Remdesivir has emerged as the drug to treat the new coronavirus infection, but using it alone is not enough to help patients fight the disease, researchers said in a recent study.

Thus, physicians may have to use it with other complementary therapies, they added.

The study, published in the New England Journal of Medicine, showed that remdesivir shortened the treatment period for Covid-19 patients but was insufficient to treat them fully. Although remdesivir was useful in hospitalized patients requiring supplementary oxygen, it failed to meet the expectation for lowering mortality, the study showed.

The study said researchers needed to find other therapeutics or antiviral agents combined with remdesivir to improve patient outcomes in Covid-19.

Lilly’s rheumatoid arthritis drug baricitinib (brand name: Olumiant) and CytoDyn’s HIV drug leronlimab are being cited as the most likely medications to maximize remdesivir’s therapeutic effect on Covid-19.

U.S. researchers recently registered a clinical trial on a combo therapy of remdesivir and baricitinib, and CytoDyn is also preparing a trial on leronlimab plus remdesivir in the U.S.

Baricitinib drew attention after the release of genomic information of the Covid-19 virus in January revealed that the virus utilizes “ACE2,” a cell-surface protein when entering the human body.

A research team led by Professor Justin Stebbing at Imperial College searched for numb-associated kinase (NAK)-targeting drugs involved in ACE2’s endocytosis. It found 47 licensed medications out of the 378 candidates. Among the 47, the team picked baricitinib as the best candidate for Covid-19 treatment.

The study was published in The Lancet in early February.

The researchers said that baricitinib would be effective on seriously ill Covid-19 patients’ increased cytokine because the agent blocks the viral entry and inhibits JAK-STAT signaling. The team also mentioned baricitinib’s potential for use in a combo therapy because it has little drug interaction with antiviral agents that are used as an alternative to Covid-19 treatment.

Richard Novak, head of infectious disease research with the University of Illinois at Chicago (UIC), is leading the U.S. trial on the combo of remdesivir and baricitinib. Novak expected that baricitinib’s anti-inflammatory effect would boost the impact of remdesivir in Covid-19.

The trial aims to recruit 800-1000 patients from 100 medical institutions around the world, including Korea. On May 18, the Seoul National University Hospital received the regulatory nod to join the study with 100 Covid-19 patients.

CytoDyn, a U.S. biotech firm, seeks to win U.S. FDA’s approval for a trial on adding HIV drug candidate leronlimab to remdesivir in Covid-19 treatment. Last year, the FDA granted fast-track status to leronlimab as a treatment for HIV. The company has completed a phase-3 study on the agent.

Leronlimab is an IgG4 monoclonal antibody that blocks CCR5, a cell receptor that causes HIV infection or tumor metastasis, according to CytoDyn. The agent is known to have both antiviral and anti-inflammatory effects.

Leronlimab showed therapeutic effects in 10 critically ill Covid-19 patients when used as emergency Investigational New Drug (eIND), the company said.

CytoDyn said it would prepare a phase-3 trial protocol on leronlimab to submit to the FDA for testing the agent with remdesivir.

The company will divide patients into three groups to compare the effects of leronlimab alone, remdesivir alone, and the combination of the two.

CytoDyn recently inked a deal with Samsung Biologics on the latter’s manufacturing of leronlimab.

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