Xiidra is only the second dry eye disease prescription drug to be approved in the United States. Remarkably, FDA’s approval of Shire’s Xiidra (lifitegrast ophthalmic solution) comes more than a decade after the agency granted approval to the first-ever prescription treatment specific to dry eye disease, Allergan’s Restasis (cyclosporine ophthalmic emulsion). Restasis is indicated to promote tear production in cases where it is reduced due to inflammation associated with dry eye disease. DRG research suggests that Restasis is prescribed on label and, generally, whenever inflammatory ocular processes are suspected in dry eye disease. Anti-inflammatory corticosteroids formulated for ophthalmic delivery are used short-term only, to provide relief before the onset of action of Restasis, and because extended administration can cause steroid-induced side effects. The label for Xiidra appears broader than that for Restasis—the new drug is indicated for the treatment of signs and symptoms of dry eye disease without specifying disease subtype or an underlying inflammatory disease process. However, because Xiidra is believed to suppress T-cell mediated inflammation, and based on insights from DRG’s primary research, ophthalmologists appear likely to consider prescribing Xiidra largely to the same patients whose clinical findings would suggest a benefit from Restasis, i.e., where inflammation is involved in dry eye disease.
The dry eye disease market overall could expand with launch and uptake of Xiidra in the United States. Assuming Xiidra targets the same patient population as is currently treated or eligible for treatment with Restasis, will the newer agent threaten or even displace long-reigning Restasis in the United States? Some degree of switching from Restasis to Xiidra is likely to occur, though the possibility of an eventual first-line use of Xiidra over Restasis will depend on many factors, including Xiidra’s clinical profile as it emerges in day-to-day practice, the level of reimbursement by insurance providers, and the overall cost of the drug. Beyond switching from Restasis to Xiidra, some dry eye disease patients who are not currently on Restasis—for example, those who discontinued Restasis due to lack of efficacy or side effects, such as a burning sensation that is relatively common upon administration—could be initiated on Xiidra. DRG primary research further suggests ophthalmologists would consider combining Restasis and Xiidra, although questions remain as to the acceptance of such an approach, given the lack of clinical data to support combination use. Overall, therefore, a higher number of treated patients and combination treatment could grow the dry eye disease market in the United States, even though some of Xiidra’s uptake will likely be at the expense of Restasis.
Xiidra will fulfill some of the current unmet need in dry eye disease. Dry eye disease is heterogeneous in presentation and in underlying disease processes, yet the number of available treatment options for dry eye disease is limited. Like Restasis, Xiidra targets inflammation, but because it acts on a different inflammatory pathway, could have quicker onset of action, and will likely display a distinct side effects profile, Shire’s new therapy represents a differentiated treatment alternative. However, even after Xiidra becomes available, opportunity will remain for new treatments acting through alternative pathways, leaving room for emerging agents such as Allergan/Mimetogen’s tavilermide (MIM-D3), a nerve growth factor mimic. And while the percentage of dry eye disease patients who could benefit from novel treatments may be small, e.g., patients with severe disease who do not respond to current anti-inflammatory agents, the large size of the overall patient population, estimated at tens of millions in the United States alone, translates into a substantial commercial opportunity—Allergan reported global 2015 full year sales for Restasis in excess of $1 billion, most of which was attributable to the United States.
The availability of Xiidra will also benefit Sjögren’s syndrome patients. Sjögren’s syndrome is an autoimmune disease characterized by dry eyes and dry mouth, resulting from the immune system mistakenly attacking the lacrimal and salivary glands responsible for tear and saliva secretion, respectively. Though not a rare disease, no therapy is currently approved specifically for Sjögren’s syndrome, and treatment therefore is symptomatic and/or aimed at treating a primary autoimmune disease, which Sjögren’s syndrome may accompany. Treatments for dry eye disease are routinely recommended and prescribed in Sjögren’s syndrome to relieve dry eye symptoms. Because Sjögren’s syndrome is believed to be driven primarily by inflammatory processes, Xiidra could prove particularly well suited for treatment of dry eye in Sjögren’s syndrome patients. Xiidra’s uptake in Sjogren’s syndrome is unlikely to be the principal driver of future sales of the drug; still, the fraction of prescription dry eye treatments that goes to Sjögren’s syndrome is not inconsequential. Above all, a new dry eye treatment option that could prove uniquely beneficial in Sjögren’s syndrome would fulfill an unmet need in a disease where dry eye manifestations are considered to be more severe than in the dry eye population as a whole.
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