Vaccine failure blows a hole in Pfizer's pipeline

Burying the failure of a trial in bullet point number four of a press release is not typically a big pharma strategy. But perhaps desperate times call for desperate measures: Pfizer’s C difficile vaccine is considered one of its most valuable development projects, and the group is under pressure to beef up its pipeline. True, hopes had dimmed after the pandemic threatened to derail the 17,500-patient Clover trial, and Glaxo’s competing, earlier-stage programme ran into similar problems. Clover was designed on an assumption of 66 C diff cases within two years, but in the end Pfizer had to run the final analysis after 42 cases within four years of vaccination. No p values were disclosed for the two primary vaccine efficacy endpoints, but these yielded wide confidence intervals and must have failed by a considerable margin. And while the company highlighted secondary endpoints that appear to point to a reduction in severe disease and disease duration, regulators will surely struggle to consider those findings rigorous. Regulatory opinions will be sought, Pfizer said. Perhaps significant unmet need, previous failures that have demonstrated how tough this setting is, and a thin pipeline coming behind will act in the company’s favour.