PMC10262655_01
Staging and posttherapy MIP. (a) Staging [68Ga]Ga-PSMA-11 PET/CT study demonstrates intense PSMA uptake in multiple osseous and nodal metastases. There is relatively reduced PSMA uptake in the right kidney, consistent with postobstructive nephropathy. [18F]F-FDG PET/CT study demonstrates no discordant lesions (areas of disease with no significant [68Ga]Ga-PSMA-11 uptake). (b) Posttherapy quantitative [177Lu]Lu-SPECT/CT at 24 h after each cycle of treatment showed a progressive reduction in volume and avidity of multiple PSMA-avid lesions, with many resolving at the fourth posttherapy scan. Most lesions cannot be identified by the fourth cycle, with minimal uptake in the left scapula (red arrowhead).. MIP, maximum intensity projections; PET/CT, Positron emission tomography with computed tomography; PSMA, Prostate-specific membrane antigen.
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PSA of 262 mug/L and a PSA doubling time of 1.4 months. Positron emission tomography with computed tomography (PET/CT) demonstrated extensive nodal disease above and below the diaphragm and numerous bony metastases (Figure 1). Prior to treatment with [177Lu]Lu-PSMA-617, a MAG3 renogram to evaluate renal function demonstrated an obstructed right kidney that contributed 13% to total renal function, and the left kidney contributed the remaining 87% (Supplemental Figure 1). Additionally, functional imaging with [177Lu]Lu-PSMA-617 showed a marked reduction in size and avidity of multiple PSMA-avid lesions, many of which were no longer identified (Figure 1 and 2).
[68Ga]Ga-PSMA-11 PET/CT and posttherapy [177Lu]Lu-SPECT/CT imaging. (a) Staging [68Ga]Ga-PSMA-11 PET/CT study demonstrates an intensely PSMA-avid nodal mass compressing the right ureter. (b-e) Posttherapy quantitative [177Lu]Lu-SPECT/CT at 24 h after each cycle. Between staging and the first posttherapy scan, a right ureteric stent was inserted (light blue arrow on CT images). The patient was treated 6 weeks after staging, and the right-sided nodal mass obstructing the ureter has increased in size. Between the first posttherapy scan and the fourth posttherapy scan, the nodal mass has decreased from 6.0 cm x 3.3 cm to 2.1 cm x 1.4 cm. Posttherapy scans are acquired 24 h after administering [177Lu]Lu-PSMA-617 therapy. However, it can take several weeks for PSMA-avid prostate cancer to respond to [177Lu]Lu-PSMA-617 therapy. As such, a posttherapy scan represents the response to treatment from the prior cycle(s), not the current one. The decrease in size of the nodal mass on the fourth posttherapy scan reflects the last three cycles of therapy.. PET/CT, Positron emission tomography with computed tomography; PSMA, Prostate-specific membrane antigen.
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Staging [18F]F-FDG and [68Ga]Ga-PSMA-11 PET/CT, as well as 24-h posttherapy quantitative [177Lu]Lu-PSMA-617 single photon emission computed tomography with CT (SPECT/CT) studies, demonstrated right renal outflow tract obstruction secondary to a conglomerate nodal mass measuring 5.8 cm x 2.5 cm compressing the ureter (Figure 2) with a volumetric doubling time of 2.3 months. SPECT/CT studies were acquired 24 and 96 h post [177Lu]Lu-PSMA-617 to define accurate renal dosimetry.   The mean absorbed dose for metastatic prostate cancer was 26.1 Gy, while the mean renal absorbed dose was 1.8 Gy for the left kidney and 1.2 Gy for the right kidney and provided reassurance that further cycles could be safely administered (Supplemental Figure 2). Additionally, functional imaging with [177Lu]Lu-PSMA-617 showed a marked reduction in size and avidity of multiple PSMA-avid lesions, many of which were no longer identified (Figure 1 and 2).
PSA response to [177Lu]Lu-PSMA-617 therapy. Interval decline in PSA with response to four cycles of therapy. The patient has been followed for 1 year without evidence of disease recurrence. Actual PSA measurements are denoted by blue circles.. PSA, prostate-specific antigen.
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Following four cycles of [177Lu]Lu-PSMA-617 therapy, the patient's PSA level declined sharply, with a 97% reduction in the serum PSA (Figure 3) and a corresponding 61% reduction in measurable tumor volume (Table 1), by RECIST 1.1 criteria. Throughout therapy and 12 months of follow-up, his eGFR remained between 24 and 30 mL/min/1.73 m2 with no evidence of [177Lu]Lu-PSMA-617-induced acute or chronic nephrotoxicity (Supplemental Figure 3).