PERTH, Australia – Australian stem cell company Mesoblast Ltd.’s shares were up nearly 39% on the news that its allogeneic cell therapy showed an 83% survival rate in ventilator-dependent COVID-19 patients with moderate to severe acute respiratory distress syndrome (ARDS) treated at New York’s Mount Sinai Hospital.

Nine of the 12 treated patients (75%) have successfully come off ventilator support within 10 days following two infusions of remestemcel-L.

“Once you’re ventilated when you have acute respiratory distress syndrome in the lungs, your likelihood of coming off a ventilator is 9%, and your survival is 12%,” Mesoblast CEO Silviu Itescu told BioWorld.

In contrast, only 9%, or 38 of 445 ventilator-dependent COVID-19 patients at a major hospital network in New York were able to come off ventilator support when treated with standard of care during the same March to April period.

Moreover, there was 88% mortality with only 12% survival (38/320) among ventilator-dependent COVID-19 patients at a second major hospital network in New York during the same period.

Those poor outcomes are consistent with earlier published data from China where mortality rates of over 80% were reported in patients with COVID-19 and moderate to severe ARDS.

At this time, seven of the 12 treated patients have been discharged from the hospital. Patients received a variety of experimental agents prior to remestemcel-L. All patients were treated under an emergency IND or expanded access protocol at Mount Sinai.

Under the protocol, patients come into intensive care and received standard-of-care treatment. Once they were intubated on a ventilator, they were treated within 72 hours with two infusions of Mesoblast’s remestemcel-L cells within five days.

A bright light among dismal options

“What’s exciting is that our patients in the same epicenter of this disease with the same treatment everyone else is getting, suddenly 75% are coming off of ventilators within 10 days, and we’ve got 83% survival,” Itescu said.

Silviu Itescu, CEO, Mesoblast

“At the same time, the kind of drugs that are being touted by big pharma are gone. You have hydroxychloroquine that every man and his dog were talking about, and that came out in a randomized controlled trial and it failed, and maybe it’s killing people.

“And today you saw Gilead’s drug remdesivir, and the first randomized controlled trial failed, and that’s in easy-to-treat patients with very mild lung disease,” Itescu added.

“We’re tackling the hardest of the hard, which these pharma companies have got nothing for, and we’re getting these survival outcomes.”

The compassionate use treatment experience has informed the design of the clinical protocol for a randomized, placebo-controlled phase II/III trial of remestemcel-L in ventilator-dependent COVID-19 moderate to severe ARDS patients across North America.

The FDA has approved the same protocol for the phase II/III trial, and it will be powered so that results will be “self-evident,” Itescu said, noting that the trial will begin “imminently” in 20 to 30 sites across the U.S..

“We’ll know very fast if we’re seeing the same survival benefit in a randomized trial,” the CEO said.

“What people are dying of is acute respiratory distress syndrome, which is the body’s immune response to the virus in the lungs, and the immune system goes haywire, and in its battle with the virus it overreacts and causes severe damage to the lungs,” he said.

Mesoblast's allogeneic candidates are based on mesenchymal lineage cells collected from the bone marrow of healthy adult donors.

The stem cell therapy is currently being reviewed by the FDA for potential approval in the treatment of children with steroid-refractory acute graft-vs.-host disease (aGVHD). The company submitted the final module of a rolling BLA in January 2020. The FDA has set a PDUFA date of Sept. 30 for the product branded as Ryoncil.

The clinical data submitted with the BLA showed a survival rate of 79% compared to an expected 30% survival rate in the pediatric phase III trial in aGVHD.

“Up to now we’ve been focused on GVHD, so we’ll need to ramp up manufacturing,” the CEO said, adding that he is in active partnering discussions.

“We’ve worked very hard in the last six weeks to see that it actually works [in COVID-19]. We put all the building blocks in place, and when the opportunity comes up, we can move along quickly.”

Headquartered in Melbourne, Mesoblast also has facilities in New York, Singapore and Texas. It is listed on the Australian Securities Exchange (ASX:MSB), where its shares were up 38.9% on the news, trading at AU$2.73 per share by market close April 24.

On Nasdaq, the jump was even more impressive, with shares gaining 139.5% April 24 to end the day at $15.45.