Market reaction and overview
Shares of Invivyd Inc. (NASDAQ:IVVD) jumped 24.8% Thursday following company updates on its COVID-19 prevention candidate VYD2311 and the disclosure of a newly discovered measles antibody candidate. The moves reflect clinical- and regulatory-related milestones that management says strengthen study power and broaden the pipeline.
DECLARATION study - sample size re-estimation and timeline
Invivyd reported that pooled, blinded COVID-19 events accrued so far in its ongoing Phase 3 DECLARATION study are already sufficient to provide statistical power consistent with the high end of the company’s anticipated VYD2311 efficacy, even though the trial is approximately 50% complete.
The company carried out a pre-specified sample size re-estimation analysis on April 6 when 1,500 of the 1,818 enrolled participants had reached Day 45 of the study’s 90-day follow-up period. That analysis triggered an upsizing of the trial population, a step Invivyd said increases confidence in the overall study statistical power.
As a result, the DECLARATION study will enroll roughly 500 additional subjects beyond the initial 1,818 randomized participants. Management indicated that the upsizing is likely to delay the timing of top-line results by roughly two months, moving expected readout from original mid-year guidance into the third quarter of 2026.
Pediatric plan tied to pivotal DRUMMER trial
Invivyd also announced that it has aligned with the U.S. Food and Drug Administration on an initial Pediatric Study Plan. The plan relates to a BLA-directed pivotal pediatric immunobridging and safety trial, named DRUMMER, intended to evaluate VYD2311 in children aged 0-11 years should the DECLARATION study demonstrate success.
New measles antibody - VMS063
Separately, the company revealed the discovery of VMS063, a novel monoclonal antibody candidate for measles treatment and prevention. Invivyd has initiated IND-enablement activities and regulatory outreach aimed at supporting accelerated development, targeting IND readiness in late 2026.
According to the company, VMS063 shows highly potent in vitro neutralization of measles virus across relevant lineages, including currently circulating B3 and D8 as well as the ancestral Edmonston lineage. The antibody is half-life extended and binds the measles Fusion protein.
What remains uncertain
Key elements that remain conditional on future results include the final efficacy readout from the DECLARATION study and the outcome of regulatory engagement and IND-enablement for VMS063. The pediatric DRUMMER trial is contingent on a successful DECLARATION outcome.
Investors and market participants will be watching the enlarged DECLARATION dataset, subsequent timing for top-line data in Q3 2026, and regulatory progress for both the pediatric program and the measles antibody IND-enablement.