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PG4

Phase 3

Pneumococcal Disease | Monoclonal antibody | Infectious Disease |Pfizer, Inc.|Last Updated: Sep 8, 2026

Target and mechanism

ModalityMonoclonal antibody

Also known as PG4 vaccine in Buffer 1 with low dose PA-001, PG4 vaccine in Buffer 2, PG4 Multivalent Vaccine

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindACTIVE_CONTROLLEDDMC
Total Trials6
Total Enrollment12,330

FDA Designations

No designations recorded

Clinical trial landscape

PG4 · 7 trials · 2 indications

Phase 3 4Phase 2 2Phase 1 1
NCT07794748A Study to Assess the Safety, Tolerability, and Immunogenicity of 3 Lots of a Multivalent Pneumococcal Conjugate Vaccine Administered to AdultsPneumococcal Disease
NOT YET_RECRUITING4,670 Analytics
NCT07660198Study to Learn About Safety, Tolerability, and Immune Response of a Catch-up Pneumococcal Vaccine in Children and AdolescentsPneumococcal Disease
RECRUITING1,200 Analytics
NCT07629440A Study to Learn About How a New Pneumococcal Vaccine Works in Infants.Pneumococcal Disease
RECRUITING3,230 Analytics
NCT07573462A Study to Learn About the Safety of an Expanded Pneumococcal Vaccine in Healthy InfantsPneumococcal Disease
RECRUITING2,400 Analytics
PHASE3NOT YET_RECRUITING
A Study to Assess the Safety, Tolerability, and Immunogenicity of 3 Lots of a Multivalent Pneumococcal Conjugate Vaccine Administered to Adults
Pneumococcal DiseaseUnlock trial analytics
PHASE3RECRUITING
Study to Learn About Safety, Tolerability, and Immune Response of a Catch-up Pneumococcal Vaccine in Children and Adolescents
Pneumococcal DiseaseUnlock trial analytics
PHASE3RECRUITING
A Study to Learn About How a New Pneumococcal Vaccine Works in Infants.
Pneumococcal DiseaseUnlock trial analytics
PHASE3RECRUITING
A Study to Learn About the Safety of an Expanded Pneumococcal Vaccine in Healthy Infants
Pneumococcal DiseaseUnlock trial analytics

Study Endpoints

Primary Endpoints

Percentage of Participants with Prespecified Local Reactions Within 7 Days After Vaccination
Within 7 days after Vaccination

Prompted local reactions after each dose

Percentage of Participants reporting Prespecified Systemic Events Within 7 Days after Vaccination
Within 7 days after Vaccination

Prompted systemic events after each dose

Percentage of Participants with Adverse Events (AEs)
From Vaccination to 1 month after Vaccination

AEs occurring from Dose 1 to 1 month after the vaccination

Percentage of Participants with Serious Adverse Events (SAEs)
From Vaccination to 6 months after Vaccination

SAEs occurring from Dose 1 to 6 months after the vaccination

OPA geometric mean ratios (GMR) between each pair of PG4 vaccine lots
1 month after Vaccination

OPA GMRs between each pair of PG4 vaccine lots at 1 month after vaccination

Percentage of Participants With Local Reactions Within 7 Days After Vaccination
Within 7 days after Vaccination
Percentage of Participants With Systemic Events Within 7 Days after Vaccination
Within 7 days after Vaccination
GMCs of serotype-specific IgG concentrations
1 month after vaccination
GMTs of serotype-specific OPA titers
1 month after vaccination
Percentage of participants reporting local reactions within 7 days after each dose
Day 7

Prompted local reactions after each dose

Percentage of participants reporting systemic events within 7 days after each dose
Day 7

Prompted systemic events after each dose

Percentage of participants reporting adverse events (AEs) from Dose 1 to 1 month after Dose 3
Dose 1 to 1 month after Dose 3

AEs occurring from Dose 1 to 1 month after Dose 3

Percentage of participants reporting AEs from Dose 4 to 1 month after Dose 4
Dose 4 to 1 month after Dose 4

AEs occurring from Dose 4 to 1 month after Dose 4

Percentage of participants reporting serious adverse events (SAEs)
Dose 1 to 6 months after Dose 4

SAEs occurring from Dose 1 to 6 months after Dose 4

Differences in percentages of participants with predefined pneumococcal specific immunoglobulin G (IgG) concentrations 1 month after Dose 3
1 month after Dose 3

Differences in pneumococcal immunoglobulin G (IgG) concentrations 1 month after Dose 3

Pneumococcal IgG geometric mean concentrations (GMCs) 1 month after Dose 4
1 month after Dose 4

Pneumococcal IgG GMCs 1 month after Dose 4

Percentage of participants reporting prespecified local reactions within 7 days after each dose
7 days after each dose

Prespecified local reactions (redness, swelling, and pain at the injection site) after each dose

Percentage of participants reporting prespecified systemic events within 7 days after each dose
7 days after each dose

Prespecified systemic events (fever, decreased appetite, drowsiness/increased sleep, and irritability) after each dose

Percentage of participants reporting Adverse Events (AEs) within 1 month after the last assigned vaccination
From signing of ICD to 1 month after last assigned vaccination

Adverse events occurring within 1 month after the last assigned vaccination

Percentage of participants reporting Serious Adverse Events (SAEs) within 6 months after vaccination
From signing of ICD to 6 months after last assigned vaccination

SAEs occurring from Dose 1 through 6 months after the last assigned vaccination

Percentage of participants reporting adverse events (AEs)
Dose 1 to 1 month after Dose 3

AEs occurring from Dose 1 to 1 month after Dose 2

Percentage of participants reporting AEs
Dose 4 to 1 month after Dose 4

AEs occurring from Dose 4 to 1 month after Dose 4

Percentage of participants reporting prespecified local reactions after each dose.
Within 7 days after each study intervention.

Prespecified local reactions (redness, swelling, and pain at the injection site) occurring within 7 days of each dose administered in the study.

Percentage of participants reporting prespecified systemic reactions after each dose.
Within 7 days after each study intervention.

Prespecified systemic reactions (fever, vomiting, diarrhea, headache, fatigue, muscle pain, and joint pain) occurring within 7 days of each dose administered in the study.

Percentage of participants reporting adverse events.
From signing of the ICD to 1 month after last study intervention.

Adverse Events (AEs) occurring from Dose 1 through 1 month after the last vaccination

Percentage of participants reporting serious adverse events.
From signing of the ICD to 6 months after the last study intervention.

Serious Adverse Events (SAEs) occurring from Dose 1 through 6 months after the last vaccination.

Percentage of participants with abnormal hematology and chemistry laboratory values.
Within 2 weeks after each study intervention.

Any abnormal hematology or chemistry laboratory values as compared to baseline within 2 weeks after each study intervention.

Secondary Endpoints

OPA Serotype-specific geometric mean titers (GMT) for PG4 vaccine serotypes
1 month after Vaccination
OPA geometric mean fold rise (GMFR) for PG4 vaccine serotypes
From before vaccination to 1 month after vaccination
Percentages of participants with a ≥4-fold rise in opsonophagocytic activity (OPA) titers
From Vaccination to 6 months after Vaccination
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Study Design & Arms

AllocationRANDOMIZED
MaskingTRIPLE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
PG4 Vaccine Lot 1EXPERIMENTALMultivalent Pneumococcal Vaccine
PG4 Vaccine Lot 2EXPERIMENTALMultivalent Pneumococcal Vaccine
PG4 Vaccine Lot 3EXPERIMENTALMultivalent Pneumococcal Vaccine
20 Valent Pneumococcal Conjugate Vaccine (20vPnC)ACTIVE_COMPARATOR20 Valent Pneumococcal Conjugate Vaccine
PG4 (intramuscular)EXPERIMENTALMultivalent Pneumococcal vaccine
20-valent pneumococcal conjugate vaccine (20vPnC) (intramuscular)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 1 PG4 (intramuscular)EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 1 20-valent pneumococcal conjugate vaccine (20vPnC) (intramuscular)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 2 PG4 (intramuscular)EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 2 20-valent pneumococcal conjugate vaccine (20vPnC) (intramuscular)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 3 PG4 (intramuscular)EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 3 PG4 (subcutaneous)EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 3 20-valent pneumococcal conjugate vaccine (20vPnC) (intramuscular)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
PG4 1-Dose GroupEXPERIMENTALParticipants to receive a single injection of Multivalent Pneumococcal Vaccine
PG4 2-Dose GroupEXPERIMENTALParticipants to receive two injections of Multivalent Pneumococcal Vaccine
20-valent pneumococcal conjugate vaccine (20vPnC)ACTIVE_COMPARATORParticipants to receive a single injection of 20-valent pneumococcal conjugate vaccine (20vPnC).
Group 1 PG4EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 1 20-valent pneumococcal conjugate vaccine (20vPnC)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 2 PG4EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 2 20-valent pneumococcal conjugate vaccine (20vPnC)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 3 PG4EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 3 20-valent pneumococcal conjugate vaccine (20vPnC)ACTIVE_COMPARATOR20-valent pneumococcal conjugate vaccine (20vPnC)
Group 4 PG4EXPERIMENTALMultivalent Pneumococcal Vaccine
Group 4 15-valent pneumococcal conjugate vaccine (PCV15)ACTIVE_COMPARATOR15-valent pneumococcal conjugate vaccine (PCV15)
PG4 vaccine with low dose adjuvant PA-001; dose schedule 1EXPERIMENTAL -
PG4 vaccine with low dose adjuvant PA-001; dose schedule 2EXPERIMENTAL -
PG4 vaccine with low dose adjuvant PA-002; dose schedule 1EXPERIMENTAL -
PG4 vaccine with low dose adjuvant PA-002; dose schedule 2EXPERIMENTAL -
PG4 vaccine with high dose adjuvant PA-001; dose schedule 1EXPERIMENTAL -
PG4 vaccine with high dose adjuvant PA-001; dose schedule 2EXPERIMENTAL -
PG4 vaccine with high dose adjuvant PA-002; dose schedule 1EXPERIMENTAL -
PG4 vaccine with high dose adjuvant PA-002; dose schedule 2EXPERIMENTAL -
PG4 vaccine; dose schedule 1ACTIVE_COMPARATOR -
PG4 vaccine; dose schedule 2ACTIVE_COMPARATOR -
20vPnC; dose schedule 1ACTIVE_COMPARATOR -
20vPnC; dose schedule 2ACTIVE_COMPARATOR -

Interventions

NameTypeDescription
PG4 Multivalent VaccineBIOLOGICALMultivalent Pneumococcal Vaccine
20 Valent Pneumococcal Conjugate Vaccine (20vPnC)BIOLOGICAL20 Valent Pneumococcal Conjugate Vaccine
PG4BIOLOGICALMultivalent Pneumococcal Vaccine
20-valent pneumococcal conjugate vaccine (20vPnC)BIOLOGICAL20-valent pneumococcal conjugate vaccine (20vPnC)
15-valent pneumococcal conjugate vaccine (PCV15)BIOLOGICAL15-valent pneumococcal conjugate vaccine
PG4 vaccine in Buffer 1 with low dose PA-001BIOLOGICALMultivalent pneumococcal conjugate vaccine
PG4 in Buffer 1 with low dose PA-002BIOLOGICALMultivalent pneumococcal conjugate vaccine
PG4 in Buffer 1 with high dose PA-001BIOLOGICALMultivalent pneumococcal conjugate vaccine
PG4 vaccine in Buffer 1 with high dose PA-002BIOLOGICALMultivalent pneumococcal conjugate vaccine
PG4 vaccine in Buffer 2BIOLOGICALMultivalent pneumococcal conjugate vaccine
20-valent pneumococcal conjugate vaccineBIOLOGICAL(20vPnC)
Saline injectionBIOLOGICALPlacebo
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Eligibility Criteria

Age Range18 Years to 49 Years
SexALL
Healthy VolunteersYes
Study Sites25

Inclusion Criteria: Adults 18 through 49 years of age, who have no history of receiving a pneumococcal vaccine after 5 years of age. Exclusion Criteria: Individuals with a history of severe allergic reactions to a vaccine or its components, serious chronic medical disorders, significant psychiatr...

Countries:United StatesPuerto RicoJapanAustraliaCanada
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Recent Changes (Last 90 Days)

LOWSep 8, 2026NCT07629440lastUpdatePostDate: changed
LOWSep 8, 2026NCT07629440lastUpdatePostDate: changed
LOWSep 3, 2026NCT06524414lastUpdatePostDate: changed
LOWSep 3, 2026NCT06524414lastUpdatePostDate: changed
LOWAug 31, 2026NCT07794748NEW_TRIAL: changed
LOWAug 31, 2026NCT07660198lastUpdatePostDate: changed
LOWAug 31, 2026NCT07794748NEW_TRIAL: changed
LOWAug 31, 2026NCT07660198lastUpdatePostDate: changed
LOWAug 11, 2026NCT07573462lastUpdatePostDate: changed
LOWAug 11, 2026NCT07573462lastUpdatePostDate: changed
LOWAug 11, 2026NCT07573462lastUpdatePostDate: changed
LOWJul 9, 2026NCT07660198lastUpdatePostDate: changed
LOWJul 9, 2026NCT07629440lastUpdatePostDate: changed
LOWJul 9, 2026NCT07573462lastUpdatePostDate: changed
LOWJul 9, 2026NCT06524414lastUpdatePostDate: changed
LOWJul 9, 2026NCT07660198lastUpdatePostDate: changed
LOWJul 9, 2026NCT07629440lastUpdatePostDate: changed
LOWJul 9, 2026NCT07573462lastUpdatePostDate: changed
LOWJul 9, 2026NCT06524414lastUpdatePostDate: changed
LOWJun 24, 2026NCT07660198primaryCompletionDate: changed

Frequently asked questions about PG4

What is PG4 used for?

PG4 is an investigational monoclonal antibody being developed by Pfizer for the prevention of pneumococcal disease. It is currently in Phase 3 clinical trials, with studies evaluating its use in infants and children to protect against infections caused by Streptococcus pneumoniae.

Who is developing PG4?

PG4 is being developed by Pfizer, Inc., a global biopharmaceutical company listed on the New York Stock Exchange under the ticker symbol PFE. The company is conducting multiple clinical trials to evaluate the safety and efficacy of this investigational monoclonal antibody for pneumococcal disease.

What phase is PG4 in?

PG4 is currently in Phase 3 clinical development. Pfizer has completed a Phase 2 trial and is now conducting two Phase 3 studies in infants, with one additional Phase 3 trial actively recruiting participants. The drug remains investigational and has not been approved by regulatory authorities.

What clinical trials is PG4 in?

PG4 is being studied in several clinical trials, including NCT07573462, a Phase 3 study in healthy infants with 2,400 participants, and NCT07629440, a Phase 3 study in infants with 3,230 participants. Both are actively recruiting in the United States and other countries.

How does PG4 work?

PG4 is a monoclonal antibody designed to target pneumococcal bacteria, which cause pneumococcal disease. By binding to specific components of the bacteria, it may help the immune system neutralize the pathogen and prevent infection. The exact molecular target has not been disclosed in available information.

Is PG4 the same as a pneumococcal vaccine?

PG4 is not a vaccine but a monoclonal antibody. While vaccines stimulate the immune system to produce antibodies, PG4 is a laboratory-made antibody that provides passive immunity. It is being studied as a potential preventive treatment for pneumococcal disease in infants and children.