The actor and his wife co-hosted an event to commemorate the 25th anniversary of Project A.L.S., which was started by Jennifer Estess, a late friend who died of the disease.

Ben Stiller and wife Christine Taylor made a rare public appearance with their 18-year-old son Quinlin Dempsey on Thursday for a family cause.

Stiller, 57, and Taylor, 52, cohosted a banquet to commemorate Project ALS’s 25th anniversary, which was created by close friend Jennifer Estess, who died of the disease at the age of 40.

“I think we were all taken aback by what happened to her. And it’s such a terrible disease. Stiller told PEOPLE that Estess “was a really good friend of mine in the theater community” and that “it’s one of those diseases where there is no real cure for it.”

Stiller told PEOPLE that her pals were on hand to honor Project ALS’s 25th anniversary, which was hosted at Jazz at Lincoln Center.

“All the people who are a part of Project ALS go back that far with her,” Stiller told folks. “Everyone’s here on a personal level.”

According to the Mayo Clinic, ALS (amyotrophic lateral sclerosis) is a deadly, degenerative nervous system illness that affects nerve cells in the brain and spinal cord.

ALS, often known as Lou Gehrig’s illness after the baseball legend who was diagnosed with it in 1939, “often begins with muscle twitching and weakness in an arm or leg, trouble swallowing or slurred speech,” according to the Mayo Clinic.

According to the Project ALS website, Estess was diagnosed with the condition in 1997 and was urged by her doctor to “max out her credit cards and eat junk food.”

Instead, she launched Project ALS, which has raised over $90 million to fund its research toward a cure.

Stiller lauded Project ALS, calling it a “amazingly effective organization.”

“It’s difficult to deal with because there isn’t much hope for people when there isn’t a cure.” But Project ALS has given me hope,” Stiller told PEOPLE.

He went on to say that the organization had “worked so hard to get money for research funding, and they’re making real progress.” That’s what it’s all about.”

According to the ALS Association, the cause of the disease is unknown, and 90% of cases arise with no documented history or genetic basis. The majority of persons who develop ALS are between the ages of 40 and 70, with an average age of 55 at diagnosis, but there have been cases of ALS in people as young as their twenties and thirties. Men are 20% more likely than women to be diagnosed, while the prevalence increases with age.