Clovis' Rubraca pulls ahead of rivals in prostate cancer with 'breakthrough' nod

Rubraca, first approved in ovarian cancer, is in testing for other new uses, in breast cancer and in combination with Bristol-Myers Squibb's Opdivo. (Clovis)

Clovis Oncology may have seen a setback last month with a Securities and Exchange Commission settlement, but its cancer drug Rubraca is going full steam ahead. Rubraca nabbed a breakthrough designation for a new use in prostate cancer, putting it in line for a sped-up approval—and the first nod in its class for the disease.

A prostate cancer indication would take Rubraca beyond ovarian cancer, where it debuted behind Merck & Co. and AstraZeneca's still-dominant Lynparza, which continues to rack up first-in-class indications; it won a first-line approval this summer. And Rubraca nabbed its maintenance nod not only after Lynparza, but after Tesaro's Zejula as well.

Rubraca could own the prostate cancer market, at least at first, Leerink analyst Andrew Berens noted for investors Wednesday morning—a position that pad its sales by $580 million. The company has said it plans a submission for the new use in the second half of 2019.

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RELATED: Clovis' Rubraca joins the 'three-horse' PARP race in recurrent ovarian cancer

That timing "could lead to preferential use as clinicians gain familiarity with PARP use in this population," the analyst noted, adding that his firm expects Rubraca to grab about 40% share in PARP-appropriate cancer patients, ahead of Zejula's 35% and Lynparza's 15%, by 2025.

No wonder Clovis shares gained 10% by day's end Tuesday and have risen another 7.72% in early Wednesday trading. That's a turnaround from investor sentiment after second-quarter earnings, when worries about the prostate cancer data sent shares tumbling at an even greater rate.

The breakthrough nod (PDF) relies on a phase 2 trial—in patients with BRCA-mutated metastatic cancer that's progressed despite chemo and treatment with an older type of drug that includes Pfizer's Xtandi and Johnson & Johnson's Zytiga—on tap for presentation at the European Society of Medical Oncology meeting in mid-October, and given the breakthrough news announced Tuesday, it's likely to be impressive data, Berens said.

And the FDA's move suggests the data "are strong from a regulatory perspective," he wrote, pointing out that the agency's criteria for a breakthrough designation requires evidence that shows a drug may substantially beat available therapies on at least one clinically significant endpoint.

RELATED: AstraZeneca pioneer Lynparza scores with Zytiga combo in prostate cancer

Clovis may not have the prostate field all to itself for long, however; Merck and AZ are plotting a breakthrough therapy request next year. Pfizer's also testing its PARP candidate talazoparib in prosate cancer, in untreated patients and those who've failed after one round of therapy.

Meanwhile, Clovis and its competitors are working to push into other cancers. Rubraca, for instance, is under study alongside Bristol-Myers Squibb's immunotherapy Opdivo in triple-negative breast cancer as well as ovarian cancer. And Pfizer in June won priority review for talazoparib in breast cancer.