TLDR: Most medications are approved for a single purpose. For example, a drug is licensed to treat breast cancer. But what if that same drug could also help with multiple sclerosis, or another seemingly unrelated disease?
This approach is called drug repurposing, and it’s one of the most promising frontiers in medicine today.
One of its pioneers is Dr. David Fajgenbaum, a physician who turned his own battle with a rare disease into a groundbreaking medical discovery that is now helping thousands of patients worldwide.
Dr. David Fajgenbaum’s Story: From Patient to Pioneer
At just 25 years old, Dr. David Fajgenbaum nearly died four times in three years from Castleman Disease, a rare disorder that causes the immune system to attack vital organs. On his fourth relapse, he was administered last rites.
Chemotherapy offered a temporary reprieve, but Dr. Fajgenbaum knew it was not a sustainable solution. Rather than accept his fate, he began to search for an answer, using himself as the research subject. He scrutinized thousands of pages of his own medical records and collected and analyzed his blood samples for clues.
Dr. Fajgenbaum’s research pointed to an overactive immune pathway (mTOR). With his doctor’s support, he decided to repurpose an existing drug, Sirolimus, to treat himself. Sirolimus was originally developed and approved as an immunosuppressant for organ transplant patients.
Repurposing this drug saved his life.
In 2022, building on this breakthrough, Dr. Fajgenbaum founded Every Cure, a nonprofit dedicated to uncovering hidden uses for existing drugs. Researchers at Every Cure use an AI platform called MATRIX to compare thousands of drugs against thousands of diseases, generating millions of possible treatment matches.
Why Drug Repurposing Can Be a Lifeline for Difficult-to-Treat or Rare Conditions
The promise of drug repurposing lies in its efficiency. Existing drugs have already gone through rigorous testing for safety so they can often be redirected to new conditions at a faster rate, as well as at a fraction of the cost, of traditional drug development.
This approach is especially critical for rare diseases, where patient populations are too small to attract large pharmaceutical investment. For families navigating complex medical challenges, drug repurposing can open doors that would otherwise remain closed.
Success Stories: Drugs That Found New Purpose
Some of today’s best-known therapies were discovered through repurposing:
Sildenafil (Viagra) was first tested for blood pressure and angina. It’s now used for erectile dysfunction and pulmonary hypertension.
Thalidomide, once a failed—and tragically harmful—pregnancy drug, has been repurposed to treat multiple myeloma and certain complications of leprosy.
Metformin, long used for diabetes management, is now being studied for cancer prevention and healthy aging.
These aren’t outliers. They represent a pattern: existing drugs often have untapped potential that extends far beyond their original indication.
The Role of Artificial Intelligence in Modern Drug Repurposing
There are over 18,000 known diseases and 4,000 approved drugs. That creates more than 72 million possible drug–disease combinations.
No human researcher could systematically evaluate all those possibilities. But AI can.
AI tools like MATRIX can scan through massive datasets – including clinical trials, molecular pathways, patient outcomes, and genetic information – to prioritize the most promising matches. The AI flags drugs that are likely to help in diseases they weren’t originally designed for, often in a matter of weeks rather than years.
For patients with rare or treatment-resistant conditions, this technology represents genuine hope. It means that an answer might already exist—not in a laboratory years away, but in a medication sitting on a pharmacy shelf today.
RCM Health Consultancy: Accessing New Thinking for Complex Cases
MATRIX is making unprecedented advances in drug repurposing and giving new hope to people living with conditions that were once thought of as untreatable.
At RCM Health, we are proud to use the MATRIX AI tool when exploring novel treatment options for our clients who have complex medical challenges. For these individuals and families, innovation isn’t optional – it’s absolutely essential.
Just as Dr. Fajgenbaum’s discovery opened a path forward for Castleman disease; we apply the same spirit of innovation to find possibilities beyond the obvious.
Learn more about Dr. Fajgenbaum’s inspiring journey:
Ready to explore all available options for your complex medical case?
Contact RCM Health to schedule a consultation and learn how our comprehensive healthcare navigation services can help you access cutting-edge treatments, expert second opinions, and innovative approaches like AI-driven drug repurposing.