Symbiotic-GI-03: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Adult Participants With Metastatic Colorectal Cancer

Primary Outcome Measures

1. Progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1) by Blinded Independent Central Review (BICR)
   Progression-free survival is defined as the time from the date of randomization to the date of the first documentation of objective progressive disease (PD) assessed by BICR per RECIST 1.1, or death due to any cause, whichever occurs first.
2. Overall survival (OS)
   Overall survival defined as the time from the date of randomization to the date of death due to any cause.

Secondary Outcome Measures

1. PFS per RECIST 1.1 by investigator assessment
   Progression Free Survival (PFS) is defined as the time from the date of randomization to the date of the first documentation of objective PD assessed by investigator per RECIST 1.1, or death due to any cause, whichever occurs first.
2. Objective Response Rate (ORR) by BICR
   The proportion of participants who have a confirmed CR or PR, as best overall response assessed by BICR as per RECIST 1.1.
3. Objective Response Rate (ORR) by investigator
   The proportion of participants who have a confirmed CR or PR, as best overall response assessed by investigator as per RECIST 1.1.
4. Duration of Response (DOR) by BICR
   The time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of the first documentation of PD as determined by BICR assessment per RECIST 1.1, or death due to any cause, whichever occurs first.
5. DOR by investigator
   The time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of the first documentation of PD as determined by Investigator per RECIST 1.1, or death due to any cause, whichever occurs first.
6. PFS2 (PFS after next-line therapy) by investigator
   PFS2 is defined as the time from the date of randomization to the date of second objective disease progression or death due to any cause, whichever occurs first. Second objective disease progression is PD after the start of subsequent anticancer therapy (excluding curative surgery) as assessed by the investigator.
7. Number of Participants with Treatment Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs)
8. Number of Participants With Clinical Laboratory Abnormalities
9. Pharmacokinetics (PK): Serum concentration of PF-08634404
10. Immunogenicity: Incidence of positive Anti-Drug Antibody (ADA)
    To characterize the immunogenicity of PF-08634404
11. Mean scores and Change from baseline in the global health status/quality of life (QoL) score on the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30)
    The EORTC QLQ-C30 is a questionnaire for quantitative measure of health-related quality of life pertinent to participants with a broad range of cancers who are participating in international clinical trials.
12. Mean score change from baseline in participant reported function and symptoms scales per EORTC QLQ-CR29
    The EORTC QLQ-CR29 is a supplemental colorectal cancer-specific module with measures of symptoms associated with colorectal cancer.
13. Time to definitive deterioration (TTdD) in the global health status/QoL score on the EORTC QLQ-C30
    TTdD is defined as the time from date of randomization to first onset of Patient Reported Outcome (PRO) deterioration without subsequent recovery.
14. Time to definitive deterioration (TTdD) in participant reported function and symptoms per EORTC QLQ-CR29
    TTdD is defined as the time from date of randomization to first onset of Patient Reported Outcome (PRO) deterioration without subsequent recovery.