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FTT-PET and ctDNA to Predict Response to PARP Inhibitor Therapy in Metastatic Prostate Cancer

This study is looking at how well two tests, [18F]fluorthanatrace (FTT-PET) imaging and EnhanceAR-Seq (a blood test), can predict if PARP inhibitor therapy will work for men with metastatic prostate cancer (cancer that has spread). Researchers want to see if these tests can help understand how tumors respond to treatment and identify changes in genes that might lead to resistance. You may be able to join if you are an adult male with metastatic prostate cancer and have specific genetic changes (like in the ATM, BRCA1, BRCA2, or PALB2 genes). The study will measure how accurately FTT-PET and EnhanceAR-Seq predict treatment response, with measurements taken before and during PARP inhibitor therapy. The study aims to enroll 75 participants, but the current recruitment status is unclear.

Study design
This is an open-label (meaning you and your doctors will know what treatments you are receiving) diagnostic imaging study. It is designed to assess the use of FTT-PET and EnhanceAR-Seq in predicting response to therapy, with a planned enrollment of 75 participants.
What's involved
You will receive an intravenous (IV) injection of [18F]fluorthanatrace (FTT) and then undergo a PET/CT scan about 60 minutes later. You will also have about 30 mL of blood drawn for the EnhanceAR-Seq test. These procedures will occur at baseline (before PARP inhibitor therapy) and after the first cycle of therapy (about 28 days), and for blood tests, also at 12 weeks and at progression if applicable.
Compensation
Not stated in the trial record.
Follow-up
The study will follow your response to therapy for at least 28 days after the first cycle, and for blood tests, up to 12 weeks after starting PARP inhibitor therapy, and at progression if it occurs (estimated total time 6 months).

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07723651

[18F]Fluorthanatrace - Positron Emission Tomography (FTT-PET) and ctDNA to Predict Response to PARP Inhibitor Therapy in Metastatic Prostate Cancer (mPC)

Not Yet Recruiting
PHASE2Ages 18+InterventionalDiagnostic
Washington University School of Medicine
~75 participants
Updated 2026-07-23 on ClinicalTrials.gov
What's tested:1-(4-(2-Fluoroethoxy)phenyl)-8,9-dihiydro-2,7,9a-triazabenzo[cd]azulen-6(7H)-oneFTT-PET/CTEnhanceAR-Seq

At a glance

Recruiting sites
0 of 3 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Prediction performance of FTT-PET as measured by concordance index (C-index)
Measured over At baseline prior to PARPi therapy and post cycle 1 (estimated total time 28 days)
+11 more outcomes measured

Conditions

Metastatic Prostate Cancer
Prostate Cancer

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Where it's being run

3 sites across 3 states
Missouri1
Pennsylvania1
Texas1

Study leadership

  • Farrokh Dehdashti, MD · PRINCIPAL_INVESTIGATOR · Washington University School of Medicine

Who to contact

Farrokh Dehdashti, MD
[email protected]
314-362-1474
Email the study team

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Eligibility criteria

Inclusion

Adult male patients 18 years of age or older
mCRPC with confirmed germline or somatic HRR (such as ATM, ATR, BRCA1, BRCA2, CDK12, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2, or RAD51C for Talazoparib/enzalutamide and ATMm, BRCA1m, BRCA2m, BARD1m, BRIP1m, CDK12m, CHEK1m, CHEK2m, FANCLm, PALB2m, RAD51Bm, RAD51Cm, RAD51Dm, RAD54Lm; gBRCA1m, gBRCA2m; ATMm, BRCA1m, BRCA2m for Olaparib +/- abiraterone) mutations who are scheduled for SOC PARPi therapy.
Lesion size of at least 1.0 cm in longest dimension by imaging. If non-measurable, lesion needs to be clearly detected on other imaging studies such as bone scintigraphy, FDG-PET, PSMA-PET or MRI.
On continuous androgen deprivation therapy (ADT) with appropriately suppressed castrate testosterone levels of \< 50 ng/dL, or prior bilateral orchiectomy.
Serum PSA of 2 ng/mL or greater.
Eastern Cooperative Oncology Group (ECOG) performance status of 0-2.
Able to give informed consent

Exclusion

Receipt of prior PARP inhibitor therapy in any disease setting.
Patients with other invasive malignancies, with the exception of non-melanoma skin cancer, who had (or have) any evidence of the other cancer that is active at the time of enrollment.
Unable to tolerate approximately 30 min (total time) of PET/CT imaging.

What this trial measures

  • Prediction performance of FTT-PET as measured by concordance index (C-index)At baseline prior to PARPi therapy and post cycle 1 (estimated total time 28 days)

    Prediction performance of FTT-PET in predicting participant response to PARPi therapy will be assessed by concordance index (C-index). The C-index is mathematically calculated as the number of concordant pairs divided by the number of comparable pairs. A C-index of 1 indicates perfect ranking, values close to 0.5 indicate random prediction, and values between 0.5 and 1 suggest some predictive ability (a value below 0.5 can be reversed by switching the response's 0 and 1 labels).

  • Prediction performance of FTT-PET as measured by area under the receiver operating characteristic (ROC) curveAt baseline prior to PARPi therapy and post cycle 1 (estimated total time 28 days)

    Prediction performance of FTT-PET in predicting participant response to PARPi therapy will be assessed by the area under the ROC curve. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes the model performance. A higher AUC value indicates better performance.

  • Prediction performance of EnhanceAR-Seq ctDNAas measured by concordance index (C-index)At baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Prediction performance of EnhanceAR-Seq ctDNA analysis in predicting participant response to PARPi therapy will be assessed by concordance index (C-index). The C-index is calculated as the number of concordant pairs divided by the number of comparable pairs. A C-index of 1 indicates perfect ranking, values close to 0.5 indicate random prediction, and values between 0.5 and 1 suggest some predictive ability (a value below 0.5 can be reversed by switching the response's 0 and 1 labels).

  • Prediction performance of EnhanceAR-Seq ctDNA as measured by area under the receiver operating characteristic (ROC) curveAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Prediction performance of EnhanceAR-Seq ctDNA analysis in predicting participant response to PARPi therapy will be assessed by the area under the ROC curve. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes the model performance. A higher AUC value indicates better performance.

  • Prediction performance of FTT-PET and EnhanceAR-Seq ctDNA collectively as measured by concordance index (C-index)At baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), and at progression if applicable (estimated total time 6 months)

    Prediction performance of FTT-PET and EnhanceAR-Seq ctDNA analysis collectively in predicting participant response to PARPi therapy will be assessed by concordance index (C-index). The C-index is calculated as the number of concordant pairs divided by the number of comparable pairs. A C-index of 1 indicates perfect ranking, values close to 0.5 indicate random prediction, and values between 0.5 and 1 suggest some predictive ability (a value below 0.5 can be reversed by switching the response's 0 and 1 labels).

  • Prediction performance of FTT-PET and EnhanceAR-Seq ctDNA collectively as measured by area under the receiver operating characteristic (ROC) curveAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), and at progression if applicable (estimated total time 6 months)

    Prediction performance of FTT-PET and EnhanceAR-Seq ctDNA analysis collectively in predicting participant response to PARPi therapy will be assessed by the area under the ROC curve. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes model performance. A higher AUC value indicates better performance.

  • Sensitivity of EnhanceAR-Seq ctDNA in identifying mPC patients who respond to PARPi therapyAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Sensitivity is calculated as the proportion of true positives divided by the sum of true positives and false negatives. The area under the Receiver Operating Characteristic (ROC) curve will be calculated to identify the optimal cutpoint on the ROC corresponding to the maximized Youden index to evaluate sensitivity. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes model performance. A higher AUC value indicates better performance.

  • Specificity of EnhanceAR-Seq ctDNA in identifying mPC patients who respond to PARPi therapyAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Specificity is calculated as the proportion of true negatives divided by the sum of true negatives and false positives. The area under the Receiver Operating Characteristic (ROC) curve will be calculated to identify the optimal cutpoint on the ROC corresponding to the maximized Youden index to evaluate specificity. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes the performance of model. A higher AUC value indicates better performance.

  • Positive predictive value (PPV) of EnhanceAR-Seq ctDNA in identifying mPC patients who respond to PARPi therapyAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    PPV is calculated as the number of true positives divided by the sum of the number of true positives and number of false positives. The area under the Receiver Operating Characteristic (ROC) curve will be calculated to identify the optimal cutpoint on the ROC corresponding to the maximized Youden index to evaluate PPV. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes model performance. A higher AUC value indicates better performance.

  • Negative predictive value (NPV) of EnhanceAR-Seq ctDNA in identifying mPC patients who respond to PARPi therapyAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    NPV is calculated as the number of true negatives divided by the sum of the number of true negatives and number of false negatives. The area under the Receiver Operating Characteristic (ROC) curve will be calculated to identify the optimal cutpoint on the ROC corresponding to the maximized Youden index to evaluate NPV. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes model performance. A higher AUC value indicates better performance.

  • Predictive performance improvement as measured by change in concordance index of FTT-PET and EnhanceAR-seq ctDNA compared to only FTT-PET or only EnhanceAR-seq ctDNAAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Prediction performance of FTT-PET and EnhanceAR-seq ctDNA in predicting participant response to PARPi therapy will be assessed by the concordance index (C-index). The C-index is calculated as the number of concordant pairs divided by the number of comparable pairs. A C-index of 1 indicates perfect ranking, values close to 0.5 indicate random prediction, and values between 0.5 and 1 suggest some predictive ability prediction (a value below 0.5 can be reversed by switching the response's 0 and 1 labels).

  • Predictive performance improvement as measured by area under the receiver operating characteristic (ROC) curve of FTT-PET and EnhanceAR-seq ctDNA compared to only FTT-PET or only EnhanceAR-seq ctDNAAt baseline prior to PARPi therapy, post cycle 1 (cycle is an estimated 28 days), 12 weeks after start of PARPi therapy, and at progression if applicable (estimated total time 6 months)

    Prediction performance of FTT-PET and EnhanceAR-seq ctDNA in predicting participant response to PARPi therapy will be assessed by the area under the ROC curve. The ROC curve is a graphical plot that illustrates the performance of a model at various threshold settings and the area under the curve (AUC) is a single scalar value between 0 and 1 that summarizes model performance. A higher AUC value indicates better performance.