California's clinical trial pipeline slowed down in April. The state opened 61 new trials, roughly half the 117 opened in March and about a quarter of February's 226. At the same time, 514 trials are set to close within the next 90 days, the heaviest closing wave of any month since November.

These two numbers matter together. Fewer new launches mean this is not a month when fresh opportunities appear for every condition. The large closing wave means many trials already enrolling are approaching their finish line, with seats disappearing.

California still has 5,466 trials actively recruiting, 782 of them open to healthy volunteers, and active studies running in 303 cities. Anyone in the state looking at paid clinical trials in California can filter the directory by city and by what each study evaluates.

Where New Trials Opened

San Francisco led the state this month with 16 new launches. Los Angeles followed with 7, San Diego with 6. Palo Alto and Glendale each opened 4. Encinitas and La Jolla each added 3.

The broader map follows the same cities. Across all 5,466 active trials, Los Angeles carries 1,866, San Francisco 1,178, and San Diego 696. Palo Alto, Sacramento, Duarte, La Jolla, and Orange each sit between 500 and 600. For readers in any of those metros, the chance of finding something locally is high.

A few of April's new launches stand out. Kaiser Permanente opened NCT07573205, a Phase 3 adherence study for dyslipidemia therapy targeting 22,000 participants, one of the largest new-launch enrollment numbers in the country this month. Novartis began NCT07517263, the open-label extension of its pelacarsen program (TQJ230) with 5,700 participants, focused on long-term safety in people who completed the earlier blinded phase.

Stanford opened NCT07522773, a 3,900-participant behavioral study that uses patient storytelling to improve colorectal cancer screening uptake. Ozmo Health started NCT07536780 (AUDIBLE), an ultrasound-imaging trial for breast cancer evaluation, enrolling 888 women. Ocular Therapeutix launched NCT07518132, a retinal-disease implant study with 868 participants. Cepheid's NCT07516471 evaluates a rapid fever diagnostic with 2,500 subjects. Nuclera began NCT07514414, a 1,800-subject observational study for a bladder cancer urine test.

Who Is Running the Research

California's sponsor landscape is heavily academic. UCSF leads with 237 active trials, Stanford is right behind at 236. City of Hope Medical Center (146), UCLA (145), UC San Diego (138), and UC Davis (110) round out the academic top. The National Cancer Institute has 108 trials running across the state.

On the industry side, AstraZeneca leads with 106. Eli Lilly follows with 74, then AbbVie and Merck Sharp & Dohme at 67 each. The University of Southern California sits at 88.

Broken down by intervention type, the active portfolio is 2,882 drug trials, 737 device trials, 592 procedure studies, 549 biological, 494 behavioral, 171 radiation, and 139 diagnostic test trials, with another 959 falling under other.

Who Can Participate

Across all 5,466 active trials, 4,545 include older adults and 1,160 accept children as part of their eligible pool, with another 321 dedicated to children only. 281 are adults-only. 284 are female-only, 214 male-only. And 782 trials, roughly 14 percent of the total, are actively recruiting healthy volunteers.

The number of healthy volunteers tends to be overlooked. These studies do not require a specific diagnosis, and they're often the most accessible entry into paid research. California has them at scale. Among the trials closing soon, 8 are healthy-volunteer studies, one of the highest-closing-soon categories on the list.

What's Closing

The 514 trials closing in the next 90 days span a wide range of conditions. The biggest clusters by count: 8 healthy-volunteer studies, 7 colorectal cancer, 7 breast cancer, 6 cholangiocarcinoma, 6 anxiety, 6 acute myeloid leukemia. Gastric cancer, amyotrophic lateral sclerosis, Parkinson's disease, and mild cognitive impairment each have 5 trials reaching their close dates.

For anyone who matches the inclusion criteria for one of these conditions, the window is narrow. Enrollment often closes before the official close date once a trial hits its recruitment target, so "closing in 90 days" can mean much sooner in practice.

Looking Ahead

The six-month trend has a clear shape. November and December 2025 were the busiest months for new launches (122 and 260 trials, respectively), and closings stayed modest through the winter. Since January, launches have trended down while closings have started, ending in April's 514-trial wave.

None of this is unusual. Academic calendars, FDA decision timing, and industry funding cycles all shape when a sponsor opens a new trial or wraps up an existing one. Whether May returns to mid-range activity depends on how those factors line up.

For anyone who's been considering participation, the current month has its own logic. With fewer new trials launching, the ones still enrolling are getting more visibility, and the closing wave is thinning out the pool faster than any month so far this year. Hipa.ai publishes a refreshed California report each month with updated splits by sponsor, city, and condition.