July 24 (Reuters) - Kodiak Sciences will abandon further development of its lead drug to treat a type of eye disease after it failed in two late-stage studies, the company said on Monday, sending its shares tumbling more than 50% in premarket trading.

Shares of the company, valued at $381.68 million as of Friday's close, were last down 55% at $3.26 before the bell.

The decision comes after the company failed to improve vision in two late-stage studies testing its drug, tarcocimab tedromer, against diabetic macular edema (DME) — the most common diabetes-related cause of vision loss.

The drug also led to higher, "unforeseen" incidence of cataracts over time in patients enrolled in the studies, Kodiak's Chief Executive Officer, Victor Perlroth, said in a statement. "We believe this likely was the primary driver for tarcocimab failing to achieve" the main goal in these studies.

The patients were randomized to receive either tarcocimab or Regeneron Pharmaceuticals' Eylea and evaluated for their visual acuity, or the eye's ability to distinguish shapes and the details of objects at a given distance.

Tarcocimab failed to show non-inferior visual acuity compared to Eylea, California-based Kodiak said.

The drug had earlier failed to match Eylea in improving the vision in a mid-to-late-stage trial in patients with wet age-related macular degeneration, a chronic eye disorder that causes blurred vision or blind spots.

Kodiak's pipeline also has another drug candidate, KSI-501, in early-stage trials to treat DME.

(Reporting by Mariam Sunny in Bengaluru; Editing by Shilpi Majumdar)