While Covid-19 infection rates have taken a downturn in recent days, hospitalizations and deaths are still at all-time highs. The need for effective therapies to treat severe Covid-19 symptoms has never been greater. Eli Lilly is one of the pharmaceutical companies taking on the task of developing these therapies, and a new antibody therapy trial released last week proved one combination therapy to be quite effective at reducing viral load in Covid-19 patients.
The study aimed to determine the effect of bamlanivimab (BAM) as an antibody monotherapy and bamlanivimab paired with etesevimab (ETE) as an antibody combination therapy to reduce the viral load for severe SARS-CoV-2 patients. 613 patients were given BAM monotherapy, BAM and ETE combination therapy, or a placebo treatment.
The BAM monotherapy yielded results only slightly better than the placebo group. The change in log viral load for the placebo group after 11 days was -3.80, whereas the change for a 700mg dose of BAM was -3.72 for 700 mg, -4.08 for 2800 mg, and -3.49 for 7000 mg. Across all dosages, it seems that the BAM monotherapy yielded around the same reduction in viral load as the placebo group did naturally over the time period.
Researchers additionally tested BAM in conjunction with ETE to see if the combination therapy would yield a greater result. It did just that. After 11 days, while again the placebo reduction in viral load was -3.80, the combination therapy reduction was -4.37. According to the researchers, this was a statistically significant result, whereas the BAM monotherapy did not yield statistical significance.
The secondary outcomes of this study also note that none of the therapies completely clear the virus from the patient. Neither the combination therapy nor the BAM monotherapy prompted two consecutive PCR negative test results for SARS-CoV-2 within the 29 days of the start of the study. This means that none of the therapies completely cleared the virus from the patient. The remaining bits of the virus may not be enough to transmit to another host, but it’s noteworthy nonetheless.
Another noteworthy piece of data from the secondary endpoints, and arguably a primary endpoint to many, is that all doses of the BAM monotherapy and the BAM/ETE combination reduced hospitalizations in patients with severe Covid-19. Among the placebo group, 5.8% of patients were hospitalized during the course of the trial. That percentage dropped to 1% for the 700 mg group, 1.9% for the 2800 mg group, 2% for the 7000 mg group, and .9% for the combination therapy.
This is a positive result. It seems that some therapies in conjunction can yield greater results than monotherapies. This may speak to the strength of the virus to evade neutralizing antibodies or perhaps therapies in conjunction simply prompt a stronger immune response. As more data becomes available about the BAM/ETE combination therapy, greater confidence can be taken in distributing this therapy to those in overcrowded ICUs and hospitals across the country.
Though a limiting hesitation remains. We don’t know the exact strain the patients involved in this study were infected with. Emerging data is indicating that mutant strains, like those originating in the UK and South Africa, may be immune resistant to neutralizing antibodies. Meaning the variants may resist antibodies from previous infection, antibodies delivered via vaccine, or even antibodies used in severe Covid-19 therapies.
While we await new studies working to specifically target new variants with Covid-19 combination therapies, these results are encouraging. Bamlanivimab-etesevimab combination therapy could save countless lives that remain at risk. We eagerly await the results of its next stage of trial.