Bonnie Miller Rubin / Chicago Tribune

CHICAGO — For most people, attending a relative’s wedding is a happy occasion. But for one suburban Chicago couple, seeing their son socialize and dance qualified as a once-in-a-lifetime thrill.

“Ethan was just so appropriate ... so engaged in life,” said Rebecca Fishman of Highland Park, reflecting on the spring event. “For one glorious moment, we got to be this normal family ... and I just can’t let that slip away.”

Ethan Fishman, 20, has Fragile X syndrome, a genetic condition closely related to autism. His mother credited his newfound social skills to arbaclofen, an experimental drug he was taking in a clinical trial.

But the study was terminated in May because it failed to reach its goals and resources were limited, according to a statement from Seaside Therapeutics, the company that created the drug.

“It’s just been devastating,” said Rebecca Fishman, who was attending her 11-year-old child’s school concert when the news about ending the study popped up in a text message. “I had to get out of there. ... It felt like a death.”

The Fishmans’ experience sheds light on the emotional roller coaster of all clinical trials, which combine vulnerable and often desperate patients with untested drugs and market forces. Despite all the consent forms and cautionary language, the subjects sometimes perceive the process as a cure, rather than an experiment.

It also illuminates the long odds of bringing new drugs to market.

Three Illinois families whose children participated in the trial and took arbaclofen told the Chicago Tribune they believe the drug reduced their children’s anxiety or increased communication. They viewed the drug as the key to unlocking the enigma of Fragile X, which has no cure and affects 1 in 100,000 Americans, with symptoms ranging from mild aggression to severe cognitive impairment.

While the drug showed significant benefits in some areas in the 300-patient trial, researchers said, it failed to beat the placebo on the main goal of the study: social withdrawal.

The drug is unavailable anywhere in the world, leaving the families frustrated and feeling abandoned. Following the announcement, advocates started online petitions, reached out to potential investors and even appealed to the White House, all to no avail.

“I got so much out of those 31⁄2 years,” sighed Holly Usrey-Roos, referring to her son’s time in the study. His vocabulary exploded, enabling the 14-year-old to use a complete sentence rather than a single word when he wanted an object. One of those sentences allowed Usrey-Roos to hear Parker say “I love you” for the first time.

Melissa Zolecki of Plainfield said she also observed dramatic strides forward, including being able to take her 12-year-old son, Matt, for his regular blood draws without him physically resisting.

“It’s just so frustrating to know that there’s help out there and not be able to fix it,” said Zolecki, whose son started taking arbaclofen in 2010 and finished his last dose in mid-June.

Ethan, Parker and Matt are just a few of the 40 patients followed by Dr. Elizabeth Berry-Kravis, a key investigator for the trial of the drug, also known as STX209.

After four years, arbaclofen was in the home stretch of new drug development that could lead to Food and Drug Administration approval for marketing — to confirm effectiveness, monitor side effects and collect data. It also required meeting a clearly stated and specific goal: in this case, arbaclofen’s effect on social withdrawal in patients ages 12 to 25.

During the first three months, neither Berry-Kravis nor the volunteers knew who was on the drug or the placebo. Later, all participants had the option of going on arbaclofen.

The drug cleared early safety hurdles and researchers were focused primarily on efficacy, said the pediatric neurologist. Among her participants taking the drug, about one-third had little or no improvement from their previous behaviors, one-third showed some benefits and for the remaining 30-40 percent arbaclofen “could be life-changing,” she said.

Measuring the drug’s effectiveness can be difficult because children and young adults develop at different rates, and some will mature and show behavioral and cognitive improvements without the help of drugs at all. Moreover, the gains were not always the particular behavior that Seaside was looking for, so it still counts as a failed study.

When the statistics were compiled, arbaclofen didn’t succeed strongly enough and scientific rigor trumped anecdote.