Drug regulators in the United States have approved Xiidra, which is lifitegrast ophthalmic solution 5 percent, to treat dry eye disease. Xiidra is the first prescription eye drop approved to treat both the signs and symptoms of dry eye – a group of conditions where the tear fluid produced by the eyes is either insufficient to lubricate the eyes properly, or of the wrong consistency.
In their announcement on July 12th, the Food and Drug Administration (FDA) explain that Xiidra “is the first medication in a new class of drugs, called lymphocyte function-associated antigen 1 (LFA-1) antagonist.” The drug binds to a cell surface protein found on white blood cells.
Shire US Inc., of Lexington, MA, who make Xiidra, say the twice-daily eye drop solution will be launched during the third quarter of 2016.
If left untreated, severe forms of dry eye disease can cause pain and lead to ulcers or scars on the cornea, the clear tissue at the front of the eye.
“Normal tear production is needed for clear vision and eye health,” says Dr. Edward, director of the Office of Antimicrobial Products, FDA Center for Drug Evaluation and Research.
Dry eye can make it difficult to do every day things such as use computers, watch TV, or read for extended periods. It can also cause discomfort in dry environments such as inside airplanes in flight.
Estimates suggest around 16 million people in the U.S. are diagnosed with dry eye disease, which is more common in women than in men.
The safety and efficacy of Xiidra were assessed in four randomized, controlled studies involving over 1,000 dry eye patients aged 19-97 years, of whom 76 percent were female.
Trial participants received either Xiidra eye drops or placebo eye drops, which they applied twice a day for 12 weeks. Results show that compared with placebo, treatment with Xiidra showed more improvement in both the signs and the symptoms of dry eye.
A symptom is something that the patient senses or feels – for example itchiness – that is difficult or not possible to measure objectively. A sign is something someone other than the patient can observe – for example redness.
Reductions in signs and symptoms of eye dryness
In the trials, the participants were assessed at the start, and then at weeks 2, 6, and 12 for symptoms and signs of dry eye.
- Although it can occur at any age, elderly people frequently experience dry eye
- Nearly 5 million Americans aged 50 and older are thought to have dry eye
- Dry eye is more common after menopause.
The trial investigators used a patient-reported eye dryness score to assess symptoms. This showed a reduction in eye dryness at weeks 6 and 12 in all four studies, with improvements reported at week 2 in two of the studies.
To assess signs of dry eye, the investigators used an inferior corneal staining score. Three of the four studies showed a larger reduction in the Xiidra users compared with placebo at week 12.
The most common adverse reactions – reported in 5-25 percent of trial participants – were irritation, discomfort or blurred vision, and altered taste sensation (dysgeusia).
The FDA note that dry eye disease is much less common in children, and the safety and effectiveness of the new drug has not been studied in patients under the age of 17.
Shire note that lifitegrast is a “small-molecule integrin antagonist that binds to the integrin lymphocyte function-associated antigen-1 (LFA-1).” By binding to LFA-1, the drug blocks its interaction with a molecule called ICAM-1, a member of a family of molecules that are important in inflammation.
There have been suggestions that LFA-1/ICAM-1 interaction may contribute to a process that activates immune system T-cells and promotes their migration to target tissues. T-cells are thought to be involved in causing inflammation associated with dry eye disease.
However, while test tube experiments have given some further insights into this circumstantial evidence, the manufacturers note that the “exact mechanism of action of lifitegrast in dry eye disease is not known.”
“This approval will provide a new treatment option for patients with dry eye disease.”
Dr. Edward Cox