Biogen’s filing of aducanumab, an investigational Alzheimer’s drug, for U.S. approval is drifting from its initial goal.

The company had planned to seek the license early this year, but it recently said it would start discussing the FDA filing in the third quarter. The delay prompted some skeptics to doubt aducanumab’s efficacy.

In a regular meeting with shareholders on June 3, Biogen said it would seek the nod, not only in the U.S. but Europe and Japan simultaneously, in the third quarter.

Aducanumab was the most closely watched topic in the June meeting because winning the regulatory nod would make the medicine the world’s first Alzheimer’s disease treatment.

In March last year, Biogen announced that it would suspend its phase-3 trial son aducanumab because a futility analysis concluded that the trials would not reach their primary endpoint. However, the company reversed its stance in October and said the experimental drug showed meaningful clinical improvement in treating Alzheimer’s.

Biogen said aducanumab achieved both the primary and secondary endpoints in the phase-3 EMERGE trials and showed partial clinical improvement in some high-dose groups in another phase-3 ENGAGE trial.

At the time, the company said it would start a discussion with the FDA and submit a license application for aducanumab in the U.S. in early 2020.

However, the company has yet to do so.

At the latest meeting, shareholders asked the company when it planned to seek approval. They also asked if the drug gets approved, when patients would be able to use aducanumab and which dose would be the most effective given the clinical results.

Biogen said, “We will resume discussion for the submission of the aducanumab license application in the third quarter.”

The company was working with the FDA over the data submission, but the process did not go smoothly due to the spread of Covid-19, it added.

Company did not comment on any expected marketing schedule or for which dose it would apply.

Biogen brushed off skepticism over the effect of aducanumab, emphasizing that the drug proved the efficacy against Alzheimer’s in phase-3 trials and that it was Biogen’s most promising drug.

In a previous meeting with investors, Biogen announced that it completed the building of a production facility for aducanumab in Switzerland.

Still, some experts kept raising questions over the investigational Alzheimer’s drug. J.P. Morgan analyst Cory Kasimov cited a survey on 30 physicians and said that most of the respondents were negative about aducanumab approval.

However, if it gets the FDA nod, many doctors will prescribe the drug, the survey showed.

The survey on 20 university hospital physicians and 10 community doctors showed that 94 percent of them thought aducanumab was at least “somewhat tolerable” for patients.

However, they were split on whether the phase-3 data that will support Biogen’s FDA application is “clinically meaningful.”