Pericarditis, Autoimmune Disorders & the Science & Business of Biologics

What I’ve learned so far from idiopathic recurrent pericarditis—and what it says about the future of diagnosis

A couple weeks ago, I hosted a dinner for startup founders in Denver. Fourteen people around the table. I didn’t talk to all of them, but the two founders sitting next to me had both gone through major autoimmune breakdowns while building their companies. One had a heart attack. The other lost all his strength and thought he might never build again. Both in their 30s. Both previously healthy.

Their stories hit close to home.

Yesterday, I flew to Cleveland, OH for my fourth appointment with the Cleveland Clinic in the last three years. I’ve been seeing Dr. Allan Klein—one of the world’s top experts on pericarditis.

The early years: uncertainty and misdirection

In 2018, I started noticing irregular episodes of chest pain. It began as a dull ache on deep breaths, then progressed into headaches and waves of fatigue. I assumed it was a weird symptom tied to a cold or seasonal virus. But by 2019, the flares were happening more often—six times that year.

In 2020, the intervals shortened again. Random attacks, no warning. I began calling them “flares.” I was researching heavily and saw a rheumatologist who thought it might be costochondritis. I was prescribed colchicine. And prednisone, if it got severe. I also saw a pulmonologist, wondering about pleurisy. But the challenge with autoimmune flares is: they pass before the doctor can get you in to examine them. Every appointment was in a “non-flare” state. So I was evaluated as if nothing was wrong.

Mid-2020, a major flare put me in bed for a week. I finally tried prednisone—and it was like flipping a switch. Within hours I was back to normal. The next day I rode 25 miles as fast as I could through Atlanta, amazed at how strong I felt. A close friend, a surgery resident at Emory, later scolded me: “You’re a fool to exercise on prednisone.”

No diagnosis, no clarity

The remainder of that year, I took a lot of prednisone. I also started seeing a new rheumatologist who tried a second colchicine-based regimen. But still—no diagnosis. No one mentioned pericarditis. It felt like guesswork.

Then, in June 2021, I thought I was having a heart attack and went to the ER before a work trip. The echocardiogram showed a large pericardial effusion—fluid around the heart. For the first time, someone said: this looks like pericarditis.

That’s when I found Dr. Klein online, who was involved in testing a new biologic drug called Rilonacept through a company called Kiniksa. Early results looked promising. I stayed on prednisone while my rheumatologist tried to secure prior authorization for a different biologic—Anakinra. It was denied. No one knew what the underlying cause was, so insurance wouldn’t pay.

By October 2021, I was determined to see Dr. Klein and was able to get an appointment scheduled with the help of my Emory doctors for February 2022. Cleveland was covered in snow, and the city felt alive with history & science—steel, medicine, Case Western. I spent a full day getting tested. When I finally met with Klein, he said I had idiopathic recurrent pericarditis. No known cause. He recommended Rilonacept, recently FDA-approved. It would require weekly injections. A better option than Anakinra, which requires daily injections. The alternative? Surgical removal of the pericardium.

He also told me to stop exercising for at least 12 months.

The drug that worked

I flew home and waited for prior authorization. During that wait, I went into one of the worst flares I’ve ever had. Klein asked me not to take prednisone—it would interfere with the biologic’s introduction. So I waited, barely able to get out of bed. It was a low point, and I remember feeling that if the drug didn’t work, this disease would eventually ground me down and kill the energy I needed to be a good founder, father, and husband.

A few days in, the drug arrived. A nurse came to teach me how to inject it. Mary Howard injected the first dose. I went to sleep.

When I woke up, I was pain-free.

I’ve been on Rilonacept ever since, and I’ve been flare-free for three years.

What biologics mean for chronic conditions

Rilonacept is a biologic—a class of drugs that suppress the immune system and have revolutionized treatment for diseases like rheumatoid arthritis, lupus, Crohn’s, and pericarditis. Because they suppress immunity, doctors were hesitant to prescribe them during COVID. But in cases like mine, they are life-altering.

For the first 18 months, I stopped exercising entirely. I came to terms with the idea that I might never be a runner, cyclist, or soccer player again. But about a year in, Klein gave me the green light to start slowly. I began rebuilding in Atlanta with a couple of good friends—running, riding, gradually getting back to form.

Yesterday’s MRI showed minimal and receding inflammation. And that improvement has held despite a significant increase in anaerobic training. The big question now is: Do I stay on this drug forever? Or is there a path off? Klein suggested I might be a good early candidate for a new drug that could help patients wean off Rilonacept. A number of pharma companies are working on this problem—both because incidence of pericarditis appears to be rising, and because there’s no clear taper protocol once you’re stabilized.

What I wish I’d known earlier

If you’re dealing with recurring, unexplained symptoms—especially chest pain, fatigue, or inflammatory markers—document everything. Keep a flare journal with dates, symptoms, medications, and any lab work. Try to get imaging or bloodwork during a flare. Don’t assume your first diagnosis is correct. And don’t assume your doctor will connect the dots—especially if they’ve never seen your condition before. Online patient communities (Reddit, Facebook, rare disease forums) can often surface diagnostic patterns and treatment insights well before you’ll hear them in a clinic. And because the LLMs have trained so heavily on Reddit forums, they, too, are excellent tools for diagnostic exploration. When I was researching in 2018, 2019, 2020, pre-chatGPT, my searches kept leading me to the wrong answers.

The science and business of biologics

Biologics—unlike most medications, which are synthesized chemically—are grown using living cells. They're designed to interrupt the body’s immune response when it goes haywire, like in my case, where the immune system decides (for reasons still unknown) to attack the lining around my heart.

While the concept dates back to the late 19th century (vaccine serums, antitoxins), the modern biologics era kicked into gear in the 1980s with the first recombinant drugs. The crown jewel was human insulin, approved in 1982—it was bioengineered and dramatically safer than animal-derived versions. Then came monoclonal antibodies in the ’90s, like etanercept and Humira, which reshaped the treatment of autoimmune diseases such as rheumatoid arthritis and IBD. From there, the field exploded.

Rilonacept was originally developed by Regeneron. It was later licensed to a company called Kiniksa, which saw a clear opportunity to bring it to market for pericarditis specifically. The FDA approved it in 2021, and since then, it’s become the go-to treatment for people like me. It’s not cheap—about $20,000 per month—but the impact is profound, and insurance typically covers it once a diagnosis is confirmed.

In terms of business performance, the drug (marketed as ARCALYST®) generated $417 million in revenue last year and is on track to cross $600 million in 2025. Even more notable: the company is now profitable. And they’re already investing in next-gen versions—new biologics that could require monthly or even quarterly injections instead of weekly ones.

I find the business and science history fascinating. You have deep science, long timelines, massive capital investment, and then—when it works—a life-changing product with both clinical and financial leverage. The bet on Rilonacept was a big one. And it’s working.

The system isn’t designed for cases like this, but AI can change that

This week, I came across a Reddit post from a young woman who described almost my exact journey. Years of flares, repeated misdiagnoses, ER visits, prednisone prescriptions, doctors telling her it was “costochondritis.” She was treated like a hypochondriac. Finally, someone ran the right test and diagnosed her with pericarditis.

There are thousands of these stories on a pericarditis subreddit alone.

Most doctors see patients for 10 minutes. Most patients don’t flare during that window. Most people don’t even know pericarditis is a thing. So when symptoms present, they’re hard to diagnose.

This is why I believe in the potential for AI to become a powerful second opinion that massively augments both patient advocacy and the quality of conversations between patients and doctors —especially for invisible or rare conditions. Imagine an LLM trained on Reddit threads, peer-reviewed journals, and anonymized patient data, able to identify patterns across thousands of patients with symptoms like “chest pain + normal EKG + elevated CRP + 2-year cycle.” It could flag possibilities long before a single specialist gets involved.

From there it gets even more exciting when we move into joining and productizing real-time health data from wearables with diagnostic imaging and clinical record data. AI can make sense of those enormous data sets and move us toward predictive and preventative care.

Thank you, Dr. Klein. And thank you to everyone building biologics.