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It's been five years since Stacy Erholtz underwent an experimental treatment for blood cancer that used enough measles vaccine to inoculate 10 million people, and she's still celebrating her life, moment by moment.

"I'm not the kind of person who waits for the other shoe to drop," said Erholtz, 54, of Pequot Lakes. "I was prepared to die, and I didn't die," she said. "I believe God has a plan."

Dr. Stephen Russell, a professor of molecular medicine at the Mayo Clinic who spearheaded the treatment, said his research has failed to live up to his initial hope to use an engineered form of the measles virus as a kind of guided missile against multiple myeloma, a cancer that attacks white blood cells. Even so, he says, "Stacy has lived up to it."

Erholtz recently was a guest speaker at the International Oncolytic Virus Conference in Oxford, England, where she talked about her life and the exhausting treatments she endured since her diagnosis in 2004, at the age of 40.

"And then I focused on the viral therapies, the measles infusion, and how as cancer patients the chemo and the radiation can be so toxic, it can be so debilitating. The time for travel, the expense of it all, it just kind of drags on forever and you're never finished.

"But a treatment like viral therapy, for instance, for me, it was a 24-hour, very intense, extreme day, but 24 hours later it was over and I could leave the hospital."

With Erholtz as his living "proof of concept," Russell has spun off a company called Vyriad to advance the use of viruses as a way to target cancers, raising $10 million last year for clinical trials and more recently, $9 million to set up a 25,000-square-foot facility in the old IBM plant in Rochester.

Until about five years ago, Mayo Clinic didn't let its scientists license their discoveries for commercial use. Vyriad was an early beneficiary of a change in that policy. Russell said Mayo Clinic is an investor in the company and also contributed to the $9 million it raised to build offices, a manufacturing facility and research center in a massive building where IBM once made computer hard drives.

Other investors include the Rochester Area Economic Development Initiative Inc. and the Southeast Minnesota Capital Fund, a venture capital firm.

"Stacy is just a really great poster child for the field," Russell said in a telephone interview last week as he prepared for a gathering sponsored by the Mayo to mark Erholtz's fifth year without a general recurrence of the cancer.

"On the basis of Stacy, we obviously launched ourselves very aggressively into clinical trials in myeloma to prove that this is a reproducible outcome. And we did not get another Stacy."

Even so, he said, the research has made significant progress.

"She's fed up with being a unicorn," Russell said. "She wants other people alongside her who are responding [to viral therapy], so everything is about bringing that on."

An unusual case

Using the measles virus to target cancers had a major drawback: Because so many people have been vaccinated against it, they have antibodies that attack it.

Erholtz was unusual. She didn't have antibodies against the measles virus because she'd gone through two stem-cell transplants as part of her treatment for myeloma, which wiped them out. In addition, she sought the measles inoculation relatively soon after the myeloma flared up after her last stem-cell transplant, so the prevalence of cancer cells was unusually small compared with most other myeloma patients who seek treatment.

Finally, her cancer had a large number of mutations, which may have made it stick out to her immune system.

Vyriad switched from measles to vesicular stomatitis virus (VSV), which causes skin blisters in cattle in South America and the southern United States. People are not vaccinated against VSV, and few North Americans have been exposed to it, Russell said. Plus, labs have studied VSV for years and it's been engineered for use against a variety of cancers. Vyriad is using it to target colorectal cancer and T-cell lymphoma, a cancer found in the blood or lymph nodes.

Those cancers were selected because there is a significant need for treatment methods, Russell said.

"And we have seen some really quite promising activity, both in our preclinical models and in the clinic," he said.

"Our clinical trials plans at the moment have built in 200 patients over the next two years. But in addition to that, we have a lot of academic groups saying, 'Look, if you'll only give us some virus, we'll do a clinical trial … because we're really excited to test it.' "

In animal testing, he said, VSV has proved to be a powerful anti-cancer agent.

"With this new virus we have shown — in a mouse model of multiple myeloma — that a single intravenous dose can completely cure it," Russell said. "So we're still chasing down that outcome."

The virus that Vyriad is using was modified and tested in pigs by the U.S. Department of Agriculture at the Plum Island Animal Disease Center off the coast of New York. It didn't cause blistering in the animals, Russell said. It's now in the early stages of a trial with myeloma patients at Mayo.

Rochester made sense

Russell said it's been hard to raise money for the research. Venture capital firms liked the idea, he said, but wanted the company to set up shop in Boston or San Francisco to take advantage of the talent pool of regulatory affairs people, manufacturing experts, postdoctoral researchers and other scientists.

"They sort of looked at Rochester and said, 'You don't have all that there. You have Mayo Clinic, which is great, but you don't have an ecosystem in which you can confidently build a biotech company of the type you are talking about.' "

Russell, the CEO of Vyriad, said because of the company's strong relationship with Mayo, it made more sense to stay in Rochester. He said the company, with 10 employees, has a strong support team in place and expects to triple its workforce in the coming year and might hire a more seasoned CEO to take it forward.

"I wish I could tell you, 'Yeah, we've made it rain,' but we haven't yet," he said. "We remain convinced that it's achievable, and I'm optimistic that we are on the right path. We know that both the measles and VSV do have anti-tumor activity and so we know we've got the foot in the door, but it's just finding the right way to use these viruses."

Erholtz, meanwhile, has gone back to work part time at Grand View Lodge in Nisswa. She has a small foundation that she set up when she thought the measles vaccine was going to be a magic bullet against multiple myeloma. Now, she's planning to use it to set up a website that will highlight clinical trials for viral therapy against all types of cancer.

She said passing the five-year survival mark was just a milestone.

"I'm ready for some friends, for a community who aren't on daily chemos or monthly, weekly infusions," Erholtz said. "My initial hope when I first got diagnosed was to see my eldest of three [children] graduate from high school. I've now seen two graduate from high school, one wedding, another one in the works, and my son plays football for Bethel University. I can go watch him play football; I have energy to do so. It's pretty cool.

"I just kind of go one day at a time. I'm hopeful for my children and the next generation."

Dan Browning • 612-673-4493