While a COVID-19 patent battle with Pfizer rumbles on, Enanta Pharmaceuticals has hit pause on development of a dual inhibitor for human metapneumovirus and respiratory syncytial virus (RSV) in an effort to pave a cash runway into 2027.
The Watertown, Massachusetts-based biotech had been working on ways to target both viruses with a single agent. After noting that its prototype induced a significant reduction in the viral load of each virus in mouse models, Enanta had previously expected to select a clinical candidate in the fourth quarter of the year.
But, in a third-quarter earnings release, the biotech announced the research program has been paused. Despite “promising preclinical data,” Enanta no longer plans to take any more RSV candidates into the clinic while two others are in development.
Those remaining candidates in question, EDP-938 and EDP-323, form the centerpiece of Enanta’s slightly updated strategy.
EDP-938, an N-protein inhibitor, is in two phase 2 trials for pediatric and adult patients with RSV, respectively. Assuming a typical RSV season in the Northern Hemisphere, Enanta is expecting to complete enrollment of one or both of the studies by the third quarter of 2024.
The company discontinued another midstage study of EDP-938 in September, this time in adult hematopoietic cell transplant recipients with RSV infection and symptoms of upper respiratory tract infection, according to yesterday’s release. This marks the latest speed bump for the candidate, which already failed a phase 2b trial in low-risk RSV patients last year.
Enanta’s other RSV candidate is an L-protein inhibitor called EDP-323, which the company announced in the same release has now entered a phase 2 trial. Initial data are due in the third quarter of next year.
“We have … made important adjustments to significantly reduce our 2024 spending and extend our cash runway through fiscal 2027,” CEO Jay Luly, Ph.D., said in the earnings release. “As a result, we are well positioned financially as we look forward to readouts across our RSV pipeline in 2024 and advancements in new non-virology programs.”
In the wake of mixed data from the COVID-19 drug EDP-235 back in May—which showed the antiviral reduced some symptoms but did not lower viral load or time to improvement—the biotech announced that it would only pursue the asset if a partner was secured. Based on yesterday’s release, the hunt for a collaborator remains ongoing.
Despite its own COVID-19 work having stalled for now, Enanta’s patent infringement case against Pfizer remains ongoing. The biotech filed the suit in the U.S. district court in Massachusetts last year claiming (PDF) that the pharma giant had infringed a patent for Enanta's protease inhibitor COVID drug in creating the blockbuster antiviral Paxlovid.
Enanta attributed a $1.2 million year-over-year rise in its general and administrative fees for the third quarter of 2023 to an increase in legal fees related to the case.