Someday, we may have a vaccine that prevents all types of cancer, especially the more deadly types, like lung cancer. It’s an area of intense medical research. For now, there are only three cancer vaccines approved by the U.S. Food and Drug Administration. However, you may have read news articles about a vaccine developed for lung cancer in Cuba called CIMAvax. Here’s what to know about this drug.

What Is a Cancer Vaccine?

The immune system helps fight things that could make you sick, such as bacteria or viruses. A vaccine boosts your immune system’s ability to do this. This is important because cancer has ways to trick the immune system so it doesn’t recognize tumor cells as harmful or doesn’t attack cancer cells even if it recognizes them as a threat.

Cancer vaccines are called biological response modifiers because they stimulate or restore the immune system’s ability to fight infection and disease, according to the National Cancer Institute. Cancer vaccines can help prevent cancer from developing (preventive or prophylactic vaccines) or help treat cancer once it has developed.

The FDA has approved two types of preventive vaccines, one for Hepatitis B and another for human papilloma virus-associated cancers. The Hepatitis B virus can lead to liver cancer, while HPV can cause cervical, anal, vaginal, vulvar, penile and some head and neck cancers. The FDA has also approved a treatment vaccine for some types of metastatic prostate cancer.

Currently, there is no FDA-approved lung cancer vaccine, says Dr. David Carbone, medical oncologist and director of the Thoracic Oncology Center at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute.

CIMAvax Lung Cancer Vaccine

Researchers at Cuba’s Center for Molecular Immunology developed a lung cancer vaccine called CIMAvax. Their studies showed that the vaccine was well-tolerated and that some patients seemed to do better after receiving it, says Dr. Jorge Gomez, an assistant professor of medicine, hematology and medical oncology at Mount Sinai Hospital in New York, who was not involved in the studies in Cuba.

CIMAvax is a vaccine against a molecule called EGFR, Gomez says. EGFR is a normal molecule found on both healthy cells and lung cancer cells. It’s also highly expressed in some patients with lung cancer.

Gomez says that in the 1990s, cancer researchers believed EGFR might drive lung cancer growth, so they developed drugs to target the molecule. For the most part, they didn’t work, he says, except in one specific case where EGFR is actually abnormal, or mutated. “This was a big success in lung cancer – the recognition that some patients have abnormal EGFR that drives cell growth,” Gomez says. In these patients, EGFR is always turned on, so it continues to signal and promotes growth. About 15 percent of lung cancer patients, usually those who never smoked, have mutated EGFR. “Now we have drugs that work significantly better in this subset of lung cancer patients,” Gomez says.

The CIMAvax vaccine, however, stops the signaling of normal EGFR, Gomez says. In a phase 3 clinical trial in Cuba – designed to evaluate the effectiveness and safety of a drug – 405 patients were randomly assigned to either receive the vaccine or not receive it after completing four to six courses of chemotherapy. Participants who received at least four doses of CIMAvax survived an average of two months longer than participants who didn’t. Unfortunately, Gomez says, this was not a statistically significant difference. However, when the researchers used different statistics in a post-hoc analysis, they found a three-month increase in survival, which is statistically significant.

Because the CIMAvax studies were conducted outside the U.S., the FDA will not use the results to approve drugs for use in the U.S. So, the Roswell Park Cancer Institute in Buffalo, New York, is currently enrolling participants in a two-part clinical trial in the U.S. for stage 4 lung cancer patients who have already received chemotherapy and have finished their first-line treatment.

The first phase of the trial is designed to study the appropriate dose of CIMAvax, while the second is to treat patients with the vaccine to see how it works, Gomez says. In this trial, participants will receive CIMAvax in conjunction with the immunotherapy drug nivolumab (Opdivo), so the study isn’t a replica of the clinical trial in Cuba. “The study at Roswell will not tell us if getting the vaccine is better or not better,” Gomez says. “It’s just raw numbers to tell us how well it works with nivolumab. We still need trials to show if adding the vaccine can actually improve things over not getting the vaccine.”

CIMAvax is not the only lung cancer vaccine in clinical trials in the U.S. A search of finds approximately 160 studies of lung cancer vaccines, although only about 19 are actively recruiting. However, Gomez says, the trials conducted to date have not produced positive results.