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Scientists still lack conclusive proof that the two anti-Covid drugs given to Donald Trump are clinically effective.
UK researchers point out that both medicines – remdesivir and REGN-COV2 – have still to complete the large-scale, randomised trials needed to demonstrate fully their ability to counter Covid-19 in patients. And many have criticised US authorities for their failures to carry out such trials. This has undermined efforts to find effective medicines to treat people affected by the disease.
“If President Trump gets better, we will still not know if those drugs played a role in his recovery or not. They may have been critically important or played no part at all,” said Professor Martin Landray of Oxford University. “That means when we come to treat the next patient hospitalised with Covid, we will still be none the wiser about the usefulness of those drugs.”
By contrast, Britain has adopted a policy of running blind, randomised trials to test drug efficacy through the Recovery testing programme – founded by Landray and Peter Horby, also of Oxford University. It compares responses of patients who get a treatment with those who are given a placebo. In this way, British scientists pinpointed the effectiveness of dexamethasone, a cheap steroid, in treating Covid while they demonstrated the uselessness of the much-touted drug hydroxychloroquine.
Last week, Recovery researchers launched their trials to test the effectiveness of REGN-COV2 when the first five patients, hospitalised with Covid complications, were given the drug. REGN-COV2 is a combination of two artificial antibodies, called monoclonal antibodies, and over the next few weeks, thousands more UK patients will be recruited in a trial of its effectiveness.
Horby said on Saturday he believed REGN-COV2 had real potential. “Of the drugs that are available, it’s one of the most promising,” he said. And Landray shared this optimism. “It has real potential. However, at present all we know is that it reduces viral load, the amount of virus in a patient. That tells us this is a drug that is bad for the virus. But we don’t yet know whether it is actually good for the patient. Could it have side effects? Is it better for children or the elderly, or people on ventilators? We need randomised trials to find that out.”
Trials of the other drug given to Trump, remdesivir, have also produced encouraging results, although again they are not conclusive. One trial in China earlier this year had to be stopped because it could not recruit enough patients, while a later, larger trial in the US showed that those given the drug spent less time on ventilators and that those given the drug had slightly better survival rates than those given placebos. However, the difference was not statistically significant.
“Remdesivir seems to speed up the time of patients’ recovery, but do more patients actually survive? We don’t know,” added Landray. The answer to that question is now likely to be supplied by a World Health Organization trial of remdesivir, expected to be completed in a few weeks.
The UK Recovery programme is now carrying out randomised trials of several other potential Covid treatments, including the antibiotic azithromycin and an anti-inflammatory drug known as Tocilizumab – as well as “convalescent plasma” derived from blood plasma taken from recovering Covid patients. Results from these are expected over the next few weeks.
“If we can find a couple of treatments that tackle the worst excesses of Covid-19, we could make the disease much more manageable, something more like seasonal influenza, and that would make a major difference to our lives,” added Landray. “The only way we will get that is to carry out careful, randomised trials.”
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