NPR: A Couple's Quest To Stop A Rare Disease Before It Takes One Of Them

A Couple's Quest To Stop A Rare Disease Before It Takes One Of Them, 19 June 2017

(This is about fatal familial insomnia, a prion disease.)

"In less than a year, Sonia's mom died.

An autopsy showed Kamni had died from something rare -- a prion disease. Specifically, one called fatal familial insomnia because in some patients it steals the ability to fall asleep.

Basically, certain molecules had started clumping together in Kamni's brain, killing her brain cells. It was all because of one tiny error in her DNA — an "A" where there was supposed to be a "G," a single typo in a manuscript of 6 billion letters.

Sonia sent a sample of her own blood to a lab, where a test confirmed she inherited the same mutation."

"Today, Sonia and her husband live and work in Cambridge, Mass., where they are both doctoral students in the lab of Stuart Schreiber, a Harvard professor of chemistry and chemical biology. Over the past several years, the couple has completely redirected their careers and their lives toward this single goal: to prevent prion disease from ever making Sonia sick."

"Sonia is 33 years old. On average, people with the kind of genetic mutation she has usually start to show symptoms at age 50. But they could surface at any time. Symptoms of fatal familial insomnia have set in as early as age 12 and as late as 84. Once they do, it's a rapid decline — like Alzheimer's disease on fast-forward."

"They need to keep Sonia from getting sick in the first place. And they need to do it quickly. But right now, Sonia appears to be just fine, and that's actually one of the first obstacles.

Across medicine, there is an understandable resistance to testing experimental drugs on healthy people. That's why, traditionally, drug trials go something like this: Take a group of people who are sick, give some of them an experimental medicine, and wait to see if it makes them get better, live longer, or decline more slowly than people who didn't get the drug.

But Sonia has to convince the medical establishment that, especially in the age of genetics, some people who seem perfectly healthy should be considered patients."

"Other efforts at treating prion disease have focused on preventing the misfolded proteins from killing brain cells, or on preventing them from accumulating. Sonia and Eric have a different approach.

'We're really interested in preventing the misfolding in the first place,' says Sonia.

'Sonia's brain is producing this mutant protein,' Eric says. 'But as far as we know it's not misfolded yet, and the disease process hasn't started. I want her brain to be producing half or less of the amount of that protein as she is [producing] right now, because we know that less is better.'

Essentially, they want to muffle the faulty gene in order to reduce the amount of prion protein floating around in Sonia's brain.

But a key question right now is this: Say they make the right drug and give it to Sonia and others with her type of mutation. If the goal is to change nothing about her current health, then how will they know it's actually working?

A traditional clinical trial is out of the question, Eric says.

It would be unethical and untenable he says, to 'just treat half of the people with a drug and half with placebo and then wait 30 years to see when they die.'

'Instead, we need a biomarker,' Eric says. 'We need some laboratory test that we can run on a living human to see if the drug is having its effect.'

The answer, Sonia and Eric hope, could be in a very cold refrigerator in the lab where they work. It's full of samples of spinal fluid. In mouse studies, at least, reducing prion protein in the brain seems to delay disease progression.

So, Sonia and Eric are now studying samples of spinal fluid from all sorts of people — from people who already have symptoms of prion disease, from others like Sonia (who have mutations for prion disease but no symptoms yet) and from healthy controls. The aim is to establish how the levels of protein in the samples change over time, to figure out if protein levels would be a good enough measure to say, 'Yes, this drug works.'"