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Tweaked COVID vaccines fend off variants

Dozens of Americans are rolling up their sleeves for a third dose of COVID-19 vaccine — this time, shots tweaked to guard against a worrisome mutated version of the virus.

Make no mistake: The vaccines currently being rolled out across the U.S. offer strong protection again COVID-19. But new studies of experimental updates to the Moderna and Pfizer vaccines mark a critical first step toward an alternative if the virus eventually outsmarts today’s shots.

“We need to be ahead of the virus,” said Dr. Nadine Rouphael of Emory University, who is helping to lead a study of Moderna’s tweaked candidate. “We know what it’s like when we’re behind.”

Mutations occur whenever any virus makes copies of itself. Usually those mistakes make no difference. But if a lot of changes pile up in the spike protein — or those changes are in especially key locations — the mutant might escape an immune system primed to watch for an intruder that looks a bit different.

The good news: It’s fairly easy to update the Moderna and Pfizer vaccines. They’re made with a piece of genetic code called messenger RNA that tells the body how to make some harmless spike copies that in turn train immune cells.

The companies simply swapped out the original vaccine’s genetic code with mRNA for the mutated spike protein — this time, the one from South Africa.

Studies getting underway last month include a few hundred people, very different from the massive testing needed to prove the original shots work. Scientists must make sure the mRNA substitution doesn’t trigger different side effects.

On the protection side, they’re closely measuring if the updated vaccine prompts the immune system to produce antibodies — which fend off infection — as robustly as the original shots do. Importantly, lab tests also can show if those antibodies recognize not just the variant from South Africa but other, more common, virus versions as well.

Some good news: Antibodies aren’t the only defense. NIH researchers recently looked at another arm of the immune system, T cells, which fight back after infection sets in.

Lab tests showed T cells in the blood of people who recovered from COVID-19 long before worrisome variants appeared were able to recognize mutations from the South African version.

Vaccines trigger T cell production, too, and may be key to preventing the worst outcomes.

—AP

Immune-booster melts lung cancer tumors

A drug that helps the immune system fight cancer gave dramatic results when used with chemotherapy before surgery in patients with operable lung tumors, doctors report.

One out of four patients given chemo and the Bristol Myers Squibb drug Opdivo had no signs of cancer remaining once they ultimately had surgery, a study of about 350 such people found.

“They open the person up, and the tumors just melted away. It’s incredible,” said Dr. Roy Herbst, a lung specialist at the Yale Cancer Center.

He had no role in the study, whose results were reported at an American Association for Cancer Research conference in April.

Lung cancer kills more than 1.7 million people globally each year. Only about one-third of cases are caught early enough for surgery to help, but that’s still about 70,000 patients each year in the United States. The number is growing as screening of former or current heavy smokers expands, Herbst said.

Opdivo and similar drugs called checkpoint inhibitors work by removing a cloak that enables some cancer cells to hide from the immune system. They’re often used for various cancers after surgery, but many studies are testing them for use before surgery as well.

Dr. Patrick Forde at Johns Hopkins University led one such study of about 350 patients with lung cancers that had not spread widely. The cancers were not the type that can be treated with drugs that target certain gene mutations.

Patients were given three rounds of chemo and Opdivo several weeks apart or chemo alone. When they had surgery, no cancer remained in 24% of those given the combo versus 2.2% of those who received just chemo.

Whether the combo treatment improves survival remains to be seen; the study is continuing.

“This is a great next step” for furthering the immune system’s ability to attack lung cancer, said Dr. Antoni Ribas, a cancer specialist at the University of California, Los Angeles, and president of the group sponsoring the conference.

Seeing no evidence of disease at surgery in 1 in 4 patients means they “had an immune system that was really ready to go” with proper prodding, he said.

—AP