Fresh off the historic but controversial U.S. approval of its Alzheimer’s drug Aduhelm made in a tie-up with Biogen Inc., Japanese pharmaceutical company Eisai Co. says it’s pushing ahead with its second therapy to combat the disease — which has shown fewer side effects and could come in a more convenient form for patients.

The Tokyo-based company is pressing ahead with its second drug amid ongoing scrutiny around the U.S. Food and Drug Administration’s June approval of Aduhelm, which caused resignations among a panel of independent experts who said the therapy was ineffective and has also prompted a call for a federal probe.

Eisai’s second compound in development to treat Alzheimer’s has the potential for fewer side effects like brain swelling and bleeding, and could come in an injection enabling at-home administration rather than intravenous infusions in hospitals, Ivan Cheung, the New Jersey-based global president of Eisai’s neurology business, said in an interview last week. The second drug, known as lecanemab or BAN2401, works similarly to Aduhelm by reducing amyloid plaques from the brains of Alzheimer’s patients.

"That kind of efficacy, safety balance should be quite interesting for lecanemab,” Cheung said.

Lecanemab received a breakthrough therapy designation from the FDA last month, in a decision that’s intended to speed up the review of drugs that treat life threatening ailments but doesn’t mean the regulator has determined they will be approved.

Eisai will meet with FDA regulators before deciding how to approach seeking approval for lecanemab, Cheung said, though he declined to give a time frame on when that would take place.

The stakes are high for Eisai, which has devoted over 30 years to Alzheimer’s and dementia-related research. Its drug Aricept, which eases symptoms of the disease but does not cure it, notched sales of ¥322.8 billion ($2.9 billion) before its patent expired.

The nod for Aduhelm sparked controversy from the outset. Some scientists have questioned whether the drug actually works in combating the cognitive decline that is a hallmark of Alzheimer’s disease — as well as its $56,000 annual price tag. In recent days, the FDA’s acting commissioner Janet Woodcock took the unusual step of saying she would request an independent federal review of the approval.

Asked last week, before news of the request for a federal probe, about whether the Aduhelm controversy may affect the FDA’s thinking on lecanemab, Cheung — who is also chairman of Eisai Inc., the company’s U.S. subsidiary — said he was "always hopeful the FDA acts in the interest of public health, and based on data and science.”

An Eisai spokesperson said Monday that the company does not see any impact on lecanemab from a potential federal probe of Aduhelm.

Eisai partnered with Biogen in 2014 to co-develop several Alzheimer’s related compounds. In 2017, Eisai exercised an option to expand the agreement to include Aduhelm. For lecanemab, Eisai will book all potential global sales while profit and costs are split with Biogen, Cheung said.

Researchers have long believed that interfering with the amyloid protein that builds up in Alzheimer’s patient’s brains was the key to treating cognitive decline from the disease, but the theory is unproven. Pharmaceutical companies have spent billions of dollars on experimental compounds targeting amyloid that have repeatedly failed to slow the disease’s progression.

Aduhelm’s accelerated approval was given on the basis of its ability to remove amyloid from the brain, but it was conditional on the fact that Biogen will still have to conduct another study to prove that the drug slows cognitive decline. In the meantime, the drug can be sold in the U.S.

Competitor Eli Lilly & Co., whose anti-amyloid compound donanemab also received a breakthrough therapy designation last month, said it aims to apply for an accelerated approval later this year.

The breakthrough designation for Eisai’s lecanemab was based on promising data from a Phase 2 trial in patients with mild cognitive impairment or mild Alzheimer’s. While the drug’s clinical data has looked promising so far, it’s difficult to make any judgment on the compound’s future without seeing the Phase 3 data, analysts said.

"For lecanemab, Eisai is betting that rather than just targeting the amyloid beta, that patients may also see clinical benefit around cognitive function,” said Tomohiro Tanaka, an analyst at SMBC Nikko Securities Inc. who covers Eisai. "That’s the best scenario for them. If it shows a clinical benefit, it wouldn’t be a conditional approval hinged on an additional clinical trial.”

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