The FDA has placed a partial clinical hold on a Phase III PD-L1 candidate from AstraZeneca due to bleeding adverse events in two clinical trials. It restricts the pharma from adding new patients to clinical trials for its durvalumab, as monotherapy and in combination, in head and neck squamous cell carcinoma (HNSCC).
The candidate, previously known as MEDI4736, is partnered with Celgene ($CELG) under a pair of hematology deals it did with AstraZeneca last year that are worth up to $1.8 billion. In fact, Celgene paid $540 million upfront specifically tied to durvalumab and agreed to cover three-quarters of related clinical trial costs through the end of this year. The candidate originated under an AstraZeneca deal with Abgenix that dates back to 2003.
In February, durvalumab won breakthrough therapy designation from the FDA to treat urothelial bladder cancer.
Prior to the partial clinical hold from the FDA, AstraZeneca said it opted to pause new patient enrollment in the HNSCC indication after adverse bleeding events were observed in two Phase III trials: KESTREL and EAGLE. AstraZeneca said that trials in other cancer types are progressing, with pivotal lung cancer data anticipated during the first half of 2017.
The company cautioned that bleeding can be a common complication in HNSCC patients given the nature of the underlying disease, the proximity of tumors to major blood vessels and the use of prior therapies, in addition to surgery and radiation.
AstraZeneca said it has already submitted an analysis of the observed bleeding events to the FDA and that it is working with the agency to resume new patient enrollment.
The only FDA-approved PD-L1 inhibitor is Roche’s Tecentriq (atezolizumab), which gained approval in May to treat urothelial bladder cancer.
The data from KESTREL was slated to be due during the second half of 2017, while EAGLE was intended to report in 2018.
AstraZeneca shares were down about 4% in early trading on the news, while immuno-oncology competitor Bristol-Myers Squibb ($BMY), which also reported earnings, was up about 6%.
Editor's note: This article was updated to correct information on the origins of durvalumab.