The Alzheimer's pipeline is as strong as ever. Now, we just need the patients

Calling all Alzheimer’s disease patients and caregivers: There’s a study out there waiting for you.

There are, at this moment, 187 clinical trials for the neurodegenerative disease underway, the highest ever on record, according to a new report from the Alzheimer’s Association (AA). The research was published in the association’s journal, Alzheimer’s & Dementia: Translational Research and Clinical Interventions, last week, featuring data scraped from the database. Last year, the report found 172 clinical trials in progress and 143 unique drugs. This year there are two fewer drugs on the list.

The boost in clinical development is thanks to a rise in interest among Big Pharmas, which have jumped back into the space after key successes from Biogen and Eisai with Leqembi and Eli Lilly’s donanemab. Industry-sponsored trials rose 8% over the past year to 108, accounting for 58% of all trials conducted, compared to 9% that were conducted through public-private partnerships and 32% by academic medical centers.

“The recently approved therapies provide treatment for a relatively limited segment (e.g., early AD) of the large and growing AD population,” the authors wrote. “They represent initial steps in the march toward more comprehensive treatments with multiple therapeutic options for those with or at risk for AD.”

Biologics, mainly monoclonal antibodies like Leqembi, are the therapeutic of choice, rising 10% over the past year in terms of trial uptake for disease-modifying therapies.

All this renewed interest is great for research. But AA found that recruitment has been a major challenge—especially for phase 2 and 3 studies. Recruitment can take as long as 100 weeks and, for some studies, up to 200 or more. This significantly slows down progress. Phase 1 trials are slightly faster, but not by much.

To fill all of the available clinical trials, 57,465 patients are needed, according to the report. That would mean 41,864 for phase 3 trials; 13,829 for phase 2 trials; and 1,772 for phase 1. For phase 4, which are studies that are conducted after approval—like for Leqembi and its predecessor Aduhelm, for example—4,632 patients are needed.

Biogen and Eisai have a requirement to conduct a post-approval study for Leqembi after receiving an accelerated nod for the therapy. The same caveat was added to Aduhelm's approval in 2021; however, the companies have mostly backed off that drug after its controversial launch

It’s not just the sheer numbers, either. A lack of diversity in trial recruitment has contributed to the delays and stalled desperately needed treatments from advancing in the clinic.

The approval of Leqembi, and phase 3 clinical success for donanemab, are great for patients. However, AA notes that the availability of treatments may further hamper clinical trial enrollment as patients opt for those instead of participating in research.