AZ, J&J COVID-19 vaccine trials okay to restart in US

US trials of AstraZeneca’s experimental COVID-19 vaccine AZD1222 have been cleared to restart by the FDA, several weeks after testing was suspended following a serious adverse reaction in one patient who received the shot.

Separately, Johnson & Johnson has also announced it is resuming recruitment in a phase 3 trial of  its coronavirus candidate JNJ-78436735, which has also suspended after one study subject fell ill.

AZ confirmed the FDA’s move in a statement, saying that regulators in the US, UK, Brazil, South Africa and Japan have now said that trials of the Oxford University-partnered shot are safe to continue.

The FDA took a lot longer to reach its conclusion however, as recruitment into studies restarted just a few days after the halt elsewhere.

AZ chief executive Pascal Soriot said: “We should be reassured by the care taken by independent regulators to protect the public and ensure the vaccine is safe before it is approved for use.”

On 6 September, AZ said it had put trials of AZD1222 on temporary hold because of a potential safety issue involving one patient in the UK, who had become ill after taking the vaccine with what at the time was reported to be transverse myelitis – an inflammation of the spinal cord that can be associated with viral infections as well as neurological conditions like multiple sclerosis.

“It is not unusual that in large scale vaccine trials, some participants will become unwell, and every case has to be evaluated to ensure the careful assessment of safety,” said AZ, which hasn’t confirmed the nature of the adverse reaction.

A report in the Wall Street Journal suggests that the FDA has reviewed two cases of potential neurological side effects in patients receiving AZD1222. One was subsequently found to be in a patient with MS, but the US regulator couldn’t either identify or rule out a clear link to the vaccine in both cases.

A death has also occurred in a patient enrolled onto an AZD1222 study in Brazil, although that has not been linked to the vaccine and is believed to have occurred in a subject who did not receive the shot.

AZ is now expecting to have results from the trials before the end of the year – analysts at Jefferies think it could occur in mid-November – and rolling regulatory  reviews of AZD1222 are already underway in some markets including the EU.

J&J meanwhile said that the independent data safety monitoring committee overseeing the phase 3 ENSEMBLE trial of JNJ-78436735 had found no clear cause behind a “serious medical event” – reported to be a stoke – in one subject that caused the study to be placed on hold earlier this month.

“After a thorough evaluation of a serious medical event experienced by one study participant, no clear cause has been identified,” said the drugmaker in a statement indicating the findings had been shared with the FDA. “There are many possible factors that could have caused the event.”

The suspension of studies for AZD1222 and JNJ-78436735 has put two coronavirus vaccines from BioNTech/Pfizer and Moderna in the lead in the US, with top-line efficacy results due within the next 4-5 weeks, although safety data will take a little longer to come in.

The resumption of the two stalled studies means that AZ and J&J will now not be too far behind.