Clovis throws in the towel on solo Rubraca study in bladder cancer

Rubraca AstraZeneca
Clovis Oncology's PARP inhibitor Rubraca fell short in its monotherapy bladder cancer test, but it's on track for a first-in-class approval in prostate cancer. (Clovis)

Bladder cancer is tough to conquer, and Clovis Oncology just got a reminder of that. The company stopped a Rubraca trial in metastatic bladder cancer, saying too few patients had responded to the drug.

An analysis of preliminary data showed that response to Rubraca (rucaparib) as a solo treatment didn’t meet the trial’s threshold to continue, Clovis said in a Friday securities filing (PDF). The interim check by an independent monitoring committee “suggests that treatment with monotherapy rucaparib may not provide a meaningful clinical benefit to patients,” the filing states.

The Clovis drug, which is now approved to treat ovarian cancer, could have used a win in bladder cancer as it struggles to gain share in a hot-and-competitive drug class. Rubraca was the second PARP inhibitor on the market after AstraZeneca and Merck’s Lynparza but remains far behind sales-wise; it brought in just $95 million last year compared with Lynparza’s $647 million.

But the fact Clovis unveiled the trial halt in a Friday SEC filing rather than a Monday morning press release could make the news seem worse than it actually is, JPMorgan analyst Cory Kasimov said. His firm’s predictions for Rubraca revenue don’t count on any sales in bladder cancer, and the monotherapy trial didn’t turn up any unexpected side effects, he said.

RELATED: Clovis bolsters Rubraca's PARP-leading prostate cancer bid with big-time response data

“Though this is surely a disappointment ... we do note that this decision was not based on safety,” Kasimov wrote in a note to investors Friday evening. “Accordingly, we see this as having little read-through to additional indications that the company is pursuing.”

The trial, called Atlas, had enrolled 62 patients. Clovis says it will continue testing Rubraca alongside other drugs in bladder cancer, and it’s still planning to enroll patients with advanced bladder cancer that carries specific genetic mutations in a pan-tumor trial set to begin later this year.

Rubraca and its fellow PARP inhibitors are best known as ovarian cancer treatments, but two of the drugs are now approved for breast cancer—Lynparza and Pfizer’s Talzenna—and drugs across the class are under testing in a variety of other cancers as well.

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

Rubraca’s bladder cancer setback follows on the heels of some promising, if early, data for Rubraca in pancreatic cancer. In a phase 2 trial unveiled at the American Association for Cancer Research meeting last month, 37% of patients benefited from treatment, and the cancer’s progress stalled for a median 9.1 months after patients started on the drug. Rubraca is in trials for breast cancer, both as monotherapy and in combination with Bristol-Myers Squibb's Opdivo.

More immediately, the Clovis drug boasts a "breakthrough" designation in prostate cancer, and it's on track for an FDA filing there by the end of this year—and a first-in-class approval sometime next year. That indication could pad Rubraca sales by $580 million, Leerink analyst Andrew Berens said last year.

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