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Here's Why PTC Therapeutics Is Soaring While Biogen and Ionis Struggle

Brian Orelli, The Motley Fool

What happened

Shares of PTC Therapeutics (NASDAQ: PTCT) are up 24.6% at 12:40 p.m. EDT after PTC and partner Roche (NASDAQOTH: RHHBY) presented data on their spinal muscular atrophy (SMA) drug, risdiplam, at the 22nd Annual SMA Researcher Meeting.

Likewise, Biogen (NASDAQ: BIIB) and Ionis Pharmaceuticals (NASDAQ: IONS), which have the only SMA drug on the market, are feeling the heat from the promising data with shares down 5.6% and 7.3%, respectively.

Doctor examining a baby's foot

Image source: Getty Images.

So what

The 182-day update for PTC and Roche's FIREFISH study showed the treatment raised the median Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score by 14 points compared to the start of the study. The latest update is an improvement on the 12.5-point increase at day 119 and a 5.5-point jump at day 56.

Just as importantly, 91% of the babies had an increase of four points or more in their CHOP-INTEND score, suggesting the drug is helping almost all the patients, at least a little.

The day 119 data only comes from 11 babies, but is impressive nonetheless since this is a progressive disease. By comparison, Biogen and Ionis Pharmaceuticals' Spinraza produced at least a four-point improvement in CHOP-INTEND in 63% of the 52 babies tested at day 183.

Risdiplam also has a potential advantage over Spinraza in that it can be taken orally while Spinraza has to be injected into the spine. As bad as an injection into the spine sounds, Spinraza only has to be administered four times a year, while giving medication to a baby daily could be challenging.

Now what

The second part of the FIREFISH study, which should be enough to gain Food and Drug Administration approval in enrolling patients. The primary endpoint of the study is measured after 12 months, so any potential competition for Biogen and Ionis is still a few years away. Nevertheless, PTC and Roche appear to have a promising drug that can compete if the data holds up in a larger data set.

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Brian Orelli has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Biogen and Ionis Pharmaceuticals. The Motley Fool has a disclosure policy.