In-Depth on the search for COVID's 'holy grail,' an antiviral pill

3 pills advancing in trials
Posted at 2:59 PM, May 18, 2021
and last updated 2021-05-19 18:57:12-04

SAN DIEGO (KGTV) -- Even though COVID cases have been on the decline nationwide, scientists are bracing for the possibility that SARS-CoV-2 will become a seasonal virus.

That’s why even as states lift mask mandates, researchers are still racing to find what they call the “holy grail” treatment: an antiviral pill. And at least three potential drugs are showing promising signs in clinical trials.

UC San Diego virologist Dr. Davey Smith is overseeing government-sponsored trials on two of those pills.

“It has become one of those holy grails, if we could have a therapy that people could take at home once they have early COVID,” he said.

Currently, the best early treatments we have for COVID are lab-made antibodies. The problem is that these monoclonal antibodies are expensive and challenging to administer.

Each treatment has to be infused into a patient’s blood. The process takes time, staff and space at clinics like Family Health Centers of San Diego.

“What we've wanted from the beginning is something that's easy, that's pill form, that we could use really quickly. The way we use [Tamiflu], which is an oral antiviral agent for influenza,” said FHCSD assistant medical director Dr. Christian Ramers.

Before a drug gets authorized by the Food and Drug Administration, it has to undergo three phases of human trials.

Pfizer has a potential pill in phase 1, the inscrutably named PF-07321332. Phase 1 is the stage where scientists work to find the optimal dose while monitoring its safety. Pfizer’s phase 1 trial involves 60 people.

PF-07321332 was custom-made for SARS-CoV-2.

Another promising candidate is a drug called camostat, manufactured by Sagent Pharmaceuticals.

The drug was authorized in Japan for pancreatitis in the 1980s, although it is not approved in the United States, Dr. Smith said.

The Pfizer drug and camostat are being tested in the ACTIV-2 trials backed by the National Institutes of Health, which Dr. Smith oversees.

Camostat just finished phase 2, where researchers begin to gauge the efficacy in a few hundred volunteers while continuing to collect safety data. Dr. Smith said Camostat will enter phase 3 “any day now.”

The drug that’s furthest along is a pill from pharmaceutical giant Merck called molnupiravir, which is not part of the ACTIV-2 trial.

“The Merck drug is further along because it was originally made for SARS Co-V1 and for another coronavirus called MERS,” Dr. Smith said.

That pill, which Merck is developing in collaboration with Ridgeback Biotherapeutics, is now in a phase 3 trial involving about 1,500 volunteers. Large-scale phase 3 trials are the final step to prove a drug is safe and effective.

All three pills are designed to be taken within the first few days after someone develops symptoms, before they’re sick enough to be hospitalized. The pills contain tiny molecules that disrupt the virus’s ability to replicate.

“This is just like throwing a monkey wrench in the machinery to stop that virus from making copies of itself and really buy time for our own immune systems to get the upper hand and clear the virus,” said Dr. Ramers.

All of the trials are still blinded, meaning even Dr. Smith doesn’t yet know the results, but he expects one of these pills will be ready and authorized before the end of the year.

Camostat and the drug from Pfizer are being tested at locations in San Diego including UCSD and Kaiser. Researchers are still actively recruiting volunteers to participate in the trials who have been recently diagnosed with COVID.