@Southoz you wrote
"The 2:1 randomisation allocation means a participant has 2 chances in 3 of receiving the intervention compared to 1 chance in 3 of receiving the placebo. Good odds for the participant but a less efficient design than 1:1 allocation."
There are practical reasons for the 2:1 randomisation.
The reason 2 out of 3 participants get a treatment is there are 3 arms to the trial;
"This is a prospective, multicenter, randomized, double-blind, placebo-controlled Phase 3 study designed to evaluate the safety and efficacy of Mesoblast's rexlemestrocel-L alone or combined with hyaluronic acid (HA) in subjects with chronic low back pain (> 6 months) associated with moderate radiographic degenerative changes of a disc"
Experimental: rexlemestrocel-Lrexlemestrocel-L alone": 2.0 mL formulation of approximately 6 million rexlemestrocel-L cells
Drug: rexlemestrocel-Lrexlemestrocel-L alone": 2.0 mL formulation of approximately 6 million rexlemestrocel-L cells - Intervention will be injected into the painful intervertebral disc
Drug: rexlemestrocel-L + HArexlemestrocel-L + HA": 2.0mL 6 million rexlemestrocel-L cells with 1% HA - Intervention will be injected into the painful intervertebral disc
3
Placebo Comparator: Placebosaline control: 2.0 mL saline solution
Drug: Placebosaline control: 2.0 mL saline solution
In the earlier trial if I recall correctly the HA (Hyaluronic Acid) was trialed alone, as one of the arms, not with rexlemestrocel-L, this time it is included with rexlemestrocel-L.
A web search should provide clues as to why Hyaluronic Acid has been included with the rexlemestrocel-L. Hopefully it will improve the responses recorded from the last trial, in terms of speed and effect, perhaps there other outcomes desired as well.
(20min delay)