I-Mab’s experimental COVID-19 treatment reduced the mechanical ventilation rate in patients, putting the Chinese biotech in the game with Humanigen in trying to improve treatment options for the sickest patients.
The ongoing phase 2/3 study is testing I-Mab’s plonmarlimab for the treatment of cytokine release syndrome, an over-active immune response associated with a higher death rate in COVID-19 patients.
Currently, physicians treat such severe patients with steroids and Gilead’s remdesivir, but there remains a need for more efficacious therapies, especially as the new Delta variant grips the U.S. and the world, bumping up hospitalizations once again.
I-Mab’s therapy targets a certain cytokine that plays a critical role in acute and chronic inflammation. The study’s main goal is to examine plonmarlimab’s safety, efficacy and effect on cytokine levels in patients with severe COVID-19.
Plonmarlimab, or TJM2, improved the rate of mechanical ventilation free treatment compared to placebo, at a rate of 83.6% vs 76.7% by day 30. The therapy was also associated with a lower mortality rate of 4.9% vs 13.3% and higher recovery rates. I-Mab also said the therapy reduced recovery time and hospitalization duration.
There’s a lot to unpack there, and the details were short in I-Mab’s statement. Many of the improvement percentages compared to placebo are not too far off—but they could be significant to these very sick patients who have few other options.
I-Mab threw down the gauntlet against Humanigen, which has a COVID-19 therapeutic already under review in the U.S. and U.K. Lenzilumab also tries to stop cytokine storms.
“The magnitudes of the clinical improvements are comparable to those observed with lenzilumab in a similar patient population,” I-Mab said.
Humanigen has estimated that lenzilumab caused 37% more recoveries than standard of care in hospitalized COVID-19 patients in a phase 3 trial.
The study has an adaptive trial design, meaning patients can only stay enrolled if the interim analysis shows an average improvement in recoveries of 29% or more. The improvement rate was calculated based on enrollment requested by the data safety monitoring board.
Whether the two therapies can be compared apples to apples remains to be seen, as they are not examining the exact same outcome. But improvement is improvement when a patient has severe COVID-19, and drug regulators are scrambling to incentivize the development of more effective treatments.
Analysts have predicted that Humanigen's drug could become the standard of care for the sickest hospitalized COVID-19 patients and bring in $1 billion in sales in the first 12 months after approval. GlaxoSmithKline is also investigating a cytokine release drug.