Safety Issue Triggers Partial FDA Hold for Aduro Bio

Xconomy San Francisco — 

Aduro Biotech ran into some trouble earlier this year when one of its cancer immunotherapies failed a clinical trial. Now the Berkeley, CA, company has a safety problem and a clinical trial delay to deal with.

Aduro (NASDAQ: ADRO) said this morning that one of the patients in its ongoing clinical trials of CRS-207, a drug based on the bacterium Listeria, tested positive for Listeria. Though that patient subsequently got antibiotics, was rid of the infection, and is reportedly doing well, the FDA has since placed a “partial” clinical hold on trials using any of Aduro’s Listeria-based investigational treatments. That means while trial patients currently undergoing treatment can stay on Aduro’s Listeria-based drugs, Aduro can’t enroll any new patients in trials without resolving the issue.

Aduro said it is working with the FDA to lift the hold and planning to change some study criteria. It plans to administer antibiotics to patients after treatment, for instance, and exclude patients who are on immune-suppressing therapies. It said it will bring its revised study plans to the agency later this week.

Aduro is working on three different types of cancer immunotherapy. It said the hold only affects its Listeria-based work—which includes CRS-207 and three other experimental drugs in early-stage testing—not its two other approaches. With CRS-207, Aduro aims to render Listeria non-infectious and engineers it to mimic certain traits of cancer cells, which in turn is meant to drive an immune response against cancer.

The company is also developing small molecules and antibodies aimed at cancer as well, but its Listeria-based drugs are the most advanced. CRS-207, for instance, is in a mid-stage trial in pancreatic cancer and early-stage tests in mesothelioma and ovarian cancer. In May, CRS-207 failed a trial in third-line pancreatic cancer, meaning in patients that had failed at least two prior treatments.

Aduro isn’t the only company to see a safety issue pop up while testing a Listeria-based drug against cancer. The FDA put a clinical hold on an experimental cervical cancer treatment from Advaxis (NASDAQ: ADXS), of Princeton, NJ, in September 2015 after a patient tested positive for Listeria. The hold only lasted a few months, however: Advaxis revised its study protocol and was cleared to resume testing that December.

Aduro will hold a conference call this morning to discuss the news. Shares fell just under 13 percent, to $10.70 apiece, in pre-market trading on Monday.

Here’s more on Aduro, which went public in April 2015, right after Novartis agreed to pay $250 million up front to work with the company on one of its immunotherapy approaches.