Desmoid Fibromatosis (DeFi) Trial

We measure ourselves by the impact we have on people with rare tumors.
Let’s go big.

We are conducting a Phase 3 clinical trial to evaluate the safety, efficacy, and tolerability of nirogacestat in people over the age of 18 with progressing desmoid tumors.

Learn about joining
a clinical trial

Clinical trials are essential research practices for advancing science, enhancing medical knowledge, and improving patient care. They are carefully designed to maximize safety for patients and are closely monitored at every step, but there are risks as we explore new science.

Scientists make the discoveries, but clinical trials can’t happen without patients. If you are considering joining a trial, we thank you. And we want to make sure you completely understand your role, your rights and what is expected of you.

Before volunteering for a clinical trial, you should talk to your doctor and read about the clinical trial process to ensure you understand the risks – and your rights. You will be asked to sign an Informed Consent form before joining the trial. Learn more by exploring our brochure, Understanding Clinical Trials.

What is the DeFi trial?

The DeFi (Desmoid/Fibromatosis) trial is a Phase 3 clinical trial designed to evaluate the safety, efficacy and tolerability of an investigational drug called nirogacestat in people over the age of 18 with progressing desmoid tumors. Nirogacestat is an oral, small molecule inhibitor of gamma secretase – in other words, a pill that is designed to inhibit a protein in the body that is known to contribute to desmoid tumor growth.

The DeFi trial is fully enrolled and is no longer accepting new patients. For medical professionals seeking additional information about the DeFi trial, please email