The risk of expansion is overblown, IMO. This comes down entirely to the fact that Cynata are targeting HIGH-RISK aGvHD, while Ryoncil and Ruxo are for STEROID REFRACTORY aGvHD. The condition isn't classified as SR until at least 72 hours of no response or worsening of symptoms after the administration of steroids.
Ruxo got a label extension for cGvHD on the back of results from a trial that demonstrated some efficacy, but a nasty safety profile:
https://www.nejm.org/doi/full/10.1056/NEJMoa2033122Given the nature of the harsh side effects it has on recipients, I don't think the FDA would dare grant a label extension for HR-aGvHD. At the HR stage, you would risk giving a poor quality of life to people who otherwise don't need it. It would be the equivalent of every person with a tumour receiving chemo and radio therapy - it's just not necessary in some circumstances. But for people who already have a high mortality rate, it isn't that difficult to see why approval was granted for SR-cGvHD.
Regarding Meso, will they get an expansion into SR-aGvHD in adults? Maybe - but again they're still not competing with Cynata, as they are treatments administered at different time points. As an example, in Cynata's Phase 2 trial, patients could technically receive CYP-001, not respond or get worse, then receive Ruxolitinib. In addition, there are also quite a few adverse reactions identified from Mesoblast's clinical trial including:
"infections, fever, hemorrhage, edema, abdominal pain and hypertension." I doubt the FDA would grant a label extension to HR given the prevalence of these issues.
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