Tocilizumab Stumbles as COVID-19 Treatment, Narrow Role Possible

Laird Harrison

October 28, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Tocilizumab (Actemra/RoActemra) was not found to have any clear role as a treatment for COVID-19 in four new studies.

Three randomized controlled trials showed that the drug either had no benefit or only a modest one, contradicting a large retrospective study that had hinted at a more robust effect.

"This is not a blockbuster," said David Cennimo, MD, an infectious disease expert at Rutgers New Jersey Medical School, Newark, New Jersey. "This is not something that's going to revolutionize our treatment of COVID-19."

But some researchers still regard these studies as showing evidence that the drug benefits certain patients with severe inflammation.

The immune response to SARS-CoV-2 includes elevated levels of the cytokine interleukin-6 (IL-6). In some patients, this response becomes a nonspecific inflammation, a "cytokine storm," involving edema and inflammatory cell infiltration in the lungs. These cases are among the most severe.

Dexamethasone has proved effective in controlling this inflammation in some patients. Researchers have theorized that a more targeted suppression of IL-6 could be even more effective or work in cases that don't respond to dexamethasone.

A recombinant monoclonal antibody, tocilizumab blocks IL-6 receptors. It is approved by the US Food and Drug Administration for use in patients with rheumatologic disorders and cytokine release syndrome induced by chimeric antigen receptor T-cell therapy.

Current National Institutes of Health (NIH) guidelines recommend against the use of tocilizumab as a treatment for COVID-19, despite earlier observational studies that suggested the drug might help patients with moderate to severe disease. Controlled trials were lacking until now.

The most hopeful results in this batch came from the CORIMUNO-19 platform of open-label, randomized controlled trials of immune modulatory treatments for moderate or severe COVID-19 in France.

Published in JAMA Internal Medicine , the trial recruited patients from nine French hospitals. Patients were eligible if they required at least 3 L/min of oxygen without ventilation or admission to the intensive care unit.

The investigators randomly assigned 64 patients to receive tocilizumab 8 mg/kg body weight intravenously plus usual care and 67 patients to usual care alone. Usual care included antibiotic agents, antiviral agents, corticosteroids, vasopressor support, and anticoagulants.

After 4 days, the investigators scored patients on the World Health Organization 10-point Clinical Progression Scale. Twelve of the patients who received tocilizumab scored higher than 5, vs 19 of the patients in the usual care group, with higher scores indicating clinical deterioration.

After 14 days, 24% of the patients taking tocilizumab required either noninvasive ventilation or mechanical ventilation or had died, vs 36% in the usual care group (median posterior hazard ratio [HR], 0.58; 90% credible interval, 0.33 – 1.00).

"We reduced the risk of dying or requiring mechanical ventilation, so for me, the study was positive," said Olivier Hermine, MD, PhD, a professor of hematology at Paris Descartes University in Paris, France.

However, there was no difference in mortality at 28 days. Hermine hopes to have longer-term outcomes soon, he told Medscape Medical News.

A second randomized controlled trial, also published in JAMA Internal Medicine , provided less hope. In this RCT-TCZ-COVID-19 Study Group trial, conducted at 24 Italian centers, patients were enrolled if their partial pressure of arterial oxygen to fraction of inspired oxygen (Pao2/Fio2) ratios were between 200 and 300 mmHg and if their inflammatory phenotypes were defined by fever and elevated C-reactive protein level.

The investigators randomly assigned 60 patients to receive tocilizumab 8 mg/kg up to a maximum of 800 mg within 8 hours of randomization, followed by a second dose after 12 hours. They assigned 66 patients to a control group that received supportive care until clinical worsening, at which point patients could receive tocilizumab as a rescue therapy.

Of the patients who received tocilizumab, 28.3% showed clinical worsening within 14 days, compared to 27.0% in the control group (rate ratio, 1.05; 95% CI, 0.59 – 1.86). There was no significant difference between the groups in terms of the proportion admitted to intensive care. The researchers stopped the trial prematurely because tocilizumab did not seem to be making a difference.

The BACC Bay Tocilizumab Trial was conducted at seven Boston hospitals. The results, which were published in The New England Journal of Medicine, were also discouraging.

In that trial, enrolled patients met two sets of parameters. First, the patients had at least one of the following signs: C-reactive protein level higher than 50 mg/L, ferritin level higher than 500 ng/mL, d-dimer level higher than 1000 ng/mL, or a lactate dehydrogenase level higher than 250 U/L. Second, the patients had to have at least two of the following signs: body temperature >38° C, pulmonary infiltrates, or the need for supplemental oxygen to maintain an oxygen saturation greater than 92%.

The investigators randomly assigned 161 patients to receive intravenous tocilizumab 8 mg/kg up to 800 mg and 81 to receive a placebo.

They didn't find a statistically significant difference between the groups. The hazard ratio for intubation or death in the tocilizumab group as compared with the placebo group was 0.83 (95% CI, 0.38 – 1.81; P = .64). The hazard ratio for disease worsening was 1.11 (95% CI, 0.59 – 2.10; P = .73). At 14 days, the conditions of 18.0% of the patients who received tocilizumab and 14.9% of the patients who received the placebo worsened.

In contrast to these randomized trials, STOP-COVID, a retrospective analysis of 3924 patients, also published in JAMA Internal Medicine, found that the risk for death was lower for patients treated with tocilizumab compared with those not treated with tocilizumab (hazard ratio [HR], 0.71; 95% CI, 0.56 – 0.92) over a median follow-up period of 27 days.

Also on the bright side, none of the new studies showed significant adverse reactions to tocilizumab.

More randomized clinical trials are underway. In press releases announcing topline data, Roche reported mostly negative results in its phase 3 COVACTA trial but noted a 44% reduction in the risk for progression to death or ventilation in its phase 3 IMPACTA trial. Roche did not comment on the ethnicity of its COVACTA patients; it said IMPACTA enrolled a majority of Hispanic patients and included large representations of Native American and Black patients.

Results Don't Support Routine Use

Commenting on the new studies, editorialists in both JAMA Internal Medicine and The New England Journal of Medicine concluded that the tocilizumab results were not strong enough to support routine use.

"My take home-point from looking at all of these together is that even if it does help, it's most likely in a small subset of the population and/or a small effect," Cennimo told Medscape Medical News.

But the NIH recommendation against tocilizumab goes too far, argued Cristina Mussini, MD, a professor of infectious diseases at the University of Modena and Reggio Emilia in Italy, who is a coauthor of a cohort study of tocilizumab and served on the CORIMUNO-19 Data Safety and Monitoring Board.

"I really think it's too early to recommend against it because at least two clinical trials showed protection against mechanical ventilation and death," she said.

She prescribes tocilizumab for patients who have not been helped by dexamethasone. "It's just a rescue drug," she told Medscape Medical News. "It's not something you use for everybody, but it's the only weapon we have now when the patient is really going to the intensive care unit."

The BACC Bay Tocilizumab Trial was funded by Genentech/Roche. Genentech/Roche provided the drug for the CORIMUNO and RCT-TCZ-COVID-19 trials. The STOP-COVID study was supported by grants from the NIH and by the Frankel Cardiovascular Center COVID-19: Impact Research Ignitor. Cennimo, Hermine, and Mussini have disclosed no relevant financial relationships.

JAMA Intern Med. Published online October 20, 2020. CORIMUNO-19 trial, Full text; RCT-TCZ-COVID-19 Study Group trial, Full text; STOP-COVID analysis, Full text; Editorial

N Engl J Med. Published online October 21. BACC Bay Tocilizumab Trial, Full text

Laird Harrison writes about science, health and culture. His work has appeared in national magazines, in newspapers, on public radio and on websites. He is at work on a novel about alternate realities in physics. Harrison teaches writing at the Writers Grotto. Visit him at lairdharrison.com or follow him on Twitter: @LairdH.

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