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

The Canadian subsidiary claims success in its pivotal trial, though capacity restraints will limit the jab’s role for now.

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.

Plant power: topline results from Medicago's Covid-19 vaccine 
    Covid-19 events  
  Efficacy Vaccine Placebo
Topline analyses
Per protocol 71% 39 118
Intent to treat 68%* 40 125
Subgroups (per protocol)
Those with no prior Covid-19 exposure  75.6%    
Delta variant  75.3%    
Gamma variant 88.6%    
Note: *calculated by Evaluate Vantage, assuming enrolment of 12,000 patients into each cohort; all other data sourced to Medicago.

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.

Aiming for the booster market? the second wave of Covid-19 vaccines 
Company Project Mechanism/technology  Status Trial
Medicago (Mitsubishi; uses Glaxosmithkline adjuvant)
MT-2766  Plant based, virus-like particle vaccine Topline VE 71% (Dec 2021); rolling review ongoing in Canada, filings in US, Europe and globally to follow NCT04636697
Novavax NVX-CoV2373  Recombinant spike protein vaccine Topline VE 91% (Jun 2021); filed in Europe and other international markets; US filing due before YE 2021 NCT04583995
Valneva VLA2001 Adjuvanted, inactivated virus  Succeeded in ph3 Cov-Compare vs Vaxzevria*; filed with EMA and MHRA NCT04864561
Unnamed vaccine Monovalent and bivalent recombinant protein vaccines Efficacy readout due by YE 2021 NCT04904549
INO-4800/ VGX-3100 DNA vaccine Ph3 Innovate trial ongoing in S America & Asia; FDA clinical hold lifted Nov 2021; interim efficacy data due H1 2022 NCT04642638
Bavarian Nordic  ABNCoV2 Capsid virus-like particle vaccine Pivotal trial to start in 2022, probably a non-inferiority study in booster setting vs approved mRNA vaccine TBC
Arcturus  ARCT-021  mRNA vaccine Ph2 fully enrolled; selected for ph3 by an unnamed "global entity" NCT04668339
ARCT-154 mRNA vaccine  Pivotal development ongoing in Vietnam with partner Vinbiotech, filing expected by YE 2021; ph2 US booster study results due Q1 2022 NCT05012943; NCT05037097
Vaxart VXA-CoV2-1  Oral vaccine Ph2 started in US Q3 2021, results due Q1 2022 NCT05067933
*No ph3 placebo-controlled study has been conducted with VLA2001. In Cov-Compare the project showed significantly higher levels of neutralising antibodies than Astra’s vaccine, and similar rates of seroconversion. Source: Evaluate Pharma &

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