JUDY WOODRUFF: Now: a promising lung cancer treatment from Cuba that’s drawing attention from U.S. patients.

Some Americans are already traveling there to try the drug, in the hopes of stopping their cancer from growing. Former President Obama cleared the way for collaboration between both countries on such research, and clinical trials have started. Those trials may take years. But early results have some researchers intrigued by this new form of immunotherapy.

Special correspondent Amy Guttman has the story.

AMY GUTTMAN: Mick Phillips travels from his home near Green Bay, Wisconsin, to Cuba once a year. Despite his passion for vintage cars, that’s not what draws him. He goes there for CimaVax, a Cuban-made drug used to treat cancer that’s kept him alive longer than any doctor predicted.

MICK PHILLIPS, Lung Cancer Patient: So, I have this little lunch box here that’s insulated. And, in there, I carry my medication and I also carry gel packs.

AMY GUTTMAN: Phillips is 69 years old and owns an industrial pump factory, where he continues to work every day. He was first diagnosed with non-small cell lung cancer seven years ago. After chemotherapy and radiation treatment, his cancer went into remission.

But it returned less than a year later, in 2011. He did another round of chemotherapy, then took CimaVax, and is now in remission. Fewer than 5 percent of stage 4 lung cancer patients like Phillips survive for five years. But CimaVax appears to be improving those odds for some.

MICK PHILLIPS: I started the CimaVax and have been cancer-free ever since then.

AMY GUTTMAN: And how long were you supposed to live once you went into remission?

MICK PHILLIPS: The prognosis was maybe six months to a year.

AMY GUTTMAN: How many years ago was that?

MICK PHILLIPS: That was six years ago.

AMY GUTTMAN: At La Pradera, a hotel-like hospital near Havana, Phillips pays about $5,000 for an annual supply of CimaVax. The doctor visit costs only $50.

Back in Wisconsin, Phillips says he’s lucky that his oncologist, Dr. Timothy Goggins, continues to treat him. American doctors can’t prescribe CimaVax, because the Food and Drug Administration won’t approve it until U.S. clinical trials can prove its effectiveness.

DR. TIMOTHY GOGGINS, Fox Valley Hematology & Oncology: How are things going?

MICK PHILLIPS: Oh, pretty good.

AMY GUTTMAN: Dr. Goggins monitors Phillips with regular scans.

DR. TIMOTHY GOGGINS: Compare this to where he is today, no evidence of growth necessarily in that area. In fact, there might even be shrinkage. I would have expected, in this case, further growth, definitely within the lungs. I’m surprised Mick’s still here.

So, I do believe that, outside of divine intervention, there’s some sort of scientific basis to what he’s doing.

AMY GUTTMAN: Published results of trials done in Cuba show those given CimaVax lived, on average, as little as three months and as much as 11 months longer than those not given the drug. Some did even better.

Dr. Michael Caligiuri, president of the American Association for Cancer Research says, even with the success in Cuba, there must be further study.

DR. MICHAEL CALIGIURI, American Association for Cancer Research: Whenever there’s an early evidence of efficacy in a single population, a single institution study, the chance that it will be replicated inter-institutionally is real, but not a given.

AMY GUTTMAN: This facility outside Havana produces CimaVax. It doesn’t kill cancer cells. Instead, it engages the patient’s immune system to reduce the protein cancer thrives on.

What makes this different from other immunotherapies is, it uses a patient’s own antibodies, rather than manufactured ones, which carries fewer side effects and is cheaper.

Researchers at Roswell Park Cancer Institute in Buffalo, New York, waited four years to get the green light for clinical trials of CimaVax that began in January.

The institute’s chair of immunology, Dr. Kelvin Lee, was in Havana recently for a conference.

DR. KELVIN LEE, Roswell Park Cancer Institute: In many cases, the tumors just stop growing. They’re there, but they don’t get any bigger. The patient has the possibility of going on for a very long time.

AMY GUTTMAN: CimaVax is given by injection and is considered a therapeutic drug for now. But Dr. Lee and his colleagues are applying for funding to test it as a preventive vaccine for high-risk patients.

DR. KELVIN LEE: Because it is safe, inexpensive, easy to administer, you could use it, potentially, to prevent lung cancer.

AMY GUTTMAN: The embargo that prevented Cuba’s access to American pharmaceuticals led the late President Fidel Castro to invest heavily in developing medicines and vaccines.

Former President Obama traveled to Cuba last year. He later announced new policies making it easier for American researchers to apply for FDA approval to trial Cuban drugs in the United States.

Mick Phillips voted for President Trump, but Mr. Trump has vowed to rollback some of Obama’s policies when it comes to Cuba relations. Phillips fears what that could mean.

MICK PHILLIPS: I am concerned that access to this medication will go away for many, many people.

AMY GUTTMAN: Dr. Lee says it’s all part of a potential change in the way doctors approach cancer treatment.

DR. KELVIN LEE: There is an idea that’s developing of converting cancer into a chronic disease. We give you a pill that you take every day, and it allows you to live a perfectly normal life.

AMY GUTTMAN: Outside Cuba and the U.S., there’s great interest in CimaVax. It’s approved in five different countries. Worldwide, 5,000 patients have been treated with the drug since 2011, 1,000 of them Cubans.

But no one sees CimaVax as a magic pill. Twenty percent of vaccinated patients have not lived longer than the average survival of the unvaccinated group.

Phillips’ doctor, Tim Goggins, says there are many unknowns about the drug.

DR. TIMOTHY GOGGINS: At some point in time, the immune system will probably not respond to that cancer cell. The cancer cells find a way around it.

AMY GUTTMAN: Mick Phillips hopes the new American president will allow the progress he credits to Cuban drugs to continue.

MICK PHILLIPS: The key is that the political relations staying in place. If that relation stays as it should, I believe that we can all benefit from it.

AMY GUTTMAN: Since taking office, President Trump has not said much more about his approach toward Cuba. It’s still unclear what this could mean for future trials of the drug.

For the PBS NewsHour, I’m Amy Guttman reporting from Havana.