Renée Zellweger

Strong women battling breast cancer. A sympathetic hero fighting for a cure. An ensemble of gifted actresses and a sexy charmer as their white knight. A three-hankie script and a four-hankie ending. Living Proof (Saturday, Oct. 18 at 9 pm/ET) might be Lifetime's most Lifetime-y movie ever. And yet the inspiring story, based on pioneering oncologist Dennis Slamon's dogged pursuit for a cure, took seven years to get to the screen — a struggle nearly as hard-fought as Slamon's battle to take his breast-cancer drug, Herceptin, to patients.

"Dennis Slamon became a hero to me," says scriptwriter Vivienne Radkoff, who had read Robert Bazell's 1998 book Her-2, chronicling Slamon's efforts to get Herceptin on the market. "I was obsessed, but something would always stop the project." One interested producer had to drop out after being diagnosed with breast cancer herself.

Eventually, Radkoff's script would find some big-name champions — producers Craig Zadan and Neil Meron (Chicago, A Raisin in the Sun), actress (turned producer) Renée Zellweger and playing Slamon, singer-actor Harry Connick Jr. "No one would make Vivienne's movie," Zadan says. "She brought the story to us, hoping that we could somehow force it through the system. We've done a lot of dramatic shows that we care about, but this seemed to be the most important of all."

See who else is in the impressive cast after the jump.