Kathy Dailey Ripperger loves being fit and active. Even with her busy schedule working in creative media for a movie studio, she finds a way to exercise every day—from yoga and Pilates to walking, running and hiking.

So when she found out that she had stage 4 melanoma that had spread to her liver and lungs, she was stunned.

"You could have knocked me over with a feather," Kathy says. "I had just gone on a vacation where I'd done a 6-mile trail run. I was like, 'How can I be sick?'"

But most devastating of all was her prognosis. Even with chemotherapy, the oncologist told her, she had a year or two to live.

Kathy left the doctor's office in a daze. As soon as she was back in her car, she called Ron Ripperger, her then-boyfriend of 13 years. They both started crying.

"You always know death is out there," she says. "But at 55, you don't think it's going to be your time."

Read: Virtual Second Opinion: Here’s What to Know

Kathy's diagnosis came on a Friday, and over the next three days, she went through a roller coaster of emotions: tears one minute, anger and yelling the next, and then depression.

But by Sunday night, she'd made up her mind.

"I just said, 'No, I'm not ready to go,'" Kathy says. "Something in me clicked, and I kind of had that aha moment: No, I don't have to take his word for it. I was sitting with Ron on the couch and we were like, 'Yes, we're going to fight this.'"

The next day, her boss recommended another oncologist, who immediately referred Kathy to Dr. Omid Hamid, chief of Translational Research and Immunotherapy and director of Melanoma Therapeutics at The Angeles Clinic and Research Institute, an affiliate of Cedars-Sinai.

By Wednesday, Kathy and Ron were sitting in Dr. Hamid's office.

"It was a breath of fresh air," she says. "Dr. Hamid and the whole team just gave me so much hope. They made me feel like, 'Hey, we've got your back. We're going to take good care of you."

Dr. Hamid felt Kathy was an excellent candidate for one of the institute's melanoma clinical trials. The trial was studying two new drugs called "checkpoint inhibitors"—a new kind of cancer treatment called immunotherapy.

"Unlike chemotherapy, immunotherapy doesn't kill tumor cells directly," Dr. Hamid explains. "Instead, it helps the body's own immune system to detect and destroy the cancer."

Kathy had her first immunotherapy infusion on Oct. 17, 2013. It was an all-day affair, with two separate infusions and several blood draws. She and Ron went home exhausted.

"I'm not used to being the patient. I'm used to being a caregiver," she notes. "Everyone was super nice, but I was like, 'I don't want to be here. I don't want to be a cancer patient.'"

By that night, the side effects began kicking in: extreme chills, followed by intense hot flashes, like flames shooting down her spine. She threw up, lost her appetite and soon even lost her hair—a rare side effect for immunotherapy.

It was rough, but Dr. Hamid and his team were there to manage each of those side effects. She learned to call them as soon as she felt a new symptom, and she followed their instructions exactly.

After 12 weeks of treatment, her tumors had shrunk by 36%. That was good news, but shortly afterward, a blood test revealed that Kathy's liver enzymes were elevated. The treatment had become too toxic for her. She would have to start on steroids and stop the infusions.

At first, she panicked. "No, no, no, I'm on a schedule, I need to get to 100%," she argued.

Dr. Hamid calmed her down, explaining that checkpoint inhibitors can often continue to work—even without additional infusions. In other words, once the immune system has "learned" how to fight the cancer, it may not need ongoing infusions to keep "teaching" it.

Indeed, six weeks later, her tumors had shrunk to 50%. She was feeling better and even started running again. As the months went by, her life returned to normal, and the tumors continued to shrink.

Eventually, there was no active cancer in her body.

"I feel like a walking miracle," Kathy says.

The two drugs in Kathy's clinical trial are now both FDA-approved. Still, immunotherapy doesn't work for many patients.

"Not everyone has the response that Kathy had," Dr. Hamid explains. "But through research, we are working to make the treatment more effective and less toxic."

Today, Kathy's scans show no active cancer, and her life is full. She and Ron married in 2017, she celebrated her 60th birthday in 2018 and she has become a grandmother—twice. She continues to love her job, occasional travel and, of course, her daily exercise.

Her advice for other cancer patients?

"Don't be afraid to get a second opinion," she says. "Do your research and find a doctor who will give you a sense of hope and find the right treatment for you."

Most importantly, keep living your life.

"I asked Dr. Hamid once, 'Is there something I can do to repay you?'" Kathy adds. "And he said, 'Just live. Just live your life.' And that's what I would tell other patients. If there's something you've been wanting to do, do it. It's not over! Get out there and live and make the most of every day."