Cadisegliatin CATT1: enrollment complete, clinical effect still to be tested

October 5, 2026: 166 randomized, no Phase 3 result yet

vTv announced completion of enrollment in CATT1 with 166 participants randomized. October 5 is the announcement date; the exact last-randomization date was not supplied. This completed enrollment milestone does not mean that treatment, follow-up or analysis is complete. The company now guides topline results to mid-2027. That window is retained as guidance rather than converted to June 30 or another supposedly certain date. No Phase 3 hypoglycemia, HbA1c or safety results accompanied the announcement. [1]

Hepatic glucokinase as an adjunct to insulin

Type 1 diabetes requires exogenous insulin, but reproducing physiological glucose control with injected insulin remains difficult. Hepatic glucokinase phosphorylates glucose and supports hepatic uptake and glycogen synthesis. Cadisegliatin, formerly TTP399, is intended to activate this hepatic pathway selectively. The clinical hypothesis is improved glucose handling without an unacceptable increase in hypoglycemia or ketoacidosis. It is an adjunct to insulin, not an insulin replacement, and its study results cannot justify withdrawal of essential insulin. [1] [2]

A liver-selective mechanism is meant to differ from nonselective glucokinase activation affecting pancreatic insulin secretion. Whether that distinction produces a useful therapeutic window must be tested clinically. Oral dosing and hepatic selectivity do not themselves establish a safe glucose floor. The retrieved disclosures contain no patient-level plasma exposures or validated PK–PD threshold predicting hypoglycemia reduction. Continuous glucose monitoring, insulin requirements and clinical events are therefore essential pharmacodynamic and functional measures alongside laboratory HbA1c.

SimpliciT1: earlier controlled evidence and estimands

Part 1 of the Phase 2 program involved 19 participants using pumps and CGM. Part 2 enrolled 85 for a 12-week comparison of 800 mg once daily versus placebo on optimized insulin. The 2020 release gives enrollment, not a reconciled arm-by-arm randomized, treated and safety flow; this report does not allocate the 85 equally. Baseline HbA1c averaged 7.6%. The primary analysis reported a significant Week-12 difference, p=0.03, regardless of adherence or insulin adjustments, without the full absolute arm estimates for that analysis in the announcement. [2]

A second analysis excluded noncompliance or increases in bolus insulin of at least three units. Its placebo-adjusted HbA1c difference was −0.32 percentage points, p=0.001, from arm changes of −0.21 and +0.11. This is a different treatment-effect question: removing post-randomization deviations may change the selected population. It must not be substituted for the primary analysis merely because its p value is smaller. The complete missing-data and multiplicity strategy was not reproduced in the press release.

Time in range improved by approximately two hours relative to placebo, p=0.03. Mealtime insulin declined 11% in the active arm versus 3% with placebo; the reported p=0.02 for the active-arm reduction is not a between-group test. Background insulin adjustment, CGM adherence and endpoint definitions are necessary to interpret the apparent combination of improved HbA1c and fewer low-glucose events. These short-duration Phase 2 observations do not predict a particular magnitude of Phase 3 benefit.

CATT1 dose comparison and hypoglycemia endpoint

CATT1, NCT06334133, is randomized, double-blind and placebo-controlled in adults with Type 1 diabetes using multiple daily injections or continuous subcutaneous insulin infusion and CGM. Participants receive 800 mg once daily, 800 mg twice daily or placebo, alongside insulin, for six months. Although 166 have been randomized overall, actual arm sizes, treated populations and complete follow-up counts are not yet reported. A three-arm design is not permission to divide the total by three and label that as observed enrollment. [1] [5]

The primary endpoint evaluates Level 2 and Level 3 hypoglycemia events. Level 2 denotes clinically important biochemical hypoglycemia, whereas Level 3 involves severe impairment requiring assistance; events and affected patients are different quantities. Secondary assessments include HbA1c, time in range and ketoacidosis. The retrieved enrollment announcement does not provide the full recurrent-event model, exposure-time denominator, missing-CGM rules, multiplicity across doses or a complete estimand. These details will determine whether an apparent reduction reflects fewer events, altered observation time or both.

Clinical hold history and current safety uncertainty

The FDA lifted the clinical hold in March 2025 after the sponsor investigated a chromatographic signal and concluded it was an experimental artifact. That episode should not be rewritten as a confirmed clinical liver-injury signal. The company also described shortening the treatment period from 12 to six months; the current enrollment release uses six months. The history remains relevant to assay control and execution, but does not supply a current Phase 3 safety result. [1] [2] [3]

Phase 2 reported no ketoacidosis and fewer symptomatic-hypoglycemia patients with active treatment, but exact all-TEAE, SAE, death and withdrawal rates were not supplied in the topline release. Zero observed events in a small short study cannot exclude uncommon harm. For CATT1, such outcomes remain undisclosed. Interpretation of any later result must preserve dose-specific safety denominators and distinguish severe clinical episodes from CGM-defined low-glucose readings.

Financing and the next analysis

The August 2026 financial update reported $86.6 million of cash and equivalents at June 30, quarterly R&D expense of $8.8 million and a $13.1 million net loss. Management described resources supporting the planned readout; that projection is conditional on spending and trial execution. Enrollment completion reduces recruitment uncertainty but leaves treatment retention, data cleaning and the statistical analysis outstanding. The next clinically meaningful event is the mid-2027 results window, not an assumed approval or a new interpretation of these enrollment numbers. [1] [4]

Sources / References

1. vTv · CATT1 enrollment · October 5, 2026
2. vTv · SimpliciT1 Part 2 · February 10, 2020
3. vTv · clinical hold lifted · March 14, 2025
4. vTv · Q2 results · August 6, 2026
5. ClinicalTrials.gov · CATT1