New coronavirus treatments are racing along the development timeline so quickly that it's hard to tell who's in the lead from one moment to the next. Until recently, Regeneron Pharmaceuticals (NASDAQ:REGN) appeared to be furthest ahead with a new COVID-19 treatment, but Eli Lilly (NYSE:LLY) and the big pharmaceutical company's new collaboration partner, AbCellera, have already beaten Regeneron to an important milestone.

Eli Lilly recently began dosing patients with LY-CoV555, an experimental antibody that was isolated from one of the first U.S. patients to recover from COVID-19. Regeneron's been progressing at top speed with a similar program called REGN-COV2, but patients aren't expected to begin taking it until later this month.

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What's in store for the future of COVID-19 treatment? Here's what you need to know.

Room for improvement

While remdesivir has already received emergency use authorization (EUA) to treat COVID-19 patients, it's a broad-spectrum antiviral that's been around a long time.Gilead Sciences (NASDAQ:GILD) had already been aiming the candidate at different viruses for a decade, unsuccessfully, when SARS-CoV-2 reared its ugly head.

Despite remdesivir's early entry, its limited benefit means demand for a highly effective COVID-19 treatment will probably still be sky-high once we know more about LY-CoV555. While there's some evidence remdesivir boosts recovery rates, there's still a lot of room for improvement. Gilead recently released results from the phase 3 Simple trial that show patients' chances of clinical improvement at day 11 were 65% higher when treated with remdesivir plus standard care, compared to patients given standard care and a placebo.

Unfortunately, patients treated with a 10-day course of remdesivir weren't any more likely to show improvement at the same observation point. Deaths were four times more common among patients treated with standard care, but with just six deaths among 583 moderately affected COVID-19 patients in total, the benefit wasn't clear enough to be considered significant.

Remdesivir's a small-molecule drug that inhibits an enzyme hijacked by viruses to replicate themselves. But the LY-CoV555 program is taking a much different approach. Lilly's COVID-19 treatment candidate is a protein that attaches itself to spikes on the surface of SARS-CoV-2, which should prevent the virus from entering host cells in the first place.

A surprising first

Over the past three decades, Regeneron built a reputation for quickly developing new therapeutic antibodies, including an Ebola disease candidate widely expected to be approved by the Food and Drug Administration this fall. Regeneron has employed a similar technique to develop REGN-COV2, a program that will employ a combination of different antibodies working in concert to stop SARS-CoV-2 from replicating.

We know Regeneron's approach worked with Ebola patients during a study conducted in 2018, which makes it a little surprising to see a privately held company appear from nowhere to take the lead in this race. In all fairness to Regeneron, AbCellera had a great deal of help before signing a collaboration deal with Eli Lilly: from the Defense Advanced Research Projects Agency (DARPA) -- an agency tasked with developing emerging technology for use by the military -- and the National Institute of Allergy and Infectious Diseases (NIAID).

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Something to gain?

Investors considering shares of Eli Lilly or Gilead Sciences should know that COVID-19 therapies probably aren't going to make a major impact on their bottom lines, at least not for very long. While LY-CoV555 sales could be a big windfall for most drugmakers, Eli Lilly already has nine products on pace to generate more than $1 billion in sales this year. And over the past twelve months, Gilead Sciences reported $22.7 in total revenue.

Annual sales of Tamiflu peaked at $1.8 billion, and it's an orally available therapy. We don't know if LY-CoV555 will be delivered in the form of an injection or an infusion, but it won't be an easy oral treatment. While sales of a COVID-19 treatment might not make a big difference to Eli Lilly, Regeneron's a smaller, younger company. Over the past year, the biotech reported $8.0 billion in total sales.

During the first three months of 2020, Regeneron leaned on its top-selling product, a blindness-preventing injection called Eylea, for 64% of total sales. Unfortunately for Regeneron and its shareholders, incoming competition could begin pressuring sales of Eylea around a year from now.

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