A Phase 3, Open-label Study of Ifinatamab Deruxtecan Versus Docetaxel in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC) (IDeate-Prostate01)

Trial Details

Sponsor: Merck Sharp & Dohme LLC (industry)

Phase: 3

Start date: May 13, 2025

Planned enrollment: 1440

Trial ID: NCT06925737

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More trial details at ClinicalTrials.gov

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Investigational Drug AI Analysis

Show for: Ifinatamab deruxtecan (MK-2400, DS-7300, I-DXd)

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Goal: Evaluate whether ifinatamab deruxtecan (I-DXd, MK-2400) improves overall survival and radiographic progression-free survival compared with docetaxel in metastatic castration-resistant prostate cancer (mCRPC).

Patients: Adults with mCRPC who have progressed on androgen deprivation therapy (or after bilateral orchiectomy) and after 1–2 prior androgen receptor pathway inhibitors with at least 8 weeks of exposure. Prior taxane for mCRPC is excluded; key exclusions also include history of steroid-requiring interstitial lung disease/pneumonitis and uncontrolled or significant cardiovascular disease.

Design: Phase 3, randomized, open-label, active-controlled study. Participants are randomized to I-DXd versus docetaxel. Blinded independent central review is used for radiographic endpoints. Planned enrollment is large to power dual primary endpoints of OS and rPFS.

Treatments: I-DXd: Ifinatamab deruxtecan 12 mg/kg IV every 3 weeks. I-DXd is an investigational antibody–drug conjugate targeting B7-H3 (CD276), a transmembrane immune checkpoint highly expressed across many solid tumors with limited normal-tissue expression. The ADC links a humanized anti–B7-H3 IgG1 to a topoisomerase I inhibitor payload (DXd) via a cleavable linker, enabling selective delivery and bystander effect. Early-phase and phase 2 data in pretreated small cell lung cancer showed objective response rates around 50% at the 12 mg/kg dose with median PFS approximately 5–6 months and OS near 10–12 months; key risks include gastrointestinal/hematologic toxicities and interstitial lung disease/pneumonitis observed in roughly 9–12%. Docetaxel: Standard IV chemotherapy 75 mg/m^2 every 3 weeks plus daily prednisone per label.

Outcomes: Primary outcomes: overall survival and radiographic progression-free survival per PCWG-modified RECIST 1.1 by blinded independent central review. Key secondary outcomes: time to first subsequent therapy, objective response rate and duration of response, time to pain progression, time to PSA progression, PSA response rate, time to first symptomatic skeletal-related event, and safety including adverse events and treatment discontinuations due to adverse events.

Burden on patient: Moderate. As a phase 3 study with IV therapy every 3 weeks, patients will have regular clinic visits for infusions, labs, and toxicity monitoring similar to standard chemotherapy schedules. Imaging for rPFS and PCWG-modified RECIST assessments will require periodic CT/MRI and bone scans, comparable to typical mCRPC trial follow-up intervals. There are no stated serial pharmacokinetic draws or mandatory biopsies, but monitoring for ILD/pneumonitis with symptom review and potential chest imaging increases vigilance. Overall burden is higher than an oral ARPI study due to infusion visits but comparable to standard docetaxel-based care.

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