MUNICH—Earlier this month, Clovis Oncology’s Rubraca picked up the FDA’s breakthrough designation in prostate cancer. And Friday, the company rolled out the data that helped it nab the agency’s distinction.
At the European Society for Medical Oncology (ESMO) annual meeting in Munich, the company highlighted results showing that its PARP contender provoked responses in 44% of patients with BRCA 1/2 alterations whose tumors could be evaluated using imaging studies.
It also significantly decreased the levels of prostate-specific antigen (PSA)—a protein whose levels are often elevated in men with prostate cancer—in 51% of evaluable patients with BRCA 1/2 alterations, Clovis said.
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Those numbers are “very encouraging,” Clovis CEO Patrick Mahaffy said in an interview, and should the drug go on to win an indication in the disease, the PSA data could particularly come in handy for marketing.
“Men with advanced prostate cancer are so aware of their PSA status and the physicians are so aware of the PSA status that absent a good PSA response rate, there’s some concern that the drug isn’t having the real active effect. And so in our case, to have an over 50% PSA response is really gratifying,” Mahaffy said, adding that the ability to speak to both response numbers “could be very important ultimately in commercializing the drug.”
The FDA breakthrough tag, which the FDA doled out Oct. 2, set Clovis up to become the first med in its class to reach the prostate cancer market—and to reap $580 million in sales in the process, Leerink Partners analyst Andrew Berens has predicted. He expects Rubraca to take a 40% slice of the pie by 2025, followed by Tesaro’s Zejula at 35% and AstraZeneca and Merck’s Lynparza at 15%.
“The benefits of being first are always pretty clear,” Mahaffy said.
That kind of share would be significant for Rubraca, which has been forced to play catch-up to its rivals in ovarian cancer. It originally hit the scene after Lynparza, and both Lynparza and Zejula beat it to an additional indication in ovarian cancer maintenance.
In order to win over doctors, though, Clovis will have to get its new prostate cancer data in front of them, a process it’s starting for the first time at ESMO. It’ll follow up next week at the Prostate Cancer Foundation’s annual symposium, and “it’s going to be important that we begin an effort with the patient advocacy groups to help” men with prostate cancer “understand the importance of knowing their BRCA status,” too, Mahaffy said.