Johnson & Johnson confirmed that it paused further dosing in all clinical studies of its COVID-19 vaccine candidate JNJ-78436735, including the phase 3 ENSEMBLE trial, due to an “unexplained illness” in a participant. The company noted that the subject’s illness is being reviewed and evaluated by the ENSEMBLE independent data safety monitoring board (DSMB), as well as its own internal clinical and safety physicians.
According to Johnson & Johnson, all clinical studies it conducts have prespecified guidelines allowing them to be paused if an unexpected serious adverse event that might be related to a vaccine or a drug is reported. The company added “we’re…learning more about this participant’s illness, and it’s important to have all the facts before we share additional information.” The drugmaker also noted that “as many trials are placebo-controlled, it is not always immediately apparent whether a participant received a study treatment or a placebo.”
Johnson & Johnson’s ENSEMBLE study started last month and is designed to enroll up to 60,000 volunteers to evaluate the safety and efficacy of a single vaccine dose versus placebo in preventing COVID-19. At the time, chief scientific officer Paul Stoffels suggested that results of the trial are expected by year end or early in 2021.
Second vaccine to face late-stage safety issue
The pause of the ENSEMBLE study comes just over a month after AstraZeneca confirmed that a phase 3 trial of its experimental COVID-19 vaccine AZD1222 was put on hold due to a possible safety issue, believed to be a case of transverse myelitis in one subject. Studies of the vaccine were cleared to resume shortly afterwards by regulators including those in the UK, Brazil, South Africa and India, and more recently in Japan. However, trials in the US remain on hold as the FDA continues its review of the serious adverse event.
Commenting on the ENSEMBLE pause, Hassan Vally, an associate professor in epidemiology at La Trobe University in Melbourne, said “we’re going to have to get used to hearing these sorts of reports.” Vally noted “as you vaccinate more people in these trials the chances are that there will be some illnesses in participants. The only difference here is that in the world that we live in right now, the progress of these trials are in the public eye.”
Likely a neurological event, analyst says
Meanwhile, William Schaffner, a professor of infectious diseases at the Vanderbilt University School of Medicine, remarked “everybody is on the alert because of what happened with AstraZeneca.” Schaffner suggested that the safety issue from the ENSEMBLE study “is likely to be a neurological event,” adding it could take a week to gather information.
Further, Bryan Garnier analyst Olga Smolentseva commented “this could be a second case of adenoviral vaccine to spur safety concerns.” JNJ-78436735 utilises Johnson & Johnson’s AdVac technology, which is based on the development and production of adenovirus vectors, while AZD1222 uses a chimpanzee adenovirus vector.
Separately on Tuesday, Johnson & Johnson reported its third-quarter financial results, with the company boosting its full-year guidance.