What is cystic fibrosis?
Cystic fibrosis (CF) is a genetic disease affecting more than 70,000 patients worldwide. CF patients have viscous mucus accumulating in their vital organs. The mucus clogs tubes and organs thereby disrupting several processes in the body.

Pancreatic enzymes, necessary to digest food, are blocked from entering the intestines, so CF patients are not able to digest food by themselves. The thick layer of mucus in the lungs is a great environment for destructive bacteria. The thick mucus makes it hard to clear the lungs from these bacteria by coughing and results in regular infections and common inflammation. This process destroys the lungs and leads to frequent

What causes cystic fibrosis?
CF is caused by mutations (or defect) in a gene that is present in the DNA. This gene is responsible for expression of a protein called CFTR (CF transmembrane conductance regulator). As a result of the mutation, CFTR protein has no or limited function in CF patients. The lack of CFTR function results in reduced chloride transport that causes thick and sticky mucus in several vital organs in the body.

One in every 3600 babies is born with CF, mainly Caucasians in USA, EU and Australia. In several parts of the world CF is now part of newborn screening programs and patients get diagnosed early in life. There are many CF mutations known, the ΔF508 mutation is.

Treatment
For the majority of patients there is no therapy available that targets the basic defect of CF. CF patients are treated with a number of palliative medicines that target symptoms of the disease, varying form pancreatic enzymes and vitamins to mucus thinners and antibiotics. Patients spend a significant amount of their day taking their medicines, keeping them from leading a normal life.

For more information see the website of the Cystic Fibrosis Foundation.

ProQR is developing a novel drug for cystic fibrosis patients that suffer from the ΔF508 mutation, called QR-010. ΔF508 is the most common mutation in cystic fibrosis that affects more than 70% of all CF patients.

QR-010, is designed to work in a unique way. Unlike any other CF drug currently on the market it aims to repair the genetic defect in the RNA. The RNA is the “blueprint” for protein synthesis. By repairing this “blueprint” a normal healthy CFTR protein will be formed that is expected to have normal function. The goal of QR-010 is to repair the underlying defect in the RNA and with that stop the progression of cystic fibrosis.

Clinical trials

ProQR will soon start the first two clinical trials for QR-010 in CF patients. The first is a phase 1b clinical trial that will assess the safety and tolerability of QR-010 in 72 patients that are homozygous for the ΔF508 mutation. In this study we will also look at some measures of efficacy that are commonly used to see if a medicine is beneficial in cystic fibrosis patients.

The second study is a nasal potential difference, or NPD, study in 16 patients that are either homozygous or heterozygous for the ΔF508 mutation. This study is used as the first study in our proof of concept program for QR-010.

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