The Grateful Dead has lost one of its founding members.

Bob Weir, who established the psychedelic rock band in 1965 alongside Jerry Garcia, Phil Lesh, and Ron McKernan, has died, his family announced on January 10. He was 78.

“It is with profound sadness that we share the passing of Bobby Weir,” the family wrote in a post on his Instagram page. “He transitioned peacefully, surrounded by loved ones, after courageously beating cancer as only Bobby could. Unfortunately, he succumbed to underlying lung issues.”

The guitarist’s loved ones noted that even as he faced medical woes, he refused to be sidelined, even taking the stage with Dead and Company in his native San Francisco in August just weeks after he began receiving cancer treatment.

“Bobby’s final months reflected the same spirit that defined his life,” the statement continued. “Those performances, emotional, soulful, and full of light, were not farewells but gifts. Another act of resilience.”