Background and Overview

Tocilizumab is a monoclonal antibody (mAb) produced by Chugai Pharmaceutical and Roche that is commonly used for treating certain non-COVID-19 diseases, including rheumatoid arthritis; recently, it has also increasingly been used as a treatment for COVID-19.

Unlike several other mAb drugs used during the mild stages of COVID -19, tocilizumab is not used to target SARS-CoV2 (the virus that causes COVID-19). In other words, tocilizumab is not prescribed as a way to prevent the virus from infecting or multiplying within the cells of the body.

Instead, tocilizumab works against a particular chemical of your immune system, a cytokine called interleukin 6 (IL-6). IL-6 is a key cytokine in both the processes of inflammation and overactive inflammation - specifically in a COVID-19-related condition known as cytokine release syndrome (CRS).

CRS is one of the main abnormalities of COVID-19 that leads to a condition known as acute respiratory distress syndrome (ARDS), a life-threatening complication that often occurs in cases of severe COVID-19.

In most cases, ARDS leads to patients having to go onto mechanical ventilation, or to a more advanced system called extracorporeal membrane oxygenation (ECMO).

Engineered with a very specific three-dimensional shape, tocilizumab is designed to attach to IL-6, effectively reducing the intensity of CRS.

Effects of Tocilizumab on COVID-19

Clinical studies and clinical experience in using tocilizumab demonstrated reduced mortality (lower proportion of people dying) and a decreased need for mechanical ventilation - especially when given to patients whose COVID-19 has reached a high level of severity defined by a need for high-flow oxygen and the presence of fever (high-flow oxygen is supplemental oxygen that a patient receives in higher volumes over time than can be delivered through a simple tube in the nose or a simple face mask).

Appropriate Patients for Tocilizumab

While there are many considerations when determining who should receive tocilizumab, at is simplest, patients with COVID-19 who experience blood-oxygen saturation that cannot be raised to above 94 percent, even with a high amount of oxygen entering the lungs through a high flow oxygen device, may benefit from tocilizumab.

A patient diagnosed with severe COVID-19 would never receive tocilizumab as the only drug for treatment. These patients would also typically receive intravenous or oral corticosteroids (such as dexamethasone), an antiviral drug called remdesivir, medication that works against blood clotting, (especially low molecular weight heparin) and other medications as determined by his or her health care provider.

Tocilizumab: Pregnancy and Lactation Issues

There are very few data reflecting the use of tocilizumab for COVID-19 during pregnancy. However, experience with pregnant women receiving tocilizumab for rheumatological diseases (such as rheumatoid arthritis) suggests that the drug is fairly safe in pregnancy.

As for nursing mothers, tocilizumab appears to be safe for breastfeeding. As with other antibodies that are given intravenously (IV) or subcutaneously (SQ), the antibodies may pass from the mother’s blood to her milk but are not likely to be absorbed from the baby’s gastrointestinal tract into his or her blood.

How Tocilizumab is Administered

The preferred way to administer tocilizumab for COVID-19 is by intravenous (IV) infusion, usually over a period of 60 minutes. As an alternative, patients are sometimes able to receive subcutaneous (SQ) injection. Generally, just a single infusion is given, but some patients may receive a second infusion.

Limitations of Tocilizumab

The reduction in mortality and in the chance that a patient will need mechanical ventilation, when receiving tocilizumab, is not dramatic.

Side effects of tocilizumab generally include reactions at the site of infusion (pain, soreness, redness) as well as sore throat, runny or stuffy nose, sinus infection, headache, and increased blood pressure.

References

Jorgensen SCJ, Lapinsky SE. Tocilizumab for coronavirus disease 2019 in pregnancy and lactation: a narrative review. Clin Microbiol Infect. 2022 Jan;28(1):51-57. doi: 10.1016/j.cmi.2021.08.016. Epub 2021 Aug 23. PMID: 34438068; PMCID: PMC8381634.

National Institutes of Health. Coronavirus disease 2019 (COVID-19) treatment guidelines. Retrieved December 31, 2021

US Food and Drug Administration. Fact sheet for healthcare providers: emergency use authorization (EUA) of tocilizumab. Accessed December 31, 2021