#ASCO26 GU Oncology Spotlight 🚨
🔬 Abstract 5017 | PROTRACT
ctDNA-guided biomarker-directed therapy vs physician/patient choice in mCRPC progressing after abiraterone/prednisone
Presented by Corinne Maurice-Dror, MD
@ASCO
@OncoAlert
This is a very relevant precision-oncology question in prostate cancer:
➡️ Can ctDNA help guide whether a patient should receive docetaxel or enzalutamide after progression on abiraterone?
PROTRACT tested a simple treatment-selection strategy:
🔵 Biomarker-directed arm
• ctDNA ≥2% → docetaxel
• ctDNA <2% → enzalutamide
vs
🟠 Physician/patient choice
• docetaxel or enzalutamide, based on clinical preference
Primary endpoint: PFS
Secondary endpoints included OS, PSA50 response, PFS2, safety, and ctDNA correlatives.
🔵 Why this matters
This trial directly addresses a common real-world problem:
After abiraterone progression in mCRPC, treatment choice is often based on clinical judgment, patient preference, fitness, access, and toxicity concerns.
But biology may matter.
A higher ctDNA fraction may reflect more aggressive disease biology and could potentially support moving toward chemotherapy rather than sequential AR pathway inhibition.
🔵 Feasibility signal
The study randomized 42 patients before early termination due to slow accrual.
Importantly:
➡️ 57% of patients had discordance between physician/patient preference and ctDNA-directed assignment.
That is the key signal.
ctDNA guidance would have changed the treatment direction for more than half of patients.
🟠 Important caveat
This was underpowered and stopped early.
So PROTRACT should not be read as a definitive efficacy trial.
But it is still highly informative because it shows how often biomarker-directed treatment selection may differ from usual clinical choice.
🔵 My take
PROTRACT is important not because it settles the sequencing question, but because it frames the next one:
➡️ Can ctDNA move from prognostic biomarker to treatment-selection tool in mCRPC?
The future algorithm may not simply ask:
“ARPI again or chemotherapy?”
It may ask:
What does the tumor biology suggest this patient needs next?
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