Research ArticleTheranostics

Discovery of 18F-JK-PSMA-7, a PET Probe for the Detection of Small PSMA-Positive Lesions

Boris D. Zlatopolskiy, Heike Endepols, Philipp Krapf, Mehrab Guliyev, Elizaveta A. Urusova, Raphael Richarz, Melanie Hohberg, Markus Dietlein, Alexander Drzezga and Bernd Neumaier
Journal of Nuclear Medicine June 2019, 60 (6) 817-823; DOI: https://doi.org/10.2967/jnumed.118.218495

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Previously known PSMA-specific PET tracers (68Ga-1, 18F-2, and 18F-3) and emerging probes (18F-JK-4-11) investigated in this study.

  • FIGURE 2.
    FIGURE 2.

    Preparation of 18F-2 and 18F-4-10. TEABC = tetraethylammonium bicarbonate.

  • FIGURE 3.
    FIGURE 3.

    Tracer uptake in LNCaP C4-2 cells in relation to 18F-DCFPyL. 18F-DCFPyL uptake after 2 h was normalized to 100%. Only 18F-JK-PSMA-7 shows higher uptake than 18F-DCFPyL. *Significantly different from 18F-DCFPyL at same time point. F7,38 = 1,136; P < 0.0001 for factor “tracer,” post hoc P < 0.05. #Significantly higher than 2-h uptake of same tracer. F1,38 = 6,981; P < 0.0001 for factor “time,” post hoc P < 0.05.

  • FIGURE 4.
    FIGURE 4.

    TBR of PSMA tracers. (A) Sagittal section of PSMA image with SCG and background (Bg) volumes of interest. (B) Graph showing that TBR (SCG/Bg) 60–120 min after injection did not significantly differ among groups (F4,10 = 2.95, P = 0.0756). (C) TBR analyzed for four 30-min frames. *TBE significantly higher for 18F-JK-PSMA-7 than for 68Ga-PSMA-11 (F4,40 = 5.97, P = 0.0102, for factor “tracer,” post hoc P < 0.05). #TBR significantly higher for 18F-JK-PSMA-7 than for 18F-JK-PSMA-8 or 68Ga-PSMA-11 (P < 0.05). TBR of 18F-JK-PSMA-7 and 18F-PSMA-1007 increased significantly over time (F3,30 = 9.12, P = 0.0002, for factor “frame”). †For 18F-JK-PSMA-7, frame 4 was significantly different from frames 1 and 2 (P < 0.05). ‡For 18F-PSMA-1007, frame 4 was significantly different from frame 1 (P < 0.05).

  • FIGURE 5.
    FIGURE 5.

    Acutance (measured for SCG) using different PSMA tracers. (A) Profile plot of 1-pixel profile (Pr in inset) through SCG center. Peak against adjacent background (max) and FWHM were measured. (B) Ratio max/FWHM roughly represents slope of profile plot and reflects acutance. *18F-JK-PSMA-7 and 18F-PSMA-1007 show significantly higher acutance than 18F-DCFPyL, 18F-JK-PSMA-8, or 68Ga-PSMA-11 (F4,10 = 12.77, P = 0.0006; post hoc P < 0.05). %ID = percentage injected dose.

  • FIGURE 6.
    FIGURE 6.

    Resolution of images acquired with different tracers. (A) Profile plot of 1-pixel profile (Pr in inset) through apical pair of DRG. Peak against adjacent background (max) and FWHM were measured for each ganglion. P2–P1 was distance between peaks. (B) Formula R = 2(P2 − P1)/1.7(FWHM1 + FWHM2) yields image resolution. *Image resolution was significantly higher for 18F-JK-PSMA-7 than for 18F-JK-PSMA-8 (F4,10 = 3.80, P = 0.0396; post hoc P < 0.05).

  • FIGURE 7.
    FIGURE 7.

    18F-JK-PSMA-7 scan in patient with relapsed PCa. This 64-y-old patient had serum prostate-specific antigen level of 130 ng/mL. Scan was started 233 min after injection of 384 MBq of 18F-JK-PSMA-7. (Left) Maximum-intensity projection of PET image. (Right) PET/CT images at transverse levels indicated by blue lines.

Tables

  • TABLE 1

    Comparison of Quality of PET Images Obtained with Different Tracers (60–120 Minutes After Injection, n = 3)

    TracerAcutanceResolutionTBR
    18F-DCFPyL0.019 ± 0.0081.002 ± 0.1416.38 ± 1.87
    18F-JK-PSMA-70.075 ± 0.027*1.095 ± 0.042†8.15 ± 1.71
    18F-JK-PSMA-80.021 ± 0.0050.800 ± 0.0324.60 ± 1.30
    18F-PSMA-10070.097 ± 0.025*0.924 ± 0.0746.23 ± 1.88
    68Ga-PSMA-110.024 ± 0.0090.892 ± 0.1464.46 ± 0.08

    • ↵* Significantly higher than 18F-DCFPyL, 18F-JK-PSMA-8, and 68Ga-PSMA-11 (F4,10 = 12.77, P = 0.0006; post hoc P < 0.05).

    • ↵† Significantly higher than 18F-JK-PSMA-8 (F4,10 = 3.80, P = 0.0396; post hoc P < 0.05).

  • TABLE 2

    Tracer Uptake (SUVBW) in Different Tissues 60–120 Minutes After Injection (n = 3 Each)

    TracerSCGSalivary glandLiverBloodBoneBackground
    18F-DCFPyL20.9 ± 8.213.2 ± 5.378.4 ± 29.412.9 ± 3.010.5 ± 3.53.2 ± 0.7
    18F-JK-PSMA-731.3 ± 10.514.4 ± 2.4119.3 ± 8.316.3 ± 4.29.9 ± 1.94.0 ± 1.0
    18F-JK-PSMA-814.4 ± 2.69.0 ± 2.529.0 ± 7.28.6 ± 0.319.2 ± 2.13.2 ± 0.4
    18F-PSMA-100794.8 ± 19.6*62.1 ± 14.2†50.7 ± 4.362.6 ± 10.7‖33.2 ± 9.5#15.9 ± 1.7**
    68Ga-PSMA-1141.0 ± 3.438.4 ± 10.2‡43.7 ± 14.439.6 ± 4.6§18.5 ± 0.69.2 ± 0.6**

    • ↵* Significantly higher than any other (F4,10 = 26.52, P < 0.0001; post hoc P < 0.05).

    • ↵† Significantly higher than any other (F4,10 = 22.06, P < 0.0001; post hoc P < 0.05).

    • ↵‡ Significantly higher than 18F-DCFPyL (F4,10 = 22.06, P < 0.0001; post hoc P < 0.05).

    • ↵ Significantly higher than 18F-JK-PSMA-8 (18F-PSMA-1007 and 68Ga-PSMA-11. F4,10 = 7.83, P = 0.0040; post hoc P < 0.05).

    • ↵‖ Significantly higher than any other (F4,10 = 47.59, P < 0.0001; post hoc P < 0.05).

    • ↵§ Significantly higher than 18F-DCFPyL, 18F-JK-PSMA-7, and 18F-JK-PSMA-8 (F4,10 = 47.59, P < 0.0001; post hoc P < 0.05).

    • ↵# Significantly higher than any other (F4,10 = 12.19, P = 0.0007; post hoc P < 0.05).

    • ↵** Significantly different from all others (F4,10 = 93.81, P < 0.0001; post hoc P < 0.05).

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