April 13 (Bloomberg) -- A patient taking Novartis AG’s Gilenya multiple sclerosis pill contracted a potentially deadly brain infection, adding to safety concerns about the Swiss drugmaker’s most promising potential blockbuster.
The patient used Tysabri, an injection from Biogen Idec Inc. and Elan Corp., before using Gilenya, Novartis said in an e-mailed statement today. Tysabri increases the risk of the viral infection, known as progressive multifocal leukoencephalopathy, that usually leads to death or severe disability, according to a warning the drug’s label has carried since 2006.
“The current assessment is that Tysabri is the drug most likely associated with this case of PML,” Novartis said in the statement. “However, a contribution of Gilenya to the evolution of this case cannot be excluded.”
“At this stage, we cannot comment on any role Gilenya might have had in this PML case,” an Elan spokeswoman said in an e-mail from Dublin.
“PML is an infrequent, but serious side effect in Tysabri-treated patients,” said Shannon Altimari, a Biogen spokeswoman, in an e-mail. “We cannot rule out the involvement of Gilenya as a contributing factor in this case.”
The case is the first of the infection among the 36,000 people treated with Gilenya since it was approved in 2010, which is reassuring because regulators are looking into unexplained deaths among Gilenya patients, according to analysts at Barclays Capital. The U.S. Food and Drug Administration and the European Medicines Agency are investigating 11 deaths of Gilenya patients.
The EMA said last month that it plans to announce the outcome of its review by April 20.
“I can’t say whether this will be considered in the frame of the ongoing review as the committee has been quite focused on the safety issue” raised earlier with the patient deaths, a spokeswoman for the London-based agency said by phone.
Worldwide sales of the type of MS medicines that include Gilenya and Tysabri, which suppress the immune system, exceeded $11 billion in 2010. Analysts predict that Gilenya will become Novartis’s third-best seller by 2015, reaching $2.06 billion in sales that year, according to the average of eight estimates compiled by Bloomberg.
“This could dampen Gilenya’s growth, especially in the frontline setting where the convenience of it being an oral therapy might not outweigh the risks in an increasing number of physician’s minds,” Michael Yee, an analyst with RBC Capital Markets in San Francisco, wrote in a note to clients today.
Novartis shares fell 0.3 percent to close at 49.85 Swiss francs in Zurich. The stock has dropped 7.2 percent this year.
“Clearly, this news comes at an inopportune time as the product continues to be under scrutiny,” Michael Leuchten, a London-based analyst for Barclays, wrote in a report today. Still, “the fact that this is the first case so far is hence encouraging and supports the Gilenya safety profile.”
Novartis said Dec. 12 that a U.S. patient died within 24 hours of starting treatment with Gilenya, triggering the regulator reviews, which reported a further 10 deaths among patients taking the medicine. Gilenya’s market share slipped in January for the first time after 15 months of growth since the drug’s introduction. Martin Voegtli, an analyst at Kepler Capital Markets SA in Zurich, in February cut his 2016 sales estimate by 12 percent to $1.96 billion.
Six of those 10 deaths were unexplained, three patients died of heart attacks and one due to disruption of heart rhythm, the EMA said Jan. 20. It isn’t clear whether the drug contributed to the deaths that regulators are reviewing, and the rate of fatalities is in line with the expected rate based on the number of patients who had been treated, Novartis said in January.
Regulators suspended Tysabri from the market in 2005 after some patients developed PML, then allowed its return in 2006 with a risk-management program for people who didn’t benefit from rival medicines. A revised Tysabri label now warns that patients who have antibodies against the so-called JC virus are more susceptible to developing PML. Biogen and Elan developed a blood test able to detect the antibodies in patients, which has eased safety concerns.
While the news might slow the uptake of Gilenya, it’s a positive development for Tysabri because doctors may hesitate to switch patients to Gilenya from Tysabri solely on safety concerns, Yee said.
“This case seems to suggest switching to Gilenya does not completely mitigate that risk,” he wrote.
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