The Power of Friendship: Advancing a Cure for CADASIL
Jeff Green and Steve Katelman
Jeff Green and Steve Katelman have known each other for nearly 20 years. Their friendship began when they discovered they had similar views on how to improve the digital advertising ecosystem. They grew even closer when they discovered they were both devilishly competitive.
“That started one time when we were at an industry event financed by one of my competitors, and there was somebody walking around with buckets of cheese,” Green recalled. “Then Steve asked me, ‘How many of those do you think you can eat?’ And I said, ‘More than you.’”
“And so it began,” added Katelman.
OK, but who won that initial cheese-eating competition?
“I think normally when it involves food, we call it a draw before somebody calls the police,” Katelman said.
“I think that was one of the first draws—a less exciting draw was when we had the competition to see who could fit the most gumballs in their mouth,” Green said. “We called a truce at like 84 when somebody was about to choke.”
So what happens when two close friends team up to channel that competitive drive into a shared mission for the greater good? The potential to impact one of society’s biggest problems—neurodegenerative disease.
Steve and Jeff, circa 2014
In 2021, Green signed on to the Giving Pledge, a promise by some of the world’s wealthiest people to give most of their fortunes to charitable causes. “My target is more than 90 percent of my wealth,” Green wrote in his pledge letter. “But I will also give of my time, my most precious commodity, to allocate those funds deliberately, and to be personally engaged.”
Little did he know at the time how personally engaged he would become with one of his generous grants.
Green is the co-founder and Chief Executive Officer of The Trade Desk, a successful digital advertising software company. To facilitate his philanthropic efforts, he started DataPhilanthropy, a charitable giving organization focused on causes where impact can be measured and scaled with data. He appointed Katelman, an advertising executive who had recently retired from 25+ years at Omnicom, as a key part of it.
“It was taking up a lot of his time, and he wanted me to help him because he trusted me and saw that so many of my previous skills could be utilized,” Katelman said. “So, we’re giving away hundreds of millions of dollars to causes we believe can advance through technology, just like we did with the advertising industry.”
Katelman is 60 years old. For close to 10 years, he’s known he has Cerebral Autosomal Dominant Arteriopathy Subcortical Infarcts and Leukoencephalopathy, or CADASIL. It is an inherited brain disorder caused by a genetic mutation that affects the muscle walls in the brain’s arteries, affecting blood flow to the brain. CADASIL is often characterized by migraine headaches and multiple strokes that in some cases can lead to dementia. Other symptoms include cognitive deterioration, seizures, vision problems, and psychiatric problems such as severe depression and changes in behavior and personality. The disease affects people variably and it has no known cure and few effective symptomatic treatments.
Katelman discovered he had CADASIL when a half-sister he had never known called him out of the blue to tell him she had it. After years of chasing a diagnosis for her symptoms, she wanted to let any blood relatives know of her findings. She was trying to find out whether anyone on either side of her parents’ family had been tested for CADASIL or experienced any strokes. Not long before that, Katelman felt disoriented and experienced a headache while attending a music festival. An eventual test confirmed the diagnosis.
Katelman’s CADASIL doctor is Fanny Elahi, MD, PhD, Associate Professor of Neurology, Neuroscience, and Pathology, Molecular and Cell-Based Medicine at the Icahn School of Medicine at Mount Sinai and one of the world’s foremost specialists in the study of brain blood vessel abnormalities and associated degeneration of the brain’s white matter. When Dr. Elahi told him about her work with data and the latest technology, and her vision for the future, Katelman made the obvious connection.
Steve Katelman and Dr. Fanny Elahi
“I said, ‘I think I know a guy that can help,’” Katelman said. “I said, ‘Jeff, you know I have this condition,’ and just without hesitation, he said, ‘Just tell me what you need me to do.’ And then he met Fanny and they clicked, and there we are.”
In December 2024, Green pledged a transformative grant of $8 million to fund Dr. Elahi’s research by establishing a translational center dedicated to studying cerebral small-vessel diseases—a key contributor to neurodegenerative disease. The goal is to address the major gaps in the drug development pipeline for CADASIL and to develop an effective treatment. Green, Katelman, and Dr. Elahi view the effort as more of a collaboration than a financial transaction. Treatments for CADASIL could have broader societal impact, given the many features it shares with other age-related disorders that affect the brain’s blood vessels.
“I think there’s an opportunity for perfect synergies—where DataPhilanthropy is very focused on data, and this challenge is very conducive to data and AI,” Green said. “Fanny’s extremely committed and passionate enough to navigate the system that often seems to prevent progress. And then Steve’s openness and collaboration and evangelism—there are some outcomes that could be world-changing on this.”
Katelman had seen several other CADASIL doctors around the country before he discovered Dr. Elahi a few years ago, when a friend read something about Dr. Elahi’s work at the University of California, San Francisco. After the Icahn School recruited Dr. Elahi to join its faculty in 2022, Katelman continued to see her.
Dr. Elahi has put together a multi-disciplinary team of researchers and collaborating institutions that aims to enhance the understanding of CADASIL by using cutting-edge technologies and modeling approaches. She described Green’s grant as “essential” to her work as a physician-scientist.
Dr. Elahi and team
“I’ve always said that if I couldn’t do research, I wouldn’t be a neurologist,” said Dr. Elahi. “It’s incredibly difficult to diagnose someone with a disease that has no available treatment. But as a physician-scientist, every patient I see not only deepens my understanding of the disease—it also strengthens my resolve to find solutions. I went into this field to solve problems. Knowing that our work could one day change the lives of patients fuels everything we do—and this grant makes that future feel within reach.” What’s crucial to Dr. Elahi’s research is the flexibility this grant will provide. Studying CADASIL with the goal of developing a treatment requires the ability to fail fast and pivot—a Silicon Valley-style approach to innovation that resonates deeply with a tech entrepreneur like Green.
“I’m a big believer in people that are passionate and focused—it’s the only way that you can put up with all the red tape, all the blockers,” Green said. “I just saw in her a commitment to progress the research. ‘One way or another we’ll figure it out’ is an attitude you often don’t hear from doctors.”
The potentially profound impact of this grant—and this unique collaboration with Dr. Elahi and Mount Sinai—is not lost on Green, either.
“There’s a version of the future, where Steve unfortunately having this can change thousands or more lives, just because we are more aggressive in getting ahead of it,” Green said. “It’s unbelievable to be a part of something that can potentially do that. To me, there’s all these challenges of trust in so much philanthropy. And then this case, when we’re all going as fast as we can and [we’re] open to transparency and data but also open to failure—I think we have the best chance at having the biggest outcome. I’m super optimistic and just eager to hear about progress.”
Fortunately for Katelman, he has thus far experienced few symptoms beyond occasional dizziness, lightheadedness, and fatigue, particularly after airline travel. He, too, is enthusiastic about the possibilities of collaborating with Dr. Elahi and Mount Sinai.
“Ultimately, obviously, if we found a cure to prevent it—awesome, you know?” Katelman said. “I’ve had a very successful and well-awarded advertising career, but this would be the feather in my cap.”
About the Mount Sinai Visiting Doctors Program
On May 12th, the Dubin Breast Center hosted its annual Fact vs. Fiction Luncheon and Symposium at the Metropolitan Club, providing a platform to discuss advancements in breast cancer care and women’s health. A distinguished panel of experts from Mount Sinai engaged an audience of more than 200 attendees, including Dubin Breast Center advisory board members, patients, families, and friends, with their insights into the latest innovations and emerging trends in breast health.
