Stoke Therapeutics: The Long Game on Zorevunersen's OLE Data

How longitudinal data and a de-risked Phase III set the stage for a potential Dravet franchise.

STOK · Earnings Call · 2026-08-03

The Quiet Confidence of a Fully Enrolled Phase III

Stoke Therapeutics reported its second quarter update on August 3, 2026, and the tone was one of controlled optimism. The company's lead asset, zorevunersen, an antisense oligonucleotide for Dravet syndrome, has completed enrollment of 162 patients in the Phase III EMPEROR study in just 10 months — a pace that speaks to the unmet need and the physicians' enthusiasm. More importantly, there have been zero treatment discontinuations to date. As CEO Ian Smith noted, “We are now within 1 year of our Phase III readout to data that would support the completion of our NDA.” — Ian Smith, Chief Executive Officer · 2026-08-03 This progress is not just about velocity; it directly addresses statistical powering. The study was originally powered for 150 patients with a 15% discontinuation assumption. With 162 enrolled and no dropouts, EMPEROR study is now over-powered for its primary endpoint and even more so for the key secondary endpoints measured by Vineland-3.

The OLE Data: The Real Story

The most compelling narrative shift this quarter is the elevated role of the open-label extension (OLE) data. While the Phase III readout is still a year away, management is already positioning the longitudinal dataset as a critical component of both the NDA and commercial value proposition. Chief Medical Officer Barry Ticho emphasized that “More than 930 doses of zorevunersen have been administered to date, with some patients receiving treatment for more than 5 years.” — Barry Ticho, Chief Medical Officer · 2026-08-03 These data, published in the New England Journal of Medicine, are being used to educate payers and prescribers about the potential for disease modification. Commercial lead Jason Hoitt explained that in recent market research, the long-term OLE data were the most compelling evidence for both payers and healthcare providers. This is particularly relevant as the company seeks a broad label. The OLE data will be part of the pre-NDA meeting with the FDA, and management expects to have approximately 6 years of safety and efficacy data at submission. The focus on Vineland scores as a measure of cognitive and behavioral gains is a differentiator, as Dravet is not just a seizure disorder. Ian Smith articulated this powerfully:

We appear to be providing benefit where we're giving them function and giving them skill... they can barely talk and have a minimal number of words they can use; we're providing the ability to many more words, to actually use sentences.
Ian Smith, Chief Executive Officer · 2026-08-03

This communication-centric benefit is exactly what payers want to see for a disease-modifying therapy.

Commercial Readiness and Financial Runway

The company is not waiting for the Phase III readout to build commercial infrastructure. With an estimated 16,000 US Dravet patients, of which approximately 6,000 are under 25 and immediately addressable, Stoke plans to launch with a lean sales force of about 25 reps targeting the top 50 treatment centers. Jason Hoitt noted that half of these centers are already participating in a zorevunersen trial, providing a foundation for early adoption. “The data to be included in the label are going to be most important for promotional purposes.” — Jason Hoitt, Commercial Leader · 2026-08-03 The company also expects to initiate a study in adults and one in infants/toddlers under 24 months later this year. Financially, Stoke ended the quarter with $354.3 million in cash and subsequently raised $65.7 million, bringing pro forma cash to about $420 million. This is expected to fund operations through a potential US launch in early 2028. However, the financial trajectory shows heavy investment: R&D expenses rose 21% year-over-year to $40 million in Q2, while revenue remained nominal. R&D expense grew from $22 million in 2024 to $40 million in the latest quarter, reflecting the late-stage study and commercial preparation. Beyond Dravet, the ADOA program is advancing. The Phase I study has completed dosing the first cohort of 3 patients and moved to a second higher-dose cohort. Early safety and efficacy results are expected in the first half of 2027. This program, along with SYNGAP1 and other haploinsufficiency targets, leverages the same platform, providing multiple shots on goal.

What Changed This Quarter?

The key change is the explicit de-risking of the Phase III program and the strategic elevation of the OLE dataset. The company is no longer just a development-stage biotech; it is actively planning for launch and building evidence for reimbursement. The unqualified confidence in the secondary endpoints, the zero discontinuation rate, and the strength of the longitudinal data collectively suggest that the market's attention should shift from binary Phase III risk to the nuances of label and pricing. The company's own keyword trajectory reflects this pivot, with terms like Phase I/II and "OLE data" dominating the conversation — a shift from earlier quarters focused on early clinical results. For investors, the next catalysts are the pre-NDA meeting in the fall, the initiation of the rolling submission in Q1 2027, and the final data readout in Q3 2027.