Roche's SMA drug risdiplam hits targets in children ahead of FDA decision

It’s not far off crunch time for Roche’s potential spinal muscular atrophy (SMA) drug, risdiplam, which the big Swiss pharma hopes will generate blockbuster revenues as well as taking market share from its rivals Novartis and Biogen.

With the FDA due to make a decision on or before 24th May, Roche has just released data from part 2 of the pivotal SUNFISH trial, in people aged 2-25 years with type 2 or 3 SMA.

Roche published supportive results from part 1 of the trial involving infants in May last year, and this latest set of results from patients aged 2-25 helps to complete the picture of the drug’s performance in the deadly muscle-wasting disease.

Risdiplam will be up against Biogen’s antisense drug Spinraza, which has been on the market since 2016, and Novartis’ gene therapy Zolgensma.

Both are extremely expensive – Biogen’s drug costs $750,000 for the first year of treatment and around $375,000 annually thereafter, while Novartis’ one-off gene therapy is the world’s most expensive drug at $2.1 million a shot.

In contrast risdiplam is an orally administered liquid that could provide an alternative to these, and although the Swiss pharma will charge a premium price, a strong set of clinical results will help make its case with cost-conscious payers.

The data presented by Roche today from the 180-patient trial showed from baseline in the primary endpoint of the Motor Function Measure scale (MFM-32) was significantly greater in people treated with risdiplam, compared to placebo, a 1.55 point mean difference after a year of treatment.

The Revised Upper Limb Module, an important secondary goal, showed a significant improvement of 1.59 points.

Safety-wise there were no new surprises, and as anticipated an exploratory analysis showed the strongest responses were seen in children aged two to five years.

In this group 78% saw an increase of at least three points, compared with 53% taking a placebo.

Disease stabilisation was seen in the 18-25 years age group, with 57% showing no worsening of their condition compared with 37.5% on placebo.