There is evidence that Actinium-225 Prostate-Specific Membrane Antigen (225Ac-PSMA) has a potentially higher level of efficacy than 177 Lutetium Prostate-Specific Membrane Antigen (177Lu-PSMA) as a radioligand therapy. This single center, pilot study will compare differences in the mechanisms of actinium-225 and lutetium-177 radioligand therapies (RLT) in participants with high or very high risk localized or locoregional prostate cancer planning on undergoing a prostatectomy.
PRIMARY OBJECTIVES: 1. Compare the tumor absorbed dose between 177Lu-PSMA-617 and 225Ac-PSMA-617. 2. Compare the immunologic priming of 177Lu-PSMA-617 and 225Ac-PSMA-617 with controls in prostatectomy specimens. SECONDARY OBJECTIVES: 1. Determine the safety and tolerability of neoadjuvant 177Lu-PSMA-617 and 225Ac-PSMA-617 in participants with high or very high-risk prostate cancer planning to undergo radical prostatectomy. 2. Estimate PSA response for 177Lu-PSMA-617 and 225Ac-PSMA-617 treatment. 3. Estimate the rate of pathologic response in participants treated with 177Lu-PSMA-617 and 225Ac-PSMA-617. EXPLORATORY OBJECTIVES: 1. Determine the relationship between percent cell necrosis and tumor absorbed dose for both 177Lu-PSMA-617 and 225Ac-PSMA-617. 2. Compare the heterogeneity of cell necrosis for 177Lu-PSMA-617 and 225Ac-PSMA-617. 3. Compare messenger ribonucleic acid (mRNA) expression profiles of tumor treated with 177Lu-PSMA-617, 225Ac-PSMA-617, and controls. 4. Compare mRNA expression profiles of tumors in participants who achieve a PSA50 response and those that do not. 5. Compare mRNA expression profiles of tumors from archival tissue and at time of prostatectomy. 6. Compare the percent cell necrosis between participants receiving a single cycle of PSMA RLT versus participants receiving two cycles of PSMA RLT. 7. Compare the change in uptake on PSMA Positron Emission Tomography (PET) to PSA response and percent cell necrosis. 8. Descriptively evaluate cell necrosis at the tumor margins. 9. Evaluate changes in peripheral immune activation markers following radioligand therapy. 10. Compare the kidney absorbed dose (in Gray) between patients receiving 177Lu-PSMA-617 and those receiving 225Ac-PSMA-617, using post-treatment SPECT imaging acquired 7 days after administration of the first dose. 11. Evaluate feasibility of PET for imaging actinium-225. OUTLINE: Participants will be assigned to 1 of 2 cohorts to receive 177Lu-PSMA-617 or 225Ac-PSMA-617. Additional participants undergoing prostatectomy without RLT will be enrolled as a control group. Participants enrolled in the RLT cohorts will receive 1 to 2 cycles of PSMA radioligand therapy up to 6 weeks apart before a scheduled, non-investigational, prostatectomy four weeks after PSMA radioligand therapy. Participants receiving RLT will be followed up for a safety assessment 6 weeks after surgery and for up to 60 months after prostatectomy for long term follow-up. Participants in the prostatectomy only cohort will have safety and long-term follow-up performed as part of clinical care up to 24 months after surgery.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
45
Given intravenously (IV) or intra-arterially (IA)
Given IV or IA
Undergo non-investigational surgical procedure to remove prostate.
Whole prostate tissue will be collected for correlative research at time of prostatectomy.
Imaging procedure
Blood samples will be obtained for research purposes
University of California, San Francisco
San Francisco, California, United States
RECRUITINGMean of tumor absorbed dose (Cohorts 1 and 2)
The mean tumor absorbed dose on post-treatment SPECT imaging within 7 days of the first radioligand treatment (RLT) will be obtained by using MIM Software to measure absorbed dose and researchers will manually segment activity in the dominant prostate tumor while carefully excluding any activity within the bladder using a threshold of 5 Gray. Using this segmented volume, the mean dose within the tumor in Gray for each participant and standard deviation will be calculated and reported descriptively for Cohorts 1 and 2. A two-sample t-test comparing the dose between Cohort 1 and Cohort 2 and Analysis of Variance (ANOVA) model to compare the dose between different treatment/fractionation modalities within each cohort will be performed.
Time frame: 1 week
Rate of Cluster of differentiation 3 positive (CD3+) T cell infiltration
Immunohistochemistry will be performed using standard methods, and stained slides will be scanned using an automated microscope scanner. Five randomly selected fields (0.25 mm\^2) from each participant's primary tumor will be captured. Using color-specific algorithms, CD3+ cell counts will be determined, and the mean of each of the five quantified fields will be used. We will use a two-sample t-test or ANOVA model comparing the CD3+ cell counts between Cohort 1 and Cohort 2 with participants who have not undergone prostatectomy enrolled in the biospecimen protocol, respectively.
Time frame: 1 day, at time of prostatectomy
Proportion of participants with reported treatment-emergent adverse events (Cohorts 1 and 2)
The proportion of participants with treatment-emergent adverse events, as classified by the National Cancer Institute Common Terminology Criteria for Adverse Events version 5 (NCI CTCAE v5.0) will be reported for participants receiving RLT.
Time frame: Up to 6 weeks after last PSMA RLT administration
Proportion of participants with perioperative complications
The Clavien-Dindo classification is a widely used system for grading and classifying surgical complications. The Proportion of participants with documented perioperative complications following prostatectomy per the Clavien-Dindo classification will be reported.
Time frame: Up to 6 weeks after prostatectomy
Median scores on the xerostomia-quality-of-life-scale (XeQoLS)
The XeQoLS questionnaire measures the effects of salivary gland dysfunction and xerostomia on the four major domains of oral health-related quality of life: physical, pain, personal, and social. The questionnaire consists of 15 items, each rated on a 0-to-4 point Likert scale, with higher scores indicating more severe symptom burden. Median scores for each domain and global score and interquartile ranges will be reported.
Time frame: Up to 12 months after prostatectomy
Proportion of participants with 50% decrease in level of prostate specific antigen (PSA50)
The proportion of participants who achieve a greater than 50% decline from baseline PSA drawn prior to Cycle 1 Day 1 (C1D1), up to the day of prostatectomy, will be descriptively reported along with 95% binomial confidence interval. It will be compared between the two treatment Cohorts using a Fischer's test.
Time frame: Up to 8 weeks
Proportion of participants with complete pathologic response
Using the prostatectomy specimen, a board certified pathologies will determine pathologic complete response for each participant at time of prostatectomy. The pathologic response to the treatment in the prostate will be evaluated by percentage (0%, \<10%, 10-25%, 50-75%, 75-100%) of viable tumor in the formalin-fixed paraffin embedded specimen. Complete pathologic response will be defined as no viable tumor (0%), and minimal residual disease will be defined as \<10% of viable tumor. The number of participants in Cohorts 1 and 2 with complete pathologic response or minimal residual disease will be counted and the number of participants between the two cohorts will be compared using a Fisher's exact test. The proportion of complete pathologic response and minimal residual disease will be descriptively reported along with 95% binomial confidence interval.
Time frame: 1 day, at time of prostatectomy
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