At present, there are only two treatment options for Covid-19, either an immune response, that is, the body’s own immune system attacks and fights the viral infection, or a treatment of the symptoms when the infection is already underway.
While vaccines and good health can facilitate the body’s own ability to deal with the infection, medical treatments have been few. Remdesivir is currently the only drug-approved treatment and the effects are, just like the side effects, disputed. In SARS-COV-2 mutations in a patient with a persistent viral load treated with convalescent patient plasma and Remdesivir, resulted in no less than 7 mutations in the spike (including N501Y of the English and South African variant), and decreased sensitivity to antibodies occurred, a new study showed.
But a third course of treatment may be on the way. The pharmaceutical company Pfizer announced on Tuesday that it has begun its phase-1 study of its new drug, PF-07321332, which is an orally administered antiviral drug against Covid-19. In addition, it is thought to be able to work against all variants of Coronavirus – including the mutations that continuously appear and risk making the vaccine unusable.
Addressing the COVID-19 pandemic requires both vaccine prevention and targeted treatment for those affected by the virus. Given the SARS-CoV-2 mutation and the continuing global impact of COVID-19, it seems likely that access to therapeutic options both now and beyond the pandemic will be crucial, said Dr. Mikael Dolsten, Pfizer’s lead researcher, in a press release.
The medicine comes in pill form and is a so-called protease inhibitor. It is a form of medication that has been used for a long time as antiviral drug, for example in HIV medications and in what is often called antidepressants. PF-07321332 acts similarly to these by preventing the production of an enzyme, in this case one that all Coronaviruses, including SARS-CoV-2, need to be able to initiate their copying process in our cells.
When a virus enters the body, it injects genetic material through cell membranes and this causes the virus to “take over” the cells and cause them to produce more viruses, which in turn spread to other cells and repeat the process until we become ill or our immune system manages to fight them.
By blocking that process, one succeeds in preventing the virus from spreading further in the body, which gives the immune system significantly greater opportunities to fight the infection. What this means in practical terms is that the medicine is given when an infection has been detected, preferably as early as possible in the infection, and thus the symptoms become less serious. Fewer affected cells cause fewer symptoms, less spread in the body with a less severe immune response – something that in itself can be harmful to the patient.
“We have designed PF-07321332 as a potential oral treatment that could be prescribed at the first sign of infection, without the patients being in hospital or in critical care. At the same time, Pfizer’s intravenous antiviral candidate is a potential new treatment option for patients in hospitals. Together, the two have the potential to create a start-to-end treatment paradigm that complements vaccination in cases where the disease still occurs,” continued Dr. Dolsten.
According to initial studies conducted by Pfizer, their medicines have shown a significant inhibitory effect on the SARS-CoV-2 virus, but also other variants of Coronavirus, as well as several different mutations of SARS-CoV-2. In addition to the pill form, an intravenous solution is also being developed that will be given in more severe cases of infection. The Phase-1 study begins with a small number of volunteers and will be conducted in the United States in the spring. After that, it is hoped to be able to start phase 2 studies with more participants already during the summer or no later than the beginning of autumn.
Pfizer believes that the combination of the drug in its two different forms could mean a significant advance in the fight against the pandemic, but that it will not in itself be able to replace a mass vaccination program – which is a given since the company will earn billions from its own vaccine against Covid-19.
