* Novartis says baby's death not caused by Zolgensma
* Underlying cause seen as brain damage, respiratory infection
* New data underscores importance of early SMA treatment
By John Miller
ZURICH, Sept 19 (Reuters) - A British baby's death this year after getting Novartis's gene therapy Zolgensma was not caused by a toxic drug reaction, the Swiss drugmaker said, allaying concerns over the $2.1 million-per-patient treatment's risks.
Novartis also said on Thursday that babies with muscle-wasting spinal muscular atrophy (SMA) treated before symptoms emerge were meeting normal development milestones, a welcome announcement amid revelations of data manipulation that have shrouded Zolgensma.
Novartis has been investigating the death of a 6-month-old patient in a European trial. Novartis executives now say investigators and the coroner concluded the immediate cause was brain damage from oxygen deprivation after respiratory distress, not brain damage from a toxic drug agent.
"There was no evidence of any inflammatory central nervous system process or toxic or drug-related brain damage," said Olga Santiago, chief medical officer of Novartis's gene therapy unit AveXis, on a call with reporters.
While gene therapy may have contributed to some of the reasons why the baby was hospitalised in London, such as abnormal liver function and low blood pressure, Novartis said those are side effects it has long known about.
"We had been concerned about the potential... that Zolgensma might have been causing brain inflammation," said AveXis Chief Executive Dave Lennon. "In this case, the original diagnosis, and that association, hasn't held true."
Zolgensma, the world's most expensive one-time medical treatment, has provided hope for families facing a devastating diagnosis of SMA, the leading genetic cause of infant death.
It has also made negative headlines: in August, the U.S. Food and Drug Administration began probing manipulation of early data by AveXis scientists, saying it could result in criminal or civil action.
While Novartis replaced AveXis employees and has since promised to speed disclosures of problematic data, the FDA left Zolgensma on the market after concluding it is safe and effective.
Study data released by Novartis on Thursday at the European Paediatric Neurology Society Congress in Greece appear to underscore the FDA's decision, particularly for babies tested for SMA at birth and who receive treatment before showing floppy muscles and other symptoms.
Among 10 patients measured so far in Novartis's SPRINT study, none was delayed in unsupported sitting. Six could sit at an average of 7.6 months, while three stood with assistance at an average 10.1 months.
Without treatment, they faced death or permanent breathing help.
Like a previous study in kids treated before symptoms emerge with the first approved SMA treatment, Biogen's $750,000 Spinraza, Novartis's results underscore newborn screening's importance in helping children achieve the best outcomes, Santiago said. [reut.rs/2kmuH6H ]
Kids treated with Spinraza or Zolgensma after SMA symptoms emerge often survive, but may never stand and face a lifetime of costly medical challenges. While U.S. states are adding newborn SMA screening, Novartis said Europe is lagging.
"It's critical to diagnose early and to begin treatment as early as possible to stop the irreversible motor neuron loss, and make the achievement of motor milestones such as crawling, sitting and walking possible," Santiago said. (Reporting by John Miller; Editing by Michael Shields)