Roche ($RHHBY) says its closely watched PD-L1 checkpoint inhibitor atezolizumab (MPDL3280A) hit its primary endpoint in a midstage study for bladder cancer, shrinking tumors for a narrowly defined set of patients and setting the stage for early discussions with the FDA about the possibility of an accelerated approval for this "breakthrough" drug.
Roche's announcement of the Phase II success stops short of relating the actual data. Company officials note that the results are based on the study's second cohort of patients with locally advanced or metastatic urothelial bladder cancer, which includes "people whose disease progressed during or following previous treatment with a platinum-based chemotherapy regimen (second-line or later). People received a 1200-milligram intravenous dose of atezolizumab on day one of 21-day cycles until progressive disease (Cohort 1) or loss of clinical benefit (Cohort 2). The primary endpoint of the study was ORR (overall response rate). Secondary endpoints included duration of response, overall survival, progression-free survival and safety."
Results from the first cohort aren't available yet.
Significantly, Roche also notes that higher levels of PD-L1 (programmed death ligand-1) expression were associated with a greater response to the drug. Recent evidence in other programs linking the expression of PD-L1 with a drug response has bolstered Roche's chances of making a bigger, faster impact with its drug, which is designed to unleash an immune system assault against cancer cells.
In Roche's view, Genentech's PD-L1 target in the field--compared to the PD-1 approach by Merck ($MRK) and Bristol-Myers Squibb ($BMY) that's already been given early marketing approvals--gives the company a shot at near-term approvals for a drug that has the potential to clearly distinguish itself from the competition. Genentech--which won a "breakthrough therapy designation" from the FDA for this treatment--views PD-L1 as the more significant driver behind cancer. And while many of the early patient responses in the field look similar, Genentech believes it has an odds-on chance to prove that atezo can have a more durable effect on cancer with a lower likelihood of spurring toxicity.
A breakthrough designation gives Roche an inside track at the agency in seeking an early approval for atezolizumab. AstraZeneca ($AZN) has a PD-L1 approach of its own that it's moving as quickly as possible in the clinic.
|Roche CMO Dr. Sandra Horning|
Atezolizumab is in 11 Phase III studies amid a blizzard of 36 clinical trials. Its success is crucial for Roche, which is making analysts increasingly restive about its slow progress in bringing more drugs to the market.
"We are encouraged by the number of people who responded to atezolizumab and maintained their response during the study because minimal progress has been made in advanced bladder cancer for nearly 30 years," said Dr. Sandra Horning, chief medical officer and head of Global Product Development, in a statement. "We plan to present results at an upcoming medical meeting, and will discuss next steps with health authorities to bring a new treatment option to patients as soon as possible."