Mitsubishi's Medicago heads for the Covid-19 booster queue

With all the different variants in circulation, Covid-19 presents vaccines with a tougher challenge than in the early days of the pandemic. So headline efficacy of 71% from the phase 3 trial of Medicago’s project, announced today, feels like a respectable number.

There is a potential red flag here, however: the results released so far are on a per-protocol basis. The company insists that a “very similar” number was generated by an intent-to-treat analysis, a more rigorous test that regulators will presumably demand, and surpassed the 65% that the trial was powered to show.

Based on the number of events in each cohort, Evaluate Vantage calculates vaccine efficacy on an ITT basis as around 68%, which while less impressive still counts as a win. Meanwhile, efficacy rates against various variants, detailed in a press release and again on a per-protocol basis, also look good enough for approval – assuming that the results stand up to deeper scrutiny.

Medicago, a division of Mitsubishi Tanabe, told Vantage that around 14% of patients enrolled into the study were subsequently found to have evidence of a prior infection, adding that the cases were evenly distributed between the two cohorts.

Reassuringly, no severe cases or hospitalisations were seen with the vaccine, versus three and two cases respectively in the placebo group. No deaths due to Covid-19 were recorded.

Finding a role

Medicago has already begun a rolling submission with the Canada regulator, and initiated the filing process in the US and Europe. The group’s novel technology will also be scrutinised: it uses plants to generate the virus-like particles that form the basis of the vaccine (Mitsubishi's Medicago readies for the second wave, May 28, 2021).

Glaxosmithkline’s pandemic adjuvant is being used to boost the efficacy of this vaccine, although the pharma company's involvement in this project extends no further. 

Assuming that approvals are forthcoming, capacity is a big issue: for now, Medicago has pledged 76 million doses to the Canadian government, but that will be it until a new plant, capable of making a billion shots a year, comes online in 2024.

By that time, demand in more developed countries will be based mostly around boosters, and Medicago says it is planning a trial to test its shot in this setting.

Still, while MT-2766’s ultimate role in the pandemic remains unclear, this is notable progress for this developer. And it should not be forgotten that Medicago has beaten some considerably larger vaccine players to this result.