When British pharmaceutical giant GlaxoSmithKline announced in October 2012 that it planned to make detailed data from its clinical trials widely available to researchers outside its own walls, the scientific community was stunned. For a company that spends $6.5 billion a year on research and development, it was a sharp turn away from the system of data secrecy that had made it one of the world’s largest drug companies, with 2013 sales of $43.6 billion.

The announcement came a few months after the company pled guilty to misdemeanor charges in the U.S. that it had marketed drugs for unapproved uses, based on improperly reported clinical trial data, and failed to report safety data on another drug later shown to raise the risk of heart attacks. Given the timing, many wondered if GSK’s move was more about rehabilitating its image than embracing data transparency.

GlaxoSmithKline’s efforts since could turn those skeptics into believers. In May 2013, the company began posting its own data online. Then it invited others to join ClinicalStudyDataRequest.com, where GSK and six other drugmakers have already uploaded data from nearly 900 clinical trials, and more than a dozen research projects are under way.

Trial transparency is appealing thanks to a growing sense that it could make drug development more efficient, saving the industry billions while also getting breakthrough therapies to patients more quickly.

In the United States, health reform has increased the pressure on insurers and government payers such as Medicare to control costs, in part by paying for treatments that are targeted to the patients most likely to benefit from them. If researchers could see the mistakes made by rivals in the past—compounds that were too toxic or not potent enough—they could design better trials. Those could, in turn, get new drugs to market faster—tempting to an industry that spends $150 billion a year on R&D globally but still fails to find enough new hits to replace its aging blockbusters.

Balancing secrecy and privacy concerns with the potential benefits of data sharing required new technological tools and an unprecedented level of coöperation among companies that typically consider themselves fierce rivals.

For GSK, the project started several years before the 2012 announcement as an internal platform that allowed researchers to scrutinize data from past clinical trials. Moving that data outside the company required scouring away any details that might compromise patient privacy.

To preserve the integrity of the data—to prevent users from e-mailing it to people who weren’t authorized to see it, or surreptitiously altering it in any way—GSK hired the software analytics firm SAS to build a sort of data castle and moat, says Matt Gross, SAS’s director of the health and life sciences global practice. SAS built a secure environment in which approved researchers could access a suite of tools to allow them to crunch the numbers.

The site allows researchers, for the first time, to obtain data on the same topic from many companies simultaneously. “We can combine all of the evidence from many studies to get one overall result,” says Sarah Nolan, a research assistant in medical statistics at the University of Liverpool. Nolan is working on a three-year research project designed to determine the clinical utility and cost-effectiveness of various epilepsy treatments. She uses ClinicalStudyDataRequest.com to look at factors such as whether the age of the patients affects their responses to drugs and what prompts some patients to drop out of trials—details that speak to the tolerability of drugs but are rarely reported in standard published trials.

Transparency is spreading. France’s Sanofi, in addition to putting its trial results on ClinicalStudyDataRequest.com, has posted three prostate cancer trials on Project Data Sphere, a pharma-supported site aimed at using data sharing to speed up the development of new cancer cures. Companies such as Johnson & Johnson and Pfizer are erecting their own data-sharing sites.

As for GSK, widely credited with starting the transparency trend, it continues to build upon the platform it invented. The company has posted 450 studies online, says Perry Nisen, GSK’s vice president for science and innovation. And after having initially promised to release clinical trials from 2007 forward, it is now disclosing research dating back to 2000.

This new age of openness could lead to further changes. Philip Huang, vice president of strategic planning and operations for Sanofi, says the next step will be to unify the procedures followed in clinical trials. In September 2012, Sanofi, GSK, and Roche helped found TransCelerate BioPharma, a nonprofit that creates standards for collecting and reporting clinical-trial data. “It will essentially give investigators a single playbook, if you will, for how to do clinical research,” Huang says.