Vitalis Therapeutics Inc. — A program-management summary of the VitaFlow (VTX-401) pivotal protocols: two registration trials totalling 2,480 participants over 68 weeks, plus a nested cardiovascular sub-study. Enrolment position as at 15 October 2026.
1. What This Document Is
A program-management summary of the VitaFlow (VTX-401) pivotal protocols. It is not the protocol. The protocol is authored by clinical development and biostatistics and runs to several hundred pages; this document extracts what a sponsor program manager has to understand in order to manage the study.
2. The Pivotal Program
| Study | Design | Randomization | N | Sites | Duration |
|---|---|---|---|---|---|
| VTX-401-301 | Randomized, double-blind, placebo-controlled, parallel-group | VTX-401 / placebo, 2:1 | 1,360 | 142 | 68 wk |
| VTX-401-302 | Randomized, double-blind, active- and placebo-controlled, parallel-group | VTX-401 / active comparator / placebo, 2:2:1 | 1,120 | 118 | 68 wk |
| VTX-401-303 | Cardiovascular outcomes sub-study with independent adjudication (CR-02) | Nested within 301 and 302 | 640 | 64 | 68 wk |
Registration rests on VTX-401-301 and VTX-401-302 — 2,480 participants across two adequate and well-controlled trials. VTX-401-303 is nested within them and supports safety, not efficacy.
Why two pivotals and not one
A single trial can support approval and often does. Two were chosen here for a specific reason: the differentiation claim is tolerability, and tolerability is a secondary endpoint that will be contested. A result replicated across two independently randomized populations is substantially harder to attribute to chance or to a single site network's characteristics than the same result from one trial, however large.
The cost of that choice is visible in the Program Budget: the pivotal program is $109,100,000, 50% of the base program. A single-trial design would have been materially cheaper and would have supported a weaker claim.
Why 302 carries an active comparator
The comparator arm in VTX-401-302 is Decision D-08, and it exists for market access rather than for registration. Approval requires superiority over placebo; reimbursement increasingly requires a view on relative effectiveness against what a payer is already funding. Generating that evidence inside the pivotal program is far cheaper than running a separate head-to-head study post-approval, and it means the payer conversation at launch is supported by data rather than by indirect comparison.
3. Population & Eligibility
Adults, BMI ≥30, or ≥27 with ≥1 weight-related comorbidity.
Inclusion
- Adults aged 18 years or older
- BMI ≥30 kg/m², or ≥27 kg/m² with at least one weight-related comorbidity
- At least one documented unsuccessful dietary weight-loss attempt
- Stable body weight (<5% change) in the 90 days before screening
Exclusion
- Type 1 or type 2 diabetes mellitus
- HbA1c ≥6.5% at screening
- Personal or family history of medullary thyroid carcinoma or MEN2
- History of pancreatitis
- Prior or current GLP-1 receptor agonist exposure within 90 days
- Bariatric surgery within 5 years, or planned during the study
- Major cardiovascular event within 180 days
- Pregnancy, lactation, or intention to conceive during the study
The prior-GLP-1-exposure washout is the one with room in it, and it is the one causing the most screen failures in a market where GLP-1 use is now widespread. Extending the washout would worsen recruitment; shortening it risks carry-over effect on the primary endpoint. The protocol holds at 90 days and the program absorbs the recruitment cost.
4. Endpoints
| Tier | Endpoint | Test |
|---|---|---|
| Co-primary | Percent change in body weight, baseline to week 68 | Superiority vs placebo |
| Co-primary | Proportion achieving ≥5% weight reduction at week 68 | Superiority vs placebo |
| Key secondary 1 | Proportion achieving ≥10% weight reduction at week 68 | Hierarchical |
| Key secondary 2 | Proportion achieving ≥15% weight reduction at week 68 | Hierarchical |
| Key secondary 3 | Change in waist circumference at week 68 | Hierarchical |
| Key secondary 4 | Discontinuation attributable to gastrointestinal adverse events | Hierarchical — the differentiation endpoint |
| Safety | Treatment-emergent adverse events, laboratory, vital signs, ECG | Descriptive |
| Sub-study | Time to first adjudicated major adverse cardiovascular event | Non-inferiority, HR upper bound <1.4 |
That places the GI-attributed discontinuation endpoint fourth in the hierarchy, behind three weight-reduction endpoints. It is the program's differentiation claim sitting behind three tests it must first pass. This was argued at protocol finalisation and the position lost: the agency's expectations for the indication drive the weight endpoints to the top, and reordering to protect a commercial claim would have been visible as exactly that.
Endpoint definitions and the testing order were agreed at the End-of-Phase-2 meeting of 19 May 2026 and are recorded as must-meet criterion M2 at Gate 4. Changing either now would require a new agency interaction, which is why endpoints sit in the “cannot change” category at §1.
5. Statistical Design
| Parameter | Value |
|---|---|
| Power | 90% for both co-primary endpoints |
| Significance level | 0.05, two-sided |
| Estimand | Treatment policy — effects regardless of adherence, intention-to-treat |
| Missing data | Multiple imputation under a retrieved-dropout assumption; tipping-point sensitivity |
| Interim analysis | One interim futility analysis at 50% of participants completing week 24, reviewed by the DMC only. No efficacy stopping boundary. |
The futility look protects participants and capital. The absence of an efficacy boundary protects the filing.
The estimand is a treatment-policy estimand: the analysis measures effects regardless of whether participants stayed on treatment. On a therapy whose principal risk is discontinuation for tolerability, an on-treatment estimand would systematically flatter the result by analysing out the people the drug failed.
6. Enrolment Position — 15 October 2026
| Measure | Value | Note |
|---|---|---|
| Sites planned | 260 | |
| Sites activated | 231 | 89% of plan |
| Sites enrolling | 214 | 17 activated but not yet randomizing |
| Screened | 2,910 | |
| Screen failures | 1,142 | 40% of completed screening — mid-range against the published 20–80% span |
| Randomized | 1,684 | 68% of the 2,480 target |
| Planned to date | 1,760 | 76 behind curve (96%) |
The screen-failure rate of 40% is unremarkable — published rates span 20% to 80% and this sits mid-range. More to the point, it is not improving fast enough to matter: the two largest causes are the GLP-1 washout and the diabetes exclusion, and neither can be relaxed without damaging the endpoint. Screening is not where the recovery comes from.
It is a site problem. 17 sites are activated but have not randomized anyone, and 29 of the planned 260 are not activated at all. Published benchmarks put site non-activation at around 11% and this program is at 18% on the harsher measure of sites not yet enrolling. Recovery therefore runs through site activation and the reserve list, not through loosening criteria.
Detailed tracking, per-site performance and the recovery plan live in the Enrolment & Site Dashboard and the Site Selection & Management Plan.
7. What Is Schedule-Critical, Cost-Critical, or Fixed
The three categories from §1, applied.
| Design element | Category | Consequence |
|---|---|---|
| Co-primary endpoints and testing hierarchy | Fixed | Agreed at End-of-Phase-2. Any change requires a new agency interaction and reopens Gate 4 must-meet M2. |
| 68-week treatment duration | Fixed | Convention for the indication. Shortening it would not support the label. |
| Diabetes and HbA1c exclusions | Fixed | Design integrity — the indication cannot be confounded by glycaemic effect. |
| Site count and activation sequence | Schedule-critical | The binding constraint on last-patient-in, and therefore on database lock and the Gate 5 filing date. |
| Prior-GLP-1 washout period | Schedule-critical | Drives screen failure in a market with widespread GLP-1 use. Held at 90 days. |
| Number of pivotal trials | Cost-critical | Two trials rather than one is most of the $109,100,000 pivotal cost. |
| Active comparator arm (D-08) | Cost-critical | Adds cost, supports market access rather than registration. Removable without regulatory consequence — and would weaken the payer position at launch. |
| Cardiovascular sub-study (CR-02) | Cost-critical | $7,200,000 from contingency. Pre-empts a post-marketing requirement. |
8. Safety Oversight
An independent Data Monitoring Committee reviews unblinded safety data on a every 16 weeks, and ad hoc on request of any member basis.
| Member | Discipline | Blinding |
|---|---|---|
| Prof. E. Vartanian | Chair — endocrinology | Independent |
| Dr. L. Okafor | Cardiology | Independent |
| Dr. S. Brennan-Hale | Hepatology | Independent |
| Prof. M. Iwasaki | Independent statistician | Unblinded |
Independent statistician only; sponsor personnel remain blinded. Recommendations to pause, modify or stop are binding on the sponsor (C-05).
Full composition, review procedures, stopping guidance and the communication protocol are in the Data Monitoring Committee Charter.