Shares in PTC Therapeutics' rise on preliminary data from spinal muscular atrophy treatment partnered with Roche

Shares in PTC Therapeutics jumped as much as nearly 40 percent Monday after the company presented updated interim results at the annual SMA Researcher Meeting from the first part of the FIREFISH study investigating risdiplam in babies with Type 1 spinal muscular atrophy (SMA). PTC is developing risdiplam, also known as RG7916, in collaboration with Roche and the SMA Foundation under the terms of a 2011 partnership

The first part of the FIREFISH trial examined the safety of risdiplam in 21 infants and determined the dose for the next phase. Part two of the pivotal study, which is ongoing, will evaluate the selected risdiplam dose in about 40 infants with Type 1 SMA for 24 months.

According to PTC, the updated interim results showed that at day 182, over 90 percent of the babies achieved a greater than 4-point increase compared to baseline in the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score, designed to measure motor milestone development of patients with SMA Type 1. PTC chief executive Stuart Peltz commented "we are delighted that up to 6.5-fold increase of protein production has translated into clinical impact for these babies." 

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The company noted that median increases in CHOP-INTEND scores were 5.5 points at day 56, 12.5 points at day 119, and 14 points at day 182 of treatment. Further, risdiplam was "well tolerated at all dose levels and to date there have been no drug-related safety findings leading to withdrawal," PTC said, adding that "no babies have required a tracheostomy or permanent ventilation since study initiation and no baby has lost the ability to swallow." 

Commenting on the news, Barclays analyst Emmanuel Papadakis suggested that risdiplam could become a major competitor to Biogen's Spinraza (nusinersen), currently the only licensed SMA therapy, while analysts at Cowen & Co. also said the update is encouraging for approval, noting that PTC's therapy is an oral formulation, while Spinraza is injected into the spine. 

Spinraza, which is partnered with Ionis Pharmaceuticals, is approved in the US and in Europe for the treatment of SMA in children and adults. Biogen has priced the treatment in the US at $750 000 per patient for the first year, with the cost falling to $375 000 thereafter. Meanwhile, Novartis reached an agreement in April to purchase AveXis for $8.7 billion, gaining rights to the investigational SMA treatment AVXS-101. 

For related analysis, see ViewPoints: Spinraza's new threat may be more real and more present.

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