NCT02137538

Aromatase Inhibitor Growth Study: Letrozole vs. Anastrozole

Completed Phase 4 Results posted Last updated 15 July 2021

What this trial tests

Phase 4 trial testing Letrozole in Short Stature in 79 participants. Completed in 5 June 2018.

Timeline

18 November 2009

Primary endpoint
5 June 2018

5 June 2018

Quick facts

Lead sponsor	Stanford University
Phase	Phase 4
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	none
Primary purpose	treatment
Enrollment	79
Start date	18 November 2009
Primary completion	5 June 2018
Estimated completion	5 June 2018
Sites	1 location across United States

Drugs / interventions tested

• Letrozole — full drug profile →
• Anastrozole (anastrozole) — full drug profile →

Conditions studied

• Short Stature — all drugs for Short Stature →

Sponsor

Stanford University

Who can join

Adults 10 to 17, male only, with Short Stature. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Predicted Adult Height at Year 3 Primary · Year 3

Heights will be obtained by physical exam every 6 months during treatment. Skeletal maturation will be assessed from an x-ray by the method of Greulich and Pyle at baseline and every 12 months until the end of treatment. Predicted adult height will be calculated at baseline and at the end of treatment based upon measured height and skeletal maturation (bone age).

Group	Value	95% CI
Letrozole	167.8	± 5.8
Anastrozole	169.4	± 5.1

Serum Testosterone Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	213.1	± 133.7
Anastrozole	162.1	± 124.6

Year 3

Group	Value	95% CI
Letrozole	882.3	± 250.5
Anastrozole	680.1	± 179.5

Dihydrotestosterone Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	22.5	± 11.3
Anastrozole	19.1	± 9.7

Year 3

Group	Value	95% CI
Letrozole	65.0	± 20.2
Anastrozole	44.1	± 23.5

Androstenedione Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	35.3	± 13.1
Anastrozole	37.4	± 21.4

Year 3

Group	Value	95% CI
Letrozole	79.9	± 21.5
Anastrozole	77.9	± 28.2

Luteinizing Hormone Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	2.3	± 1.5
Anastrozole	1.8	± 1.1

Year 3

Group	Value	95% CI
Letrozole	4.7	± 1.9
Anastrozole	3.4	± 2.0

Follicle Stimulating Hormone Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	3.3	± 1.9
Anastrozole	2.5	± 1.3

Year 3

Group	Value	95% CI
Letrozole	6.6	± 2.4
Anastrozole	4.5	± 2.9

Insulin-like Growth Factor Type 1 Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	306.2	± 112.8
Anastrozole	306.9	± 112.9

Year 3

Group	Value	95% CI
Letrozole	226.1	± 54.4
Anastrozole	298.7	± 78.8

Inhibin B Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	203.4	± 55.0
Anastrozole	217.0	± 65.2

Year 3

Group	Value	95% CI
Letrozole	257.6	± 61.1
Anastrozole	262.1	± 97.9

Estradiol Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	4.9	± 3.6
Anastrozole	4.7	± 4.7

Year 3

Group	Value	95% CI
Letrozole	2.7	± 2.1
Anastrozole	6.2	± 2.5

Estrone Secondary · Baseline, year 3

Baseline

Group	Value	95% CI
Letrozole	8.7	± 4.8
Anastrozole	8.0	± 4.9

Year 3

Group	Value	95% CI
Letrozole	2.7	± 0.3
Anastrozole	3.5	± 3.2

Number of Adverse Events Related to Acne or Bone Fracture Secondary · 3 years

Acne

Group	Value	95% CI
Letrozole	3
Anastrozole	3

Fracture

Group	Value	95% CI
Letrozole	3
Anastrozole	5

Adverse events — posted to ClinicalTrials.gov

Time frame: 3 years. Reporting threshold: 0%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

Letrozole

Serious: 0/39 (0%)

Deaths: 0/39

Anastrozole

Serious: 2/40 (5%)

Deaths: 0/40

Serious adverse events (2 terms)

Reaction	System	Letrozole	Anastrozole
Sacroiliitis	Musculoskeletal and connective tissue disorders	—	—
Neuro event	Nervous system disorders	—	—

Other adverse events (5 terms — click to expand)

Reaction	System	Letrozole	Anastrozole
Fracture	Injury, poisoning and procedural complications	—	—
Hair loss	Skin and subcutaneous tissue disorders	—	—
Acne	Skin and subcutaneous tissue disorders	—	—
Scoliosis	Musculoskeletal and connective tissue disorders	—	—
Aggression	Nervous system disorders	—	—

Most-reported serious reactions: Sacroiliitis, Neuro event.

Data from ClinicalTrials.gov NCT02137538 adverse events section.

Sponsor's own description

The purpose of the study is to determine if there are differences in the final height or hormone profile of short pubertal boys placed on different forms of aromatase inhibitor now routinely used to increase stature: Anastrozole and Letrozole. It also should determine if there are differences in the side effect profiles of the two drugs to be used.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Anastrozole vs Letrozole to Augment Height in Pubertal Males With Idiopathic Short Stature: A 3-Year Randomized Trial.
   Zegarra W, Ranadive S, Toulan D, Neely EK. · · 2024 · cited 7× · PMID 39262574 · DOI 10.1210/jendso/bvae141