CT-388 delivered 22.5% placebo-adjusted weight loss in Phase 2, the highest ever recorded in a controlled weight loss trial. 54% of participants reached a healthy BMI. Phase 3 ENITH1 and ENITH2 are now underway.
Phase 2: 22.5% placebo-adjusted weight loss, the highest ever recorded in a controlled trial. 54% of participants reached a healthy BMI. Phase 3 is now underway.
A weekly dual agonist that produced the highest placebo-adjusted weight loss ever recorded in a trial. CT-388 is Roche and Genentech's entry into the GLP-1/GIP dual agonist class, and its Phase 2 results set a new benchmark.
CT-388 works similarly to Zepbound (tirzepatide), it's a dual agonist targeting both the GLP-1 and GIP receptors simultaneously. But the results in Phase 2 were markedly stronger than anything tirzepatide produced: a 22.5% placebo-adjusted weight loss and an 18.3% loss on the treatment regimen at 48 weeks, with no plateau observed.
To put 22.5% placebo-adjusted in context: that number strips out the effect of the diet and lifestyle program participants also followed, isolating only the drug's contribution. It's the highest drug-specific weight loss number ever measured in a controlled clinical trial. 54% of participants reached a BMI under 30, and 47.8% lost 20% or more of their body weight.
Phase 3 trials ENITH1 and ENITH2 started in Q1 2026. Roche and Genentech are moving fast, this is one of the most closely watched drugs in the obesity pipeline.
Targets GLP-1 and GIP simultaneously. Both reduce hunger, from different angles. CT-388 activates both GLP-1 and GIP receptors, producing synergistic appetite suppression and metabolic effects that go beyond either target alone.
CT-388 is administered once a week as a small subcutaneous injection, similar to other GLP-1 class drugs. The dose is gradually escalated over several months to minimize gastrointestinal side effects during the adjustment period.
GLP-1 and GIP receptor activation work together to dramatically reduce hunger. In Phase 2, 95.7% of participants lost at least 5% of their body weight, a remarkably consistent response across the trial population.
CT-388's Phase 2 results showed no weight loss plateau at 48 weeks. Like MariTide, the weight loss curve was still declining at the end of the observation period, suggesting peak effectiveness hasn't been reached yet at 48 weeks.
Phase 2 data announced January 2026: 22.5% placebo-adjusted, 18.3% treatment-regimen, no plateau at 48 weeks. Roche and Genentech announced Phase 2 results in January 2026. The data, including a 22.5% placebo-adjusted weight loss, set new records for the class and immediately positioned CT-388 as one of the most potent obesity drugs ever tested.
47.8% of participants lost 20% or more of their body weight. 95.7% lost at least 5%. No weight loss plateau was observed at 48 weeks. To put 22.5% placebo-adjusted in context: Wegovy shows roughly 12% placebo-adjusted, and tirzepatide (Zepbound) shows around 17-18%. CT-388's 22.5% represents a meaningful step beyond the best currently approved drug.
Phase 3 ENITH1 and ENITH2 are underway. FDA decision expected 2028-2029. After Phase 2 results in January 2026 that outperformed the field, Roche moved quickly into Phase 3. The full development roadmap below.
Phase 3 ENITH trials are now enrolling. You would receive CT-388 at no cost under close medical supervision throughout the study.
Search Open Trials →"Most of the pipeline drugs I see are incremental improvements. CT-388 is one of the few where the phase 2 data made me actually curious about what phase 3 is going to look like. That doesn't happen often."
Dr. Humberto Fernandez-Miro, MD
Family Medicine · Clinical Research
Not available yet. Here's who it looks best suited for when it is. CT-388 isn't approved yet. Based on Phase 2 data and ongoing Phase 3 trials, here's who this drug looks most promising for, and what to weigh before deciding to wait for it.
CT-388 vs. current and upcoming weight loss drugs, by the numbers. CT-388's Phase 2 results outperformed everything else in the class on placebo-adjusted weight loss. A direct look at where it lands.
| Drug | Mechanism | Best Weight Loss | Dosing | Status |
|---|---|---|---|---|
| 💉CT-388 | GLP-1 + GIP Dual Agonist | 22.5% (placebo-adj.) / 18.3% | Weekly | Phase 3 |
| 💉Wegovy | GLP-1 Agonist | 15% | Weekly | FDA Approved |
| 💉Zepbound | GLP-1 + GIP Agonist | 20-21% | Weekly | FDA Approved |
| 💉Retatrutide | GLP-1 + GIP + Glucagon | 24.2% | Weekly | Phase 3 |
| 💉MariTide | GIP Antagonist + GLP-1 | 16.2% (no plateau) | Monthly | Phase 3 |
CT-388's 22.5% is placebo-adjusted (drug effect isolated from lifestyle intervention). Retatrutide's 24.2% is the total treatment-regimen number. Direct comparisons between drugs are not available. All figures from published Phase 2/3 trial data.