A breakthrough approach to treating Alzheimer's is facing major setbacks (MRK)

Many promising Alzheimer's drug trials have failed in the past few months.
The latest trial from drugmaker Merck stopped Tuesday after a committee found that the drug had "
These drugs are based on the "amyloid hypothesis," which some are still hopeful will be a successful way to treat Alzheimer's even with these setbacks.

It's been a hard few months for promising Alzheimer's clinical trials.

The results came less than a week after another Alzheimer's drug that was hoping to treat the symptoms of the disease failed two key clinical trials.

The amyloid hypothesis is taking a beating

So far, 2017 isn't looking much different from 2016, when there were four major flops for Alzheimer's drugs, including a highly-anticipated treatment from pharmaceutical giant Lilly.

That drug, solanezumab, as well as Merck's came out of research onamyloid hypothesis

"It's not what we wanted, it's not that leap forward for patients, but it's a step forward for the science,"

hat it's telling us is that there's a small effect on disease progression. But it's not zero. It's a clue that we're headed in the right direction."

Skovoronsky said that despite some setbacks, he remained more encouraged than ever by the amyloid hypothesis. Even so, Lilly has stopped its remaining phase 3 solanezumab trial, turning the focus onto the company's BACE inhibitor — the same kind of approach that the Merck drug took.

Lilly's not the only one that's holding on hope for the amyloid hypothesis. Bernstein analyst Ronny Gal noted that Merck's trial was expected to fail, in particular because it didn't screen for people with beta-amyloid plaques before getting started (diagnostics that screen for the plaques are still relatively new). That's not the case with the other trial Merck's continuing, where they're targeting people with even earlier stages of Alzheimer's. And treating as early as possible could be the key to proving out the amyloid hypothesis, Roger Pelmutter, Merck's head of research and development told Forbes.

There will be more opportunities to see that hypothesis in action, too. Biogen, another company that's big in neuroscience, expects to have data on its beta-amyloid targeting treatment in 2019.

Theres still more ahead in 2017, and not all rely on the amyloid hypothesis

While a lot seems to hinge on the amyloid hypothesis, drugmakers are working on other approaches that could be game-changing. Accera, the company looking into the metabolic aspects of Alzheimer's, will have data coming out on its phase three trial in the first quarter of 2017.

And Axovant, whose drug aims to treat the symptoms of Alzheimer's, will have phase three data coming out in the second half of 2017. Some of Axovant's competitors that have been going after the same target have had less-than stellar results.

On February 8, drugmaker Lundbeck announced its