Once again, we see how rent-seeking through patents is the problem, and not the solution for developing new drugs.
Here is the money quote on all of this to my mind, "The attractive profile of GS-441524 from both manufacturing and clinical perspectives raises this question: Why hasn’t Gilead opted to advance this compound to the clinic? We would be remiss for not mentioning patents, and thus profits. The first patent on GS-441524 was issued in 2009, while the first patent for remdesivir was issued in 2017."
Gilead has a long history of sacrificing the public health to the altar of profits, so this should be no surprise.
As for the potential of GS-441524, there is significant evidence that it is at least as good, if notbetter than, remdesivir:
In the midst of a pandemic like Covid-19, for which there are no FDA-approved drug treatments, hope is important. That’s one reason why remdesivir, an antiviral drug that Gilead Sciences originally made to fight Ebola, has been propelled into the spotlight with the hope that it can stop, or at least curtail, the ravages of SARS-CoV-2, the virus that causes Covid-19.
As chemists, we are troubled by the challenges to mass producing remdesivir. We aren’t alone. On the day that results from the two trials emerged, Gilead CEO Daniel O’Day praised the chemists behind the drug, saying he is “proud of the team because this is a complicated chemical process. It takes many, many steps.”
But does it really have to be that complicated? O’Day’s admission is interesting given that Gilead has another compound in its pipeline that is easier to make, has been shown to be effective against coronavirus in animal models, and is potentially as effective as remdesivir, if not more so.
Some background: Remdesivir works by interfering with the cellular machinery that allows viruses to replicate inside a human host. It is a pro-drug, meaning it must be metabolized and undergo a sequence of five bioactivation steps before it becomes GS-441524 triphosphate, the active compound that impedes viral replication.
Remdesivir isn’t Gilead’s only antiviral nucleoside analogue. The company has also developed GS-441524, another pro-drug that, as its name suggests, the body also converts into GS-441524 triphosphate, but in just in three steps. GS-441524 is easier to synthesize than remdesivir, requiring three steps instead of the seven needed for remdesivir.
Researchers initially thought that remdesivir would be activated more quickly than GS-441524 in human cells infected with the SARS and MERS coronaviruses. Yet data from primary human airway epithelial cells — one of the most clinically relevant cell-based models of the human lung — showed no statistically significant difference in potency between the two compounds. These data align with previous reports on the similar effectiveness of remdesivir and GS-441524 in coronavirus-infected cat cells. When GS-441524 was used to treat cats with feline infectious peritonitis, a progressive and usually fatal disease caused by a coronavirus, it displayed remarkable safety and therapeutic efficacy, with 96% of cats recovering after treatment.
Data in cats and primates have pointed to GS-441524’s safety. In the study using GS-441524 to treat feline coronavirus, the researchers noted its “impressive” safety profile when administered at high doses, and reported that no systemic signs of toxicity were observed over 12 to 30 weeks of treatment. In primates, GS-441524 was found to be present at high concentrations in the blood (1,000-times higher than remdesivir) with no apparent adverse effects.
When viewed through a different lens, the initial results from the NIAID-sponsored trial are more encouraging than they would seem. The active agent, GS-441524 triphosphate, clearly exerts antiviral activity against SARS-CoV-2 in humans, as supported by the accelerated recovery rates in advanced Covid-19 patients enrolled in the trial. Our analysis of preclinical and clinical trial data strongly suggests that early and direct administration of GS-441524 should be considered as a synthetically simpler and potentially more effective alternative to remdesivir, especially as GS-441524’s remarkable safety would enable higher dosing.