This randomized phase III trial examines whether lengthening the dosage interval in an adaptive manner for the prostate cancer drug lutetium 177 Lu PSMA RLT improves quality of life without decreasing lifespan when compared to the standard way this medication is given. This study is for patients with hormone resistant prostate cancer that may have spread from where it first started to nearby tissue, lymph nodes, or distant parts of the body. Hormone resistant prostate cancer often has many cells containing a protein called prostate-specific membrane antigen (PSMA) on their surface. The normal cells in the prostate do not normally express as much PSMA protein on their surface as cancer cells. Lutetium 177 Lu PSMA RLT binds to the PSMA protein on the tumor cells. It builds up in these cells and gives off radiation that may kill them. Typically, this medication is given at the same dose every 6 weeks for up to 6 doses. In this trial, researchers want to see if treatment following the first two doses of lutetium 177 Lu PSMA RLT can be delayed until there is evidence of disease activity. This may be an effective way to improve quality of life without decreasing lifespan in patients with advanced prostate cancer.
The primary and secondary objectives of the study: PRIMARY OBJECTIVES: I. To compare the overall survival (OS) of patients with metastatic castration-resistant prostate carcinoma (mCRPC) receiving prostate-specific antigen (PSA) adaptive dosing of lutetium 177 Lu prostate specific membrane antigen radioligand therapy (177Lu PSMA RLT) to that of patients receiving standard dose 177Lu PSMA RLT every 6 weeks. II. To compare quality of life, as measured by Functional Assessment of Cancer Therapy- Prostate (FACT-P) total scores averaged across the first 30 months, in patients with mCRPC who receive 177Lu PSMA RLT adaptive dosing versus standard dosing. SECONDARY OBJECTIVES: I. To compare the duration of treatment between standard dosing and adaptive dosing. II. To compare the radiographic progression-free survival (rPFS) between the treatment arms. III. To evaluate and compare the toxicity profile of 177Lu PSMA RLT standard dosing and 177Lu PSMA RLT adaptive dosing. IV. To compare the nadir PSA and PSA kinetics between standard and adaptive dosing. V. To compare quality-adjusted life years, which accounts for overall survival and health utility (measured by European Quality of Life Five Dimension Five Level Scale \[EQ-5D-5L\]), between arms. VI. To compare pain severity, as measured by the Brief Pain Inventory - Short Form (BPI-SF), between arms at 12 and 30 months. EXPLORATORY OBJECTIVES: I. To determine the frequency of tumor genomic aberrations (including but not limited to androgen receptor \[AR\] mutation/amplification, deoxyribonucleic acid \[DNA\] repair, retinoblastoma 1 \[RB1\], phosphatase and tensin homolog \[PTEN\], TP53) by circulating-tumor deoxyribonucleic acid (ctDNA) in patients achieving \> 50% PSA decline versus (vs) \< 50% PSA decline after 2 cycles of 177Lu PSMA RLT. II. To evaluate the relationship between OS and initial PSA response (e.g. ≥ 50% decline in PSA level from baseline \[PSA50\] vs ≥ 75% decline in PSA level from baseline \[PSA75\] vs ≥ 90% decline in PSA level from baseline \[PSA90\]) prior to randomization. OUTLINE: PRE-REGISTRATION STEP 0: Patients receive 177Lu PSMA RLT intravenously (IV) on day 1 of each cycle. Cycles repeat every 6 weeks for up to 2 cycles in the absence of disease progression or unacceptable toxicity. Patients who achieve a PSA50 response at cycle (C) 2 day (D) 22 proceed to Step 1. RANDOMIZATION STEP 1: Patients are randomized to 1 of 2 arms. ARM 1: Patients receive 177Lu PSMA RLT IV on day 1 of each cycle. Cycles repeat every 6 weeks for up to 4 cycles in the absence of disease progression or unacceptable toxicity. ARM 2: Starting cycle 2 day 42, patients undergo blood sample collection and PSA monitoring once every 3 weeks (Q3W) in the absence of disease progression or unacceptable toxicity. Patients with either an absolute PSA rise \> 4 ng/dL, PSA rise \> 25% above nadir, or clinical progression receive 177Lu PSMA RLT IV three weeks later. Patients then resume PSA monitoring Q3W with adaptive 177Lu PSMA RLT dosing for up to 4 total doses in the absence of disease progression or unacceptable toxicity. Additionally, all patients undergo blood sample collection, computed tomography (CT), and bone scan throughout the trial and PSMA positron emission tomography (PET) during screening. Patients with a history of brain metastases or with clinical indication also undergo magnetic resonance imaging (MRI) throughout the trial. After completion of study treatment, patients are followed up every 12 weeks until disease progression and then every 6 months thereafter for 5 years following registration.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
1,524
Given IV
Undergo blood sample collection
Undergo PSA monitoring
Undergo CT
Undergo Bone Scan
Undergo PSMA PET Scan
Undergo MRI
Ancillary studies
Overall survival (OS)
Will be calculated as time from randomization until death due to any cause, censoring patients not known to have died at the time of their last follow-up. OS will be compared between the treatment arms using a stratified log rank test
Time frame: Up to 5 years
Quality of life
Will be measured using the Functional Assessment of Cancer Therapy- Prostate (FACT-P) total scores. A repeated measures mixed model will be used to evaluate the between-arm mean difference in FACT-P Total scores across the first 30 months from treatment start. A point estimate of the difference and 95% confidence interval will be reported. Results of formal hypothesis testing will only be reported if adaptive dosing is deemed noninferior to standard dosing with regards to overall survival.
Time frame: Up to 30 months
Duration of treatment
Calculated from the first administration of 177Lu PSMA RLT to the last administration of 177Lu PSMA RLT among randomized patients. Summary measures for the duration of treatment will be recorded by arm and the stratified Wilcoxon rank sum statistic will be used to test whether the treatment duration distribution differs between the standard and adaptive dose treatments.
Time frame: Up to 5 years
Radiographic progression-free survival (rPFS)
Will be defined as time from randomization to the to the date of radiographic disease progression per the Prostate Cancer Clinical Trials Working Group 3 criteria or death from any cause, whichever occurs first. Patients who are alive without a disease progression will be censored at the time of their last disease evaluation. rPFS will be compared between the two treatment arms using a stratified logrank test.
Time frame: Up to 5 years
Rate of Grade 3+ AEs
Will be assessed using Common Terminology Criteria for Adverse Events version 5.0. The proportion of patients that experience a grade 3+ AE regardless of attribution will be summarized as the number and percent of patients by treatment arm.
Time frame: Up to 5 years
Prostate-specific antigen (PSA) response
There will be different thresholds used for PSA response, all measured as change from baseline and confirmed at least 3 weeks later by a second PSA test: PSA50 (a ≥ 50% decline), PSA75 (a ≥ 75% decline), and PSA90 (a ≥ 90% decline).
Time frame: Prior to randomization
Nadir PSA
This is the lowest PSA value observed starting from baseline.
Time frame: Up to 5 years
Pain Severity
This will be measured using the Brief Pain Index Short Form (BPI-SF). Estimates and 95% confidence intervals for the mean difference between treatment arms at 12 and 30 months will be generated using a repeated measures mixed model.
Time frame: Up to 30 months
Quality-adjusted life years
This will be calculated from overall survival and health utility as measured by European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L) using an area under the curve approach. Summary statistics for the area under the curve of each arm and a 95% CI for the difference between arms will be reported.
Time frame: Up to 5 years
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.