Clovis shares dented after lung cancer contender mirrors AstraZeneca's rival

Shares of Clovis Oncology slid 10% ($CLVS) on Wednesday as investors and analysts juggled a new data set on its closely watched lung cancer drug rociletinib (CO-1686). Even though the updated Phase II results were promising, the numbers slipped a bit from its last snapshot delivered last summer at ASCO. And slipping now looks a lot like falling behind in its race with AstraZeneca's ($AZN) rival AZD9291, frequently touted as one of the pharma giant's top R&D comeback programs.

Examining the results on 56 patients with a T790 mutation, the key figures were a 67% overall response rate (ORR) among patients with 10.4 months of progression-free survival (PFS). The problem was that analysts that track Clovis wanted to see the same 12-month PFS rate reported last summer. That 10.4-month figure is looking uncomfortably close to AZD9291's last reported 9.6 month PFS rate, even though the ORR was back up over last summer.

Boulder, CO-based Clovis is still very much a contender in this race, but the programs are increasingly looking like twins with a lot of market rivalry to look forward to. Durability of response could be a key distinguishing factor for this drug, if there is an edge in its favor.

Howard Liang, an analyst at Leerink, agreed that the numbers are uncomfortably close, but teased out a reason to be upbeat about Clovis's chances.

"Importantly in T790M- patients," he noted, "there was a 36% ORR (4/11) with a 7.5 month PFS, which appears to compare favorably to the 21% ORR (13/61) and especially a 2.8 month median PFS seen with AZD9291 at ESMO in these patients. While these data are early ... we believe there is a suggestion of potential differentiation for rociletinib in efficacy resulting from IGF1R inhibition."

Perhaps the message was taking hold today, as Clovis' shares rebounded 4% in midmorning trading.

Clovis CEO Patrick Mahaffy

Clovis CEO Patrick Mahaffy, who likes to joke a bit about the showdown when you go one on one, is staying focused on a regulatory application next year--a major turning point for the biotech.  

"These data demonstrate the very encouraging activity and tolerability observed with rociletinib at our go-forward dose of 625mg BID, and our step-down dose of 500mg BID," said Mahaffy in a statement. "We are now expanding beyond our initial focus on T790M-positive patients and are very enthusiastic about our expansion into front-line patients with TIGER-1, and soon, into an all-comer population of patients with acquired TKI resistance, including both T790M-positive and T790M-negative patients with TIGER-3. We are actively preparing for the first of our planned regulatory filings, which include the U.S. NDA and E.U. MAA in mid-2015."

- here's the release