Express Scripts covers Amgen, Lilly migraine therapies, excludes Teva drug
An Eli Lilly & Co. logo is seen on the cap of a pill bottle in this arranged photograph at a pharmacy in Princeton, Illinois.

Express Scripts , one of the largest U.S. prescription benefits managers, will cover new migraine drugs from Eli Lilly and Amgen , but is excluding a rival medication made by Teva Pharmaceutical after price negotiations with all three manufacturers.

The decision represents a setback for Teva, which is in the midst of a corporate restructuring and had hoped to capture a sizable stake of the multibillion-dollar migraine market. Express Scripts is also taking steps to limit use to the patients it says are most likely to benefit from the new Amgen and Lilly migraine drugs.

Pharmacy benefits managers like Express Scripts are taking more aggressive action to lower the cost of prescription drugs for their clients, large employers who pay for health benefits for their workers.

The new migraine drugs were approved for the U.S. market within a few months of each other this year. That gave Express Scripts more leverage in demanding a discount in exchange for putting a therapy on its "formulary," or list of covered drugs. "These products are fairly interchangeable," Harold Carter, clinical solutions director at Express Scripts, told Reuters. "It comes down to manufacturers providing the best value to be on the formulary." He acknowledged that price rebates played a role in determining coverage status, but declined to comment on the level of rebating.

In May, Amgen and marketing partner Novartis won U.S. regulatory approval for Aimovig, an injected drug designed to interfere with a process that helps kick off migraine headaches. Teva's Ajovy and Lilly's Emgality were approved last month. The three drugs work in a similar manner and represent an improvement over existing treatments: in clinical trials they significantly reduced migraine frequency in about half of patients.

Wei-Li Shao, vice president of neuroscience at Eli Lilly, told Reuters last month that discounts and rebates for the migraine drug would be negotiated with insurers and other payers. Brendan O'Grady, head of Teva's North America commercial operations, declined to comment on talks with payers, while executives at Amgen did not immediately respond to a request for comment.

All three drugs have a list price of $575 a month, or $6,900 a year. Geoffrey Porges, biotech analyst at Wall Street investment bank Leerink Partners, told Reuters he expects the drugmakers will need to offer rebates of at least 30 percent for the new migraine class to be covered by insurance.

Express Scripts already lists Amgen's Aimovig as a preferred treatment on its largest formulary, but requires that patients first try two older preventive therapies and a triptan, a family of generic drugs used to treat acute migraine. Lilly's Emgality will be covered under the same terms.

Amgen and Lilly will also begin next April to refund part of the drug cost if a migraine patient stops treatment within 90 days, indicating that the medication does not work for them or causes too many side effects. That refund, between 25 and 30 percent of the drugs' list price, would be returned to clients of Express Scripts, and comes in addition to the rebates the pharmacy benefit manager has already negotiated.

39 million migraine sufferers

"Everyone in the chain is taking some accountability for the cost of the drug," Carter said, adding that the refund means the manufacturers are sharing financial risk if the drugs do not work as well as claimed.

Around 39 million Americans suffer from migraine headaches, according to the Migraine Research Foundation. Worldwide migraine drug sales could reach $8.7 billion by 2026, according to analytics firm GlobalData.

But Carter estimated that only about 128,000 of the 83 million people who get their prescription drug benefits through Express Scripts will be good candidates for the migraine-prevention drugs. Under the Migraine Care Value program that will launch next April, Express Scripts will have its specially trained pharmacists, nurses and other staff assess appropriate care and access to therapies for patients.

The pharmacy benefit manager, which is being acquired by Cigna , created a similar program in 2015 that sharply limited the use of two novel, and expensive, cholesterol drugs — from Amgen and partners Regeneron Pharmaceuticals and Sanofi . For the new migraine drugs "the challenges will likely be right out of the gate, seeing if patients are responding to the therapy," Carter said.

The drugmakers have already tried to pre-empt efforts to limit access to the new migraine treatments. Amgen and Lilly are providing two months' supply of the drug for free directly to patients. All three companies have plans to pay nearly all of an individual's out of pocket costs under a commercial insurance plan. In addition, Amgen and Lilly have temporary programs to supply the treatments to patients who are covered by commercial insurance, but are still having trouble getting reimbursed.

Some large health insurers, such as Anthem , have similar coverage terms for Aimovig, requiring patients to document how they suffer from a defined number of headaches each month, and show that they have tried older migraine drugs first. Others, including Blue Cross/Blue Shield plans in states like Pennsylvania and Kansas, only cover prescriptions for the new drugs from — or in consultation with — a neurologist or headache specialist, and not a primary care doctor.

Some plans have not yet determined coverage terms, meaning each prescription has to go through a lengthy review process.