Clinical Trials in California, 2026
Every industry-sponsored study on the ClinicalTrials.gov registry that lists a US site and is open, about to open, active-but-closed, or enrolling by invitation. This deliberately excludes academic and other non-industry sponsors — the full US registry across all sponsors runs to over 22,000 recruiting studies alone.
About this register
This register is built from ClinicalTrials.gov, the trial registry run by the U.S. National Library of Medicine. It includes every industry-sponsored study on the registry that lists at least one investigative site in the US and is recruiting, not yet recruiting, active but no longer recruiting, or enrolling by invitation: 9,159 studies in total at the last sync on 25 Oct 2026, 03:16 UTC. Academic and other non-industry sponsors are out of scope by design. The full list can be downloaded as CSV or queried as JSON through the register API.
This page shows the 28 of those studies with a site in California that also match the filters currently applied.
How many clinical trials are recruiting in California?
14 of the 28 studies on this page are recruiting new participants as of the 25 Oct 2026, 03:16 UTC sync. A further 2 have not yet opened recruitment, 7 are active but closed to new participants, and 5 are enrolling by invitation only. Eligibility for any study is decided by its study team.
Summary by phase
| Phase | Studies | Recruiting | Share |
|---|---|---|---|
| Phase 3 | 13 | 7 | 46.4% |
| Phase 2 | 7 | 5 | 25% |
| Observational | 4 | 0 | 14.3% |
| Phase 4 | 2 | 2 | 7.1% |
| Not applicable | 1 | 0 | 3.6% |
| Phase 1/2 | 1 | 0 | 3.6% |
Most active sponsors
| Lead sponsor | Studies | Recruiting |
|---|---|---|
| Neurocrine Biosciences | 6 | 6 |
| Xenon Pharmaceuticals Inc. | 3 | 0 |
| Cybin IRL Limited | 2 | 0 |
| Definium Therapeutics US, Inc. | 2 | 1 |
| Syndeio Biosciences, Inc | 2 | 2 |
| AbbVie | 1 | 1 |
| Alto Neuroscience | 1 | 1 |
| Autobahn Therapeutics, Inc. | 1 | 1 |
| Axsome Therapeutics, Inc. | 1 | 1 |
| BioLite, Inc. | 1 | 0 |