- Aduro Biotech shares fell sharply after the California-based company reported the Food and Drug Administration had placed a partial clinical hold on all trials involving its listeria-based immunotherapy construct (LADD) platform.
- New patient enrollment will be halted for the time being due to new concerns over listeria infections related to Aduro's platform. A blood culture sample from one pancreatic cancer patient in an Aduro study tested positive for listeria, prompting the partial hold.
- Aduro said the listeria is suspected to be CRS-207, the company's lead LADD compound, and noted the patient has recovered after receiving intravenous antibiotics.
Aduro stock has already shed a significant amount of value so far this year, dropping roughly two-thirds from levels seen at the end of last year.
Matters weren't helped in May, when a Phase 2b trial testing Aduro's CRS-207 compound in combination with the pancreatic cancer vaccine GVAX Pancreas failed to show benefit over either standard chemotherapy or monotherapy.
Aduro said it is working with the FDA to lift the hold and resume patient enrollment. The company is in the process of revising its study protocols and beefing up patient surveillance, as well as excluded patients who have received immune-suppressive treatments. Those revisions will be submitted to the FDA later this week, Aduro said.
The company's LADD technology deletes two genes in the listeria mononcytogenes bacteria, which are then genetically engineered to express specific tumor antigens to help stimulate an immune response in patients.
Aduro's process is designed to attenuate the bacteria's virulence, but this isn't the first time the company has had issues with listeria infections cropping up. In a regulatory filing last fall, Aduro disclosed a case of listeriosis in the trial testing CRS-207 with GVAX Pancreas. The positive test for listeria was determined to be CRS-207.
Neither of Aduro's other platform technologies, STING pathway activators or B-select monoclonal antibodies, are affected by the partial hold.
While Aduro appears to be moving quickly to address the new concerns, continued trouble with listeria infections could hurt further development going forward.