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NIH Trials Testing Covid-19 Blood Clot Therapies

Heart, circulation system

(Bryan Brandenburg, Wikimedia Commons)

11 Sept. 2020. National Institutes of Health is starting two clinical trials testing a number of blood thinning treatments for people with blood clots from Covid-19 infections. The large-scale trials now or soon to be underway are assessing different anticoagulant treatments among patients hospitalized for Covid-19 infections or outpatients.

The clinical studies seek to identify most appropriate treatments for people developing life-threatening blood clots, an unusual complication from Covid-19 infections. These clots, which can occur even in small blood vessels, can lead to organ damage, stroke, heart attack, or blocked lung arteries. While no definitive mechanism is yet identified for blood clots occurring in some Covid-19 patients, says NIH, the danger posed to patients requires solutions be tested quickly.

“There is currently no standard of care for anticoagulation in hospitalized Covid-19 patients,” says NIH director Francis Collins in an agency statement, “and there is a desperate need for clinical evidence to guide practice.”

The trials are part of NIH’s Accelerating Covid-19 Therapeutic Interventions and Vaccines, or Activ, program to streamline and coordinate actions to combat the Covid-19 pandemic among agencies in the U.S. government, private pharmaceutical and biotech companies, international agencies, and not-for-profit groups. Among Activ’s goals is to accelerate evaluation of vaccine and therapy candidates to speed regulatory approval, including clinical trials of experimental drugs.

A clinical trial enrolling patients is testing the blood thinner heparin both as a treatment for blood clots and a step to prevent blood clots among hospitalized Covid-19 patients. The trial is enrolling 2,000 participants at sites with heavy Covid-19 infection rates, testing heparin doses at levels considered the standard of care for prevention of clots, then increasing heparin doses as treatments.

The study team is looking primarily at the need for additional support for patients’ lungs, as well as overall survival time, in the 21 days following treatment. The researchers are also tracking complications in the heart, kidneys, and stroke occurrence in patients, as well as safety issues, particularly major bleeding episodes and low platelet counts.

A second clinical trial, not yet recruiting participants, is testing anticoagulant drugs among 7,000 Covid-19 outpatients, those not requiring hospitalization. That study is testing the prescription blood thinner apixaban, at a low dose for preventing blood clots and a higher dose as a treatment, as well as aspirin, and a placebo.

The drugs will be sent to participants’ homes who will report electronically for 75 days on adherence and safety issues, such as major bleeding episodes.  The study team is looking mainly for participants’ hospitalization, for blood clots and other cardiovascular or respiratory events including heart attack and stroke in the 45 days following treatment.

A third clinical trial testing blood thinners among Covid-19 discharged from hospitals is not yet scheduled.

The trials use an adaptive design that allows for changing the course of the study while underway, without compromising gold-standard quality of the efficacy or safety data. Adaptive trials are usually governed by a single governing board and master protocol spelling out ground rules for the study, including standards and processes for assessing results, adding or closing sample groups, and adding new drugs or devices for testing. With these common rules, standards, and practices in place, adaptive trials make it possible to evaluate drugs and devices quicker, add new population groups to a study, or close treatment interventions if needed, even as data are being collected.

In addition, the Activ program uses existing networks of clinical trial sites to reduce start-up time for these studies. “Conducting trials using multiple existing networks of research sites,” notes Collins, “provides the scale and speed that will get us answers faster.”

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