Dueling Glaxo, Astra Drugs Show Wider Benefits in Ovarian Cancer

(Bloomberg) -- Britain’s two largest drugmakers, betting on a new generation of cancer treatments that block tumor cells from fixing their damaged DNA, showed that these medicines work in a broad swath of patients.

Women with ovarian cancer treated with GlaxoSmithKline Plc’s drug Zejula had a 38% reduction in the risk of dying or seeing the disease progress, the company said on Saturday at a cancer conference in Barcelona. Glaxo said the study raises the possibility its therapy can work in other types of tumors. Research from AstraZeneca Plc and Merck & Co. showed their rival medicine, Lynparza, reduced the same risk by 41%.

The competing studies didn’t place one drugmaker clearly in the lead, instead bolstering the potential of a class of drugs know as PARP inhibitors, which doctors said may have been underappreciated until now.

“We have got confirmation that more women can benefit from PARP inhibitors,” Susana Banerjee, who heads research for the Royal Marsden hospital’s gynecology unit in London, said at a press conference before the studies were made public. “In the current setting, what we’re seeing is that they’re all equally effective.”

Glaxo bet big on PARP inhibitors last year, encroaching on Astra’s turf when it agreed to pay about $5.1 billion to buy Tesaro, which developed Zejula.

More Patients

The studies presented Saturday settled a key question: whether Zejula and Lynparza, both already proven to help ovarian cancer patients with a genetic mutation known as BRCA, would also work in women who don’t carry the mutation. That group makes up a majority of patients. Both drugs showed positive results, potentially unlocking a much larger market for their developers.

“PARP inhibitors have been underused and underappreciated,” Axel Hoos, Glaxo’s head of cancer research, said at the meeting. “This class of drugs can do a lot more.”

Glaxo estimates only 15% of almost 300,000 women globally diagnosed with ovarian cancer every year are eligible today to receive PARP inhibitors as their initial therapy. The drugs work by hindering a type of protein involved in DNA repair, increasing the likelihood that tumor cells will die rather than repair themselves and continue growing (PARP stands for poly ADP ribose polymerase, the family of proteins that enable the repairs).

Ovarian cancer, a disease that’s often diagnosed late because it triggers few symptoms, is likely to kill about 14,000 women in the U.S. this year.

Other Cancers

The data could transform how physicians view treatment options, said Hal Barron, Glaxo’s research chief. “There’s going to be little doubt that PARP inhibition and in particular, Zejula, will be potentially useful as a medicine” for a wider population, he said.

Touting rival Lynparza’s promise, Merck’s chief medical officer, Roy Baynes, said the fact that patients treated with the drug and Roche Holding AG’s Avastin lived 22.1 months without the disease progressing, compared to 16.6 months for Avastin alone, “has the potential to be practice-changing.”

What’s more, the results are encouraging for other cancer types as well -- something to be explored in future clinical trials, according to Barron.

Greater adoption of PARP inhibitors will depend on the number of patients being tested for mutations beyond BRCA and physicians’ willingness to change the way they use the drugs, analysts at Jefferies wrote in a report last month. Lynparza In one scenario could generate $3.1 billion in sales in ovarian cancer in 2025 while Zejula could yield $2.2 billion in revenue, the analysts predicted.

To contact the reporters on this story: James Paton in London at jpaton4@bloomberg.net;Tim Loh in Munich at tloh16@bloomberg.net

To contact the editors responsible for this story: Eric Pfanner at epfanner1@bloomberg.net, Rick Schine, Marthe Fourcade

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