John McHutchison throws in the towel on HBV drug, triggering layoffs as Assembly shifts to next-gen approaches
When Assembly Biosciences disclosed in 2020 that its lead experimental hepatitis B drug vebicorvir, in combination with nucleoside therapy, couldn’t offer the functional cure it was looking for, the biotech pinned hopes on a triple-drug concoction containing an RNAi therapeutic from Arbutus Biopharma.
Two years later, Assembly Bio said it’s shelving vebicorvir altogether — and laying off 30% of staffers as it regroups. As part of the restructuring, the CMO and CFO will exit the company.
The decision to discontinue clinical development of vebicorvir (dubbed VBR internally) follows an interim review of two separate triplet trials suggesting that neither VBR combos show signs of efficacy, as measured by multiple viral parameters.
“By combining VBR with NrtI therapy, we achieved a more rapid and a deeper level of viral suppression than with NrtI alone and we have continued to see a favorable safety and tolerability profile for VBR,” CEO John McHutchison said in a statement. “Unfortunately, we do not believe, based on the interim data from our current studies, that either VBR triple combination is likely to achieve a meaningful rate of functional cure for patients with chronic HBV infection.”
Arbutus, though, doesn’t quite share the same belief.
“While we respect Assembly’s decision to discontinue clinical development of VBR, we believe that it is premature to make any conclusions about any results in this triple combination clinical trial,” Arbutus CEO William Collier said in a separate release, referring to the study that involved his company’s drug. “We intend, in collaboration with Assembly, to continue the clinical trial in order to fully and accurately assess the results.”
So as Assembly shuts the door to future trials and wraps Study 203 — a Phase II study testing VBR plus NrtI (nucleoside analogue reverse transcriptase inhibitor) plus interferon — Study 204 will go on, with primary endpoints being safety and tolerability.
Patients are given either VBR, NrtI and Arbutus’ AB-729, VBR plus NrtI, or NrtI plus AB-729. The RNAi drug is designed to reduce all HBV viral proteins and antigens.
For Assembly Bio, the focus now shifts to two next-generation core inhibitors that it hopes could prove potent treatments for HBV. At the same time, it’s also working on earlier-stage research programs, including a hepatitis D virus entry inhibitor, a liver-focused interferon-α receptor agonist and new antivirals to be introduced later.
With CMO Luisa Stamm and CFO Michael Samar set to leave in the next few weeks, McHutchison — a former Gilead CSO — will now lead a remaining team of 70.
Meanwhile, Michele Anderson, SVP of development operations, is being promoted to chief development officer; and COO Jason Okazaki will add president to his title and finance to his slate of duties. The company now expects to have a cash runway into the first half of 2024.