WHEN Omar Rodriguez finishes chemotherapy in February, he will return to the hospital for a dose of an mRNA vaccine. But it won’t be for COVID-19.

Rodriguez, 47, of Edinburg, Texas, was diagnosed with stage 3 colon cancer this summer. He has already had surgery to remove the tumor, but even after chemotherapy, his doctor told him there’s still a 70 percent chance his cancer will return in the next five years.

Rodriguez will be among the first people in the U.S. to receive a novel, personalized vaccine that harnesses the same mRNA technology used in Pfizer-BioNTech’s and Moderna’s COVID vaccines. This time, the vaccine won’t teach the body to target the coronavirus, but cancer cells, instead.

The vaccine is being made by BioNTech, the German pharmaceutical company that partnered with Pfizer last year to produce the first COVID vaccine to be authorized for emergency use in the U.S. The company is studying the experimental vaccine in a phase 2 clinical trial; Rodriguez is one of the participants.

BioNTech had its sights set on an mRNA vaccine long before the coronavirus swept the globe last year. The company was founded 13 years ago with the goal of developing cancer therapies, said its CEO, Dr. Uğur Şahin.

The German company isn’t alone: Scientists around the world had been working to develop mRNA vaccines for decades before the coronavirus pandemic pushed the technology into the mainstream. The seemingly endless possibilities include treating or curing chronic diseases, including HIV and cancer.

Strands of mRNA, or messenger RNA, are tiny snippets of genetic code that tell the body how to build proteins, essential building blocks of every cell in the body.

The idea behind an mRNA vaccine — whether for COVID or for cancer — is to use the genetic material to train the immune system to target a specific protein. For the coronavirus, it’s the spike protein on the surface of the virus. For cancer, it could be a protein on the surface of a tumor cell. Once the immune system learns to recognize the protein, it can create antibodies or T cells that fight and destroy it, along with the cells that carry it.

“Messenger RNA is a unique chemical entity,” said Dong Yizhou, an associate professor of pharmaceutics and pharmacology at Ohio State University. Dong is not involved with the BioNTech vaccine. “It’s a very simple code that you can apply to any protein or peptide of interest, so it can be very versatile.”

BioNTech chose to target colorectal cancer for a potential vaccine because of the disease’s relatively high rate of relapse.

The novel vaccine uses proteins unique to people’s tumors to train their immune systems to recognize cancer cells and then fight and hopefully kill the cells.

Additional trials are enrolling patients in Belgium, Germany and Spain, for a total of 200 people.

“It’s a very promising field, and we’re still at the beginning of the possibilities,” said Dong of Ohio State University.(SD-Agencies)