A Clinical Study of Ifinatamab Deruxtecan (I-DXd) in People With Metastatic Prostate Cancer (MK-2400-001)

Overall Survival (OS)

Timeframe: Up to approximately 36 months

OS is defined as the time from randomization to death due to any cause.

Radiographic Progression Free Survival (rPFS)

Timeframe: Up to approximately 36 months

rPFS is defined as the time from randomization to the first documented disease progression per prostate cancer working group (PCWG)-modifed Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 by blinded independent central review (BICR) or death due to any cause, whichever occurs first.

Time to First Subsequent Therapy (TFST)

Timeframe: Up to approximately 36 months

TFST is defined as the time from randomization to initiation of the first subsequent anticancer therapy or death, whichever occurs first.

Objective Response Rate (ORR)

Timeframe: Up to approximately 36 months

The ORR is defined as a confirmed complete response (CR) or partial response (PR) per PCWG-modified RECIST 1.1 as assessed by BICR.

Duration of Response (DOR)

Timeframe: Up to approximately 36 months

For participants who demonstrate confirmed CR or PR, DOR is defined as the time from the first documented evidence of CR or PR until disease progression per PCWG-modified RECIST 1.1 as assessed by BICR or death due to any cause, whichever occurs first.

Time to Pain Progression (TTPP)

Timeframe: Up to approximately 36 months

TTPP is defined as the time from randomization to pain progression based on the brief pain inventory-short form (BPI-SF) Item 3 "worst pain in 24 hours" and opiate analgesic use (AQA score).

Time to Prostate-specific Antigen (PSA) Progression

Timeframe: Up to approximately 36 months

Time to PSA progression is defined as the time from randomization to PSA progression. The PSA progression date is defined as the first date that 1) ≥25% increase and ≥2 ng/mL above the nadir which is confirmed by a second value≥3 weeks later if there is PSA decline from baseline, 2) ≥25% increase and ≥2 ng/mL increase from baseline beyond 12 weeks if there is no PSA decline from baseline.

PSA Response Rate

Timeframe: Up to approximately 36 months

PSA response rate is defined as the proportion of participants in the analysis population who have a PSA reduction of ≥50% from baseline with a consecutive confirmation assessment at least 3 weeks later per PCWG criteria.

Time to First Symptomatic Skeletal-Related Event (SSRE)

Timeframe: Up to approximately 36 months

Time to first SSRE is defined as the time from randomization to the first occurrence of any of the following symptomatic skeletal-related events: 1. use of EBRT to prevent or relieve skeletal symptoms, 2. new symptomatic pathologic bone fracture (vertebral or non-vertebral), 3. spinal cord compression, 4. a tumor-related orthopedic surgical intervention.

Number of Participants Who Experienced at Least One Adverse Event (AE)

Timeframe: Up to approximately 36 months

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention.

Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE)

Timeframe: Up to approximately 36 months

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention.