By Julie Steenhuysen

CHICAGO (Reuters) – Japanese drugmaker Eisai Co (OTC:) on Monday began its application process for its experimental drug for early Alzheimer’s disease using an accelerated approval pathway, the same path that helped Eisai’s development partner Biogen Inc (NASDAQ:) win U.S. approval of its medication in June.

Aduhelm by Biogen/Eisai was the first Alzheimer’s treatment to receive approval. But, the FDA’s controversial application of the accelerated approbation process (which authorizes medications for very severe conditions with no strong proof that they are beneficial to patients) has drawn heavy criticism.

Aduhelm was approved by Biogen and Eisai based on the evidence it could reduce brain plaques (a known contributor to Alzheimer’s), rather than convincing proof it will slow down progression. To prove that the drug is effective, companies must conduct confirmatory research.

Eisai is currently leading development of the Alzheimer’s drug Lecanemab. It has used evidence from its midstage trial to show that it removes brain plaques in a greater extent than Aduhelm and causes less brain swelling.

As it goes through regulatory processes, Eisai will learn from the experiences of its partner. Ivan Cheung (president of Eisai’s global neurology division) stated in an interview that the company wants to be as transparent and open as possible.

Eisai’s application will be submitted to FDA on an ongoing basis. The goal is for the FDA application to be completed within the next few weeks. Data from the midstage study of 856 patients will be submitted by Eisai. It showed that after 18 months, 80% of patients no longer had amyloid in their brains.

Cheung stated that this benefit was also associated with some patient improvements. In April, the trial was published by Alzheimer’s Research and Therapy. This peer-reviewed journal is a peer review journal.

The FDA stated that the confirmation trial could be delayed for several years, as a key issue in the Aduhelm approval. Eisai is already fully enrolled in Phase III of a confirmatory trial. Cheung anticipates that results will be available before 2022.

Cheung explained that the FDA understands the importance of validating clinical evidence.

Aduhelm was initially given a wide indication by the FDA that extended beyond those studied during its clinical trials. Cheung claimed that the company does not want the FDA to take into account the specific study population of the drug, which is early Alzheimer’s.

Eli Lilly and Co. (NYSE:) said that in July, it plans to request accelerated approval for donanemab, its Alzheimer’s treatment candidate. This is based on data from mid-stage. Lilly stated that it will seek U.S. regulatory approval before year-end.