SURMOUNT-ADOLESCENTS-2 begins with a comorbidity-resolution endpoint

Eli Lilly has begun a second phase 3 trial of tirzepatide in adolescents with obesity, called SURMOUNT-ADOLESCENTS-2, registered on ClinicalTrials.gov under identifier NCT06439277 ^[1]. The study plans to enroll 300 participants ages 12 to 17 who have obesity along with multiple weight-related health conditions ^[1]. Lilly sells tirzepatide as Zepbound for weight management and as Mounjaro for type 2 diabetes in adults; this trial extends that drug's development program into a younger age group ^[1].

The study's design goes beyond measuring weight loss alone. Alongside the standard endpoint of percent change in body mass index at week 72, the trial has a co-primary composite endpoint that requires participants to show normalization or a clinically meaningful improvement in at least two predefined weight-related comorbidities, without developing any new ones, by the same 72-week mark ^[1]. This means researchers are tracking not just how much weight participants lose, but whether conditions tied to that weight, such as markers of blood sugar, blood pressure, or other measures common in obesity, actually get better or resolve.

The trial's primary completion date is listed as October 2027 ^[1]. That timeline reflects the multi-year follow-up needed to assess both the BMI endpoint and the comorbidity composite endpoint at week 72, plus the administrative time to collect and lock the data before it can be reported ^[1].

This is described as a second trial in the SURMOUNT-ADOLESCENTS program, suggesting Lilly is running more than one phase 3 study of tirzepatide in this age group, though the ClinicalTrials.gov record does not detail how this trial's design differs from or relates to results of the first one ^[1].

Why it matters for patients

For families considering GLP-1 or dual GLP-1/GIP therapy for a teenager, this trial's design signals that regulators and researchers may be looking for more than a number on a scale before broadening approval of these drugs to include younger patients with obesity-related health problems. The comorbidity-resolution endpoint means the trial is set up to show whether tirzepatide can meaningfully improve or normalize conditions like those tied to blood sugar or blood pressure in adolescents, not just reduce BMI ^[1].

Because the trial requires improvement in at least two comorbidities without any new ones appearing, the bar for success in this study is defined narrowly and specifically. Parents and clinicians watching this space should know that results describing whether tirzepatide meets this bar in teenagers are not yet available and will not be known until after the trial's primary completion date ^[1].

It is not yet known from the available record how this second adolescent trial differs in dosing, comparator arm, or population from any earlier phase 3 adolescent study Lilly may have run, nor is it known what specific comorbidities are on the predefined list for the composite endpoint ^[1]. Families and clinicians will need to wait for further disclosures, such as a detailed protocol or results publication, to learn those specifics.

What happens next

The trial's primary completion date is listed as October 2027, the point at which the main BMI and comorbidity outcome data are expected to be collected ^[1]. Enrollment of the full 300 participants and the 72-week treatment and follow-up period will need to occur before that data can be analyzed and reported ^[1]. No results, interim or final, are available in the current source record.