     Localized unfavorable intermediate risk2 (8.3%)
     Localized high risk9 (37.5%)
     Localized very high risk3 (12.5%)
     Metastatic6 (25.0%)
     Unknown1 (4.2%)
    Prior therapies (n)
     RP + ADT + ARPI5 (20.8%)
     RP + RT + ADT5 (20.8%)
     RP + RT + ADT + ARPI +/− sipuleucel-T7 (29.2%)
     RP + RT + ADT + ARPI + chemotherapy2 (8.3%)
     RT + ADT + ARPI1 (4.2%)
     ADT + ARPI +/− sipuleucel-T3 (12.5%)
     ADT + chemotherapy + 177Lu-PSMA-6171 (4.2%)

    • NCCN = National Comprehensive Cancer Network; RP = radical prostatectomy; RT = radiotherapy.

  • TABLE 2.

    PSMA PET/CT Findings (n = 24 Patients)

    FindingData
    On systemic therapy at time of PSMA PET/CT23 (95.8%)
    Indication for PSMA PET/CT
     Biochemical recurrence15 (62.5%)
     Evaluation of treatment response9 (37.5%)
    T+ disease5 (20.8%)
    N1 disease13 (54.2%)
    M1 disease20 (83.3%)
     M1a only6 (25.0%)
     M1b only12 (50.0%)
     M1a + M1b1 (4.2%)
     M1c only1 (4.2%)
    Staging
     miT0N1M03 (12.5%)
     miT+N1M01 (4.2%)
     miT0N0M1a1 (4.2%)
     miT+N0M1a1 (4.2%)
     miT0N1M1a4 (16.7%)
     miT0N0M1b6 (25.0%)
     miT+N0M1b2 (8.3%)
     miT0N1M1b4 (16.7%)
     miT+N1M1b1 (4.2%)
     miT0N0M1c1 (4.2%)

    • Data are number.

  • TABLE 3.

    PSMA PET/CT Lesions (n = 24 Patients)

    Visible lesionsnNew or progressing lesionsStable lesionsTreated lesionsNontreated lesions
    16 (25.0%)1010
    24 (16.7%)2020
    1 (4.2%)1111
    33 (12.5%)3030
    3 (12.5%)2121
    4 (16.7%)1212
    51 (4.2%)2323
    61 (4.2%)2424
    >101 (4.2%)2>102>10
  • TABLE 4.

    Patient Treatment Characteristics (n = 24 Patients)

    CharacteristicData
    Median time from PSMA PET/CT to metastasis-directed radiotherapy (mo)1.4 (IQR, 0.9–2.8)
    Treated sites (n)
     111 (45.8%)
     210 (41.7%)
     33 (12.5%)
    Concurrent systemic therapy (n)
     ADT4 (16.7%)
     ADT + sipuleucel-T3 (12.5%)
     ADT + ARPI16 (66.7%)
     ADT + ARPI + sipuleucel-T1 (4.2%)
    Change in systemic therapy (n)
     Continued preexisting systemic therapy17 (70.8%)
     Started new systemic therapy7 (29.2%)
  • TABLE 5.

    Treated Site Characteristics (n = 40 Sites)

    CharacteristicProstate/prostate bed (n = 5)Lymph nodes (n = 15)Bones (n = 19)Viscera (n = 1)
    Median size (cm)3.8 (IQR: 2.9–4.0)1.1 (IQR: 0.6–1.1)1.6 (IQR: 1.2–2.2)2.0
    Median SUVmax10.4 (IQR: 4.2–30.2)12.6 (IQR: 6.7–28.7)7.8 (IQR: 3.7–14.5)17.8
    Location
     Prostate3 (60.0%)
     Prostate bed1 (20.0%)
     Bladder base1 (20.0%)
     Pelvic lymph nodes9 (60.0%)
     Retroperitoneal lymph nodes6 (40.0%)
     Pelvic bone8 (42.1%)
     Spine6 (31.6%)
     Ribs/sternum4 (21.1%)
     Skull1 (5.3%)
     Corpus cavernosum1 (100%)
    Treatment modality
     SBRT3 (60.0%)8 (53.3%)19 (100%)0 (0.0%)
     Intensity-modulated radiotherapy2 (40.0%)7 (46.7%)0 (0.0%)0 (0.0%)
     High-dose-rate brachytherapy0 (0.0%)0 (0.0%)0 (0.0%)1 (100%)
    Dose and fractionation
     35–40 Gy in 5 fractions3 (60.0%)
     66–74 Gy in 37 fractions2 (40.0%)
     32 Gy in 4 fractions1 (6.7%)
     30–40 Gy in 5 fractions7 (46.7%)
     55–60 Gy in 23–33 fractions4 (26.7%)
     Unknown3 (20%)
     18 Gy in 1 fraction2 (10.5%)
     18–27 Gy in 3 fractions10 (52.6%)
     25 Gy in 5 fractions1 (5.3%)
     35–50 Gy in 5 fractions6 (31.6%)
     35 Gy in 8 fractions1 (100%)
  • TABLE 6.

    Long-Term Clinical Outcomes (n = 24 Patients)

    OutcomeMedian (mo)1 y (%)2 y (%)4 y (%)
    Rate95% CIRate95% CIRate95% CIRate95% CI
    PFS16.49.8–23.069.750.9–88.538.718.5–58.929.010.0–48.0
    Biochemical recurrence-free survival16.49.8–23.069.750.9–88.538.718.5–58.933.213.2–53.2
    Freedom from local progressionNR94.687.3–10082.970.4–95.473.756.8–90.6
    Freedom from distant progression19.58.8–30.369.750.9–88.538.318.1–58.532.912.9–52.9
    Freedom from new lines of systemic therapy29.07.6–50.482.867.5–98.152.331.9–72.739.217.2–61.2
    OSNR95.787.3–10091.179.3–10068.845.1–92.5

    • NR = not reached.

Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Bookmark this article

Jump to section

Keywords