Aduro Biotech ($ADRO) has a trio of engineered immunotherapy platforms. Its lead is known as LADD, which is based on live, attenuated, double-deleted Listeria monocytogenes. That gene deletion process is intended to destroy the natural virulence of the Listeria bacteria.
But now, Aduro is subject to a partial hold on its LADD-based clinical trials after two patients tested positive for Listeria. The most recent was a metastatic pancreatic cancer patient, who presented with gastrointestinal symptoms. After a positive Listeria test, the patient was treated with intravenous antibiotics and subsequently tested negative for the disease.
The company said that this is the second Listeria case from more than 350 tested patients, both of which were related to in-dwelling medical device ports where a biofilm can form. Preliminary testing indicates that the biofilm is related to CRS-207, which is the candidate that was being tested in the Phase II metastatic pancreatic cancer trial. That trial had been enrolling and is expected to reach about 102 patients.
“We continue to believe the risk/benefit equation makes sense for cancer patients,” said Aduro chairman, president and CEO Stephen Isaacs on a conference call regarding the partial hold.
Three additional ongoing clinical trials are affected by the partial hold: a Phase I/II study for CRS-207 in combination with Incyte’s ($INCY) IDO-inhibitor epacadostat to treat ovarian cancer; a Phase I lung cancer trial by partner Janssen Biotech ($JNJ) to develop partnered candidate ADU-214; and a Phase I trial of ADU-623 to treat high-grade glioma by outside investigators at the Earle Chiles Research Institute at Providence Cancer Center in Portland, OR.
The Berkeley, CA-based biotech is working with the FDA to lift the partial hold, which has paused any new patient enrollment, revising its study protocols based on agency feedback. These include “the modification of antibiotic administration following treatment, extended patient surveillance, and, as a pre-emptive measure, exclusion of patients who are on or will receive certain immune-suppressive treatments or who have certain prosthetic devices,” the company said in a statement.
Aduro said it expects to submit revised protocols, patient consent forms and investigator brochures to the FDA later this week. The company said the partial hold doesn't have any implications for the candidates from its two other platforms: STING pathway activators and B-select monoclonal antibodies.
Existing patients in the LADD-based clinical trials will continue to receive the candidates, except for one patient who has a pacemaker. Several of these patients have already been on the study drug for six months or longer.
Earlier this year, Aduro reported a Phase IIb trial failure for CRS-207 in combination with GVAX to treat pancreatic cancer.
Aduro went public almost exactly a year ago in a $119 million IPO at $17 per share. It dropped about 8% on the Listeria news to a share price of about $11 and a market cap of around $730 million.