Phase 1 · California
Phase 1 clinical trials in California
262 studies have at least one recruiting site in California. Phase 1 (and early Phase 1) trials are usually the first time a medicine is studied in people. They are typically small, closely monitored, and many are run in dedicated research units, sometimes with overnight stays.
262 recruiting studiesSource: ClinicalTrials.gov, refreshed October 26, 2026How we list studies
Studies
- RecruitingHealthy volunteersPhase 1Overnight stay mentioned
A Study to Investigate the Relative Bioavailability and Safety of Different Oral Formulations of Elecoglipron in Healthy Participants
AstraZeneca
- Location
- Glendale, CA + 1 other US site
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1Overnight stay mentioned
A Phase I Study to Investigate the Pharmacokinetics and Safety of Capivasertib in Participants With Moderate Hepatic Impairment
AstraZeneca
- Location
- Rialto, CA + 1 other US site
- Eligibility basics
- Ages 18–80
- RecruitingHealthy volunteersPhase 1Overnight stay mentioned
A Study to Learn How the Body Processes the Study Medicine PF-07328948 in People With Reduced Kidney Function
Pfizer
- Location
- Lake Forest, CA + 3 other US sites
- Eligibility basics
- Ages 18–80
- RecruitingHealthy volunteersPhase 1Overnight stay mentioned
Phase 1 Study of SBS-147 in Healthy Adults
Sparian Biosciences, Inc
- Location
- Cypress, CA
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1/Phase 2
A Study of BLB-201 RSV Vaccine in Infants and Children
Blue Lake Biotechnology Inc.
- Location
- La Mesa, CA + 13 other US sites
- Eligibility basics
- Ages 6 mo–5
- RecruitingHealthy volunteersPhase 1
A Study of V132 in Healthy Older Participants (V132-001)
Merck Sharp & Dohme LLC
- Location
- Anaheim, CA + 9 other US sites
- Eligibility basics
- Ages 50–75
- RecruitingHealthy volunteersPhase 1
A Study to Investigate Pharmacokinetics (PK), Safety, and Tolerability of VH4367310 in Healthy Adult Participants
ViiV Healthcare
- Location
- Glendale, CA + 1 other US site
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1
Study of S-892216 Long-acting Injectable (LAI) in Healthy Adult Participants
Shionogi
- Location
- Cypress, CA
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1
A Study of LY4006896 in Healthy Participants and Participants With Parkinson's Disease
Eli Lilly and Company
- Location
- Los Alamitos, CA + 7 other US sites
- Eligibility basics
- Ages 30–85
- RecruitingHealthy volunteersPhase 1/Phase 2
Phase 1/2 Study of Respiratory Syncytial Virus and Human Metapneumovirus (RSV+HMPV) Vaccine Candidate in Adults 60 Years of Age and Older
Sanofi
- Location
- Huntington Beach, CA + 49 other US sites
- Eligibility basics
- Ages 60+
- RecruitingHealthy volunteersPhase 1
A Study to Test How BI 1291583 is Taken up in the Blood of People With and Without Liver Problems
Boehringer Ingelheim
- Location
- Rialto, CA
- Eligibility basics
- Ages 18–80
- RecruitingHealthy volunteersPhase 1
A Study to Investigate Safety, Tolerability, and Pharmacokinetics of AZD3974 in Healthy Participants
AstraZeneca
- Location
- Glendale, CA + 1 other US site
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1
A Study to Investigate Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of AZD1043 in Healthy Adult Participants Living With Overweight and/or Obesity.
AstraZeneca
- Location
- Glendale, CA + 1 other US site
- Eligibility basics
- Ages 18–65
- RecruitingHealthy volunteersPhase 1
First-in-Human Trial to Assess REGN20423 in Healthy Adult Participants and Adult Participants With Atopic Dermatitis
Regeneron Pharmaceuticals
- Location
- West Hills, CA + 5 other US sites
- Eligibility basics
- Ages 18–65
- RecruitingHealthy volunteersPhase 1
A Clinical Study of Novel Pneumococcal Vaccine V118C in Children (V118C-002)
Merck Sharp & Dohme LLC
- Location
- Madera, CA + 14 other US sites
- Eligibility basics
- Ages 2 mo–1
- RecruitingHealthy volunteersPhase 1
A Study to Evaluate Safety, Tolerability and Pharmacokinetics of Orally Administered TIX100 in Healthy Subjects
TIXiMED, Inc.
- Location
- Chula Vista, CA
- Eligibility basics
- Ages 18–70
- RecruitingHealthy volunteersPhase 1/Phase 2
Study of XmAb942 in Healthy Participants and Participants With Ulcerative Colitis
Xencor, Inc.
- Location
- Palo Alto, CA + 27 other US sites
- Eligibility basics
- Ages 18–75
- RecruitingHealthy volunteersPhase 1
A Study of BBT001 in Healthy Volunteers (HVs) and in Adult Patients With Atopic Dermatitis (AD)
Bambusa Therapeutics
- Location
- Irvine, CA + 2 other US sites
- Eligibility basics
- Ages 18–72
- RecruitingHealthy volunteersPhase 1
A Study to Investigate the Safety and Pharmacokinetics of Single- and Multiple-ascending Doses of AZD4916 in Healthy Volunteers
AstraZeneca
- Location
- Glendale, CA
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1
A Study to Assess Safety, Tolerability, and How Single and Multiple Injections or Infusions of ABBV-313 Affects the Body of Adult Participants
AbbVie
- Location
- Anaheim, CA + 1 other US site
- Eligibility basics
- Ages 18–55
- RecruitingHealthy volunteersPhase 1
Safety and Drug Concentrations of REGN20934 in Adults With Overweight or Obesity
Regeneron Pharmaceuticals
- Location
- Glendale, CA
- Eligibility basics
- Ages 18–65
- RecruitingHealthy volunteersPhase 1
A Study to Evaluate the Drug Levels, Absolute Bioavailability, Safety, Tolerability, and Immunogenicity of Single-Dose of BMS-986446 in Healthy Adults After Single-dose Administration, and Participants With Early…
Bristol-Myers Squibb
- Location
- Anaheim, CA
- Eligibility basics
- Ages 18–80
- RecruitingHealthy volunteersPhase 1/Phase 2
Study to Assess Safety and Immunogenicity of an Egg-based H5N8 Influenza Vaccine at Multiple Dose Levels Adjuvanted With Matrix-M in Healthy Participants 18 Years of Age and Above.
Sanofi
- Location
- Rolling Hills Estates, CA + 15 other US sites
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteersPhase 1/Phase 2
First-in-human Study of the Safety, Tolerability, Pharmacokinetics, and Food Effect of ACCG-2671
Aconcagua Bio, Inc. a wholly owned subsidiary of Structure Therapeutics
- Location
- Lake Forest, CA + 2 other US sites
- Eligibility basics
- Ages 25–75
Who these studies look for
Phase 1 studies often have narrow eligibility: specific age and weight ranges, no recent participation in another study, no nicotine, and limits on medications. Some Phase 1 studies recruit patients rather than healthy volunteers, so check each listing.
Matching a page like this one never means you qualify. Each research team decides eligibility at screening.
Questions
Are Phase 1 trials riskier?
Every study carries risk. Phase 1 studies involve less human data about the product, which is why they are closely monitored. The informed consent document explains the known risks; read it carefully and ask questions before signing.
Why do some Phase 1 studies include overnight stays?
Staying in the unit lets staff dose on a precise schedule and collect samples around the clock. Where a record mentions an inpatient stay we flag it on the listing.