Novartis AG's (NYSE:NVS) vision-restoring drug Lucentis has been locked in a heated battle for market share with Regeneron Pharmaceuticals' (NASDAQ:REGN) Eylea ever since the latter won FDA approval in 2011.

Eylea is generating billions of dollars in sales every year, but a new drug that Novartis is developing could change that soon.

A big, growing market

Lucentis and Eylea are used to restore vision in patients suffering from wet age-related macular degeneration (wet AMD) and diabetic macular edema (DME).

Scientists work together in a lab.

IMAGE SOURCE: GETTY IMAGES.

AMD is a top cause of vision loss in people over age 50, and DME occurs in roughly 30% of longtime diabetes patients, or those who have had the disease over 20 years.

Both wet AMD and DME are the result of damage that's caused by fluid leaking into the macula from nearby blood vessels. Because damage to the macula reduces the ability to see things directly in front of patients, it significantly impacts day-to-day living by making it more difficult to recognize faces, drive, read, and write.

In the United States alone, there are about 1.5 million patients with wet AMD. Roughly 30% of long-term type 2 diabetes patients suffer from DME. Undeniably, these are already big indications; however, a longer-living and larger population, plus the increasing prevalence of diabetes, means that the number of people with these conditions is getting bigger every year. Currently, there are about 155,000 new cases of wet AMD and 300,000 new cases of DME are diagnosed per year in the United States.

Battling over billions

Lucentis won approval to treat wet AMD in 2006 and DME in 2012, and Eylea won approval for use in those two indications in 2011 and 2014, respectively.

Novartis is responsible for selling Lucentis internationally, while Roche Holdings (NASDAQOTH:RHHBY) sells it in the United States. In the first quarter, Novartis reported Lucentis sales of $445 million, and Roche reported Lucentis sales of 392 million Swiss francs ($402 million at current exchange rates).

Meanwhile, Regeneron Pharmaceuticals is responsible for marketing Eylea in the U.S., while Bayer (NASDAQOTH:BAYRY) commercializes Eylea internationally. Eylea's U.S. sales were $854 million in the first quarter, and overall, global Eylea sales were $1.34 billion, up 12% year over year.

But the billion-dollar market for wet AMD treatment is actually dominated by off-label use of another drug, Roche's Avastin. The drug has about 60% of the market share in the indication.

A new competitor coming?

Eylea has won away billions of dollars in sales from Lucentis and Avastin because it offers more patient-friendly dosing. Lucentis and Avastin are most effective when given monthly. Eylea can be dosed every eight weeks following an initial loading dose consisting of three monthly injections. 

Eylea's dosing advantage, however, could disappear given Novartis' latest trial results for a next-generation wet-AMD drug, RTH258 (brolucizumab).

Today, Novartis reported that use of RTH258 every 12 weeks met its primary endpoint of non-inferiority to Eylea in wet-AMD patients. In two head-to-head trials, 57% and 52% of patients were able to achieve similar efficacy to Eylea while remaining exclusively on RHT258's once-every-12-weeks treatment schedule. 

The data appear solid enough to win over regulators, so Novartis is ironing out the details necessary to file for FDA approval of RTH258. Management thinks it should be able to get an application for approval into regulators' hands next year, and once that happens, an FDA decision will come within 10 months. Assuming a filing early in 2018, RTH258 could conceivably be commercially available as soon as 2019. 

Ultimately, only time will tell if RTH258's dosing advantage unseats Eylea in the indication. Eylea has demonstrated significant real-world efficacy, particularly in tough-to-treat patients, so doctors may want to stick with it. Regardless, wet AMD and DME are huge indications, and there appears to be plenty of room for all of these drugs to be blockbusters.

Todd Campbell has no position in any stocks mentioned. His clients may have positions in the companies mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.