GlaxoSmithKline's Benlysta has long enjoyed its place as the sole biologic approved to treat lupus, despite other drugmakers' forays into the field. But with competitors sniffing around, GSK is looking to bring Benlysta into another untried indication—and it could help the drug approach the blockbuster threshold. 

After two years, intravenous Benlysta plus standard-of-care induction therapies topped standard of care alone in improving kidney function in trial patients with lupus nephritis—an inflammation of the kidneys caused by the autoimmune disorder. That's a group the drug is not currently cleared to treat.

In a phase 3 study, dubbed Bliss-LN, 43% of lupus nephritis patients in the Benlysta arm achieved primary efficacy renal response—a measure of kidney function—compared with 32% of patients in the control arm. Patients on Benlysta also posted significantly higher response in secondary endpoints, including time to death or a kidney-related complication.

Thanks to a pledge it made to the FDA and the European Medicines Agency after Benlysta's initial approval in 2011, GSK was on the hook for the study, Sheri Mullen, GSK's senior VP of U.S. speciality pharma business, said. The data could make Benlysta the first drug approved to treat lupus nephritis, widening the product's patient pool, and GSK is working "fast and furious" to submit its findings to the FDA in the first half of 2020, she added.

"Our hope is that these data further reassure doctors today that Benlysta has a strong efficacy profile for these patients ...  I do hope it reinforces to the community that are very much committed to studying Benlysta across that spectrum," Mullen said.

Benlysta is the only biologic approved specifically for lupus and has moved slowly but surely toward blockbuster sales in the indication. In the first nine months of 2019, Benlysta posted $581 million in worldwide sales, a 32% jump from the same time period last year. 

Adding an indication could boost the drug's sales even further, with about 60% of 328,000 severe U.S. lupus patients suffering from lupus nephritis each year, GSK said. 

RELATED: GlaxoSmithKline lupus med Benlysta aims for growth injection with new subcutaneous approval

While the Bliss-LN study treated patients intravenously, GSK said its too early to speculate whether treatment with Benlysta's subcutaneous application would also be appropriate, Mullen said.

GSK secured a green light for that version back in July 2017, and the drugmaker touted it is a major time saver for patients who previously needed hourlong infusions. However, there are no studies currently underway for that version of Benlysta in lupus nephritis.  

GSK has also worked to boost its manufacturing of Benlysta, pumping $139 million into a Rockville, Maryland, plant in October to keep up with demand. 

RELATED: Roche touts phase 2 Gazyva data in lupus patients with a potentially fatal kidney complication

Being first to market in lupus nephritis could give GSK a leg up, particularly with challengers such as Roche coming after the indication. In June, the Swiss pharma giant posted phase 2 data showing blood cancer med Gazyva on top of standard-of-care therapy bested standard of care alone in achieving complete renal response for lupus nephritis patients. 

Gazvya would be a major competitor, as it sports FDA approvals in chronic lymphocytic leukemia and follicular lymphoma and hit $393 million in sales in 2018, a 40% jump on the year.

A third competitor in the field, Aurinia's late-stage lupus nephritis candidate voclosporin hit its primary endpoint earlier this month in a phase 3 trial. Aurinia said it also aimed to file its data with the FDA in the first half of 2020.

Editor's Note: This story has been updated to correct an error. Sheri Mullen is GSK's senior VP of U.S. specialty pharma business. The story has also been updated to clarify Benylsta's subcutaneous application for lupus nephritis and added information on Aurinia's late-stage candidate voclosporin.