How should crinecerfont (Crenessity) be started, what dose adjustments are needed, and what laboratory parameters should be monitored?

How to Start Crinecerfont (Crenessity): Dosing, Adjustments, and Laboratory Monitoring

Start crinecerfont at weight-based dosing twice daily with meals while maintaining stable glucocorticoid therapy, then gradually reduce glucocorticoids over 20-24 weeks based on androstenedione levels, monitoring for adrenal insufficiency and neutropenia.

Initial Dosing

Adults

• 100 mg orally twice daily (morning and evening with meals) 1

Pediatric Patients (≥4 years)

Weight-based dosing twice daily with meals 1:

• 10 to <20 kg: 25 mg morning, 25 mg evening
• 20 to <55 kg: 50 mg morning, 50 mg evening
• ≥55 kg: 100 mg morning, 100 mg evening

Critical: Administer with food - both morning and evening doses must be taken with meals 1

Glucocorticoid Management During Initiation

Do NOT reduce glucocorticoids below physiologic replacement doses at any time 1. This is the most critical safety consideration.

Initial 4-Week Stabilization Phase

• Maintain current glucocorticoid dose stable for the first 4 weeks 2, 3
• This allows assessment of crinecerfont's effect on androgen levels before dose adjustments
• Continue mineralocorticoid therapy unchanged 4

Weeks 4-24/28: Gradual Glucocorticoid Reduction

After demonstrating androstenedione control, begin gradual glucocorticoid reduction 5, 6:

Target glucocorticoid doses:

• Adults: Reduce toward physiologic replacement (15-25 mg/m²/day hydrocortisone equivalents) 6
• Pediatrics: Target 8-10 mg/m²/day hydrocortisone equivalents 3

Reduction strategy:

• Decrease by 10-25% every 2-4 weeks based on androgen control 5, 6
• Consider switching from long-acting (dexamethasone) to short-acting glucocorticoids (hydrocortisone) for better titration 6
• Adjust timing to mimic circadian cortisol patterns 6

Laboratory Monitoring Protocol

Baseline (Before Starting)

• Androstenedione (primary marker)
• 17-hydroxyprogesterone (17-OHP)
• Testosterone (especially in females)
• Complete blood count with differential
• Electrolytes, blood pressure (for mineralocorticoid assessment) 4

Week 4 Assessment

• Androstenedione: Should decrease substantially (expect ~50-70% reduction) 2, 3
• Goal: Maintain androstenedione ≤120% of baseline OR within reference range 2, 3
• If controlled, begin glucocorticoid reduction

Ongoing Monitoring During Dose Reduction (Every 2-4 weeks)

• Androstenedione before morning glucocorticoid dose 3
• 17-OHP levels 4
• Testosterone (females) or androstenedione/testosterone ratio (males) 7
• Neutrophil count: Monitor for neutropenia (14% of adults developed counts <2×10³/mcL) 1

Pediatric-Specific Monitoring

• Height and weight at each visit 4
• Bone age annually after age 2 years 4
• Growth velocity assessment 4
• Signs of virilization or premature bone maturation 4

Critical Safety Considerations

Adrenal Crisis Risk

The incidence of adrenal crisis was 1.6% in crinecerfont-treated adults 1. To prevent:

• Never reduce glucocorticoids below cortisol replacement needs 1
• Use stress-dose glucocorticoids for illness, trauma, or surgery 4, 1:
  • Infants/preschool: 25 mg hydrocortisone IV
  • School-age: 50 mg hydrocortisone IV
  • Adults: 100 mg hydrocortisone IV
• Educate patients on signs of adrenal insufficiency

Hypersensitivity Reactions

• Monitor for throat tightness, angioedema, rash (occurred after 3 days in one subject) 1
• Discontinue immediately if hypersensitivity occurs 1

Neutropenia

• Check CBC regularly during treatment 1
• 14% developed neutrophil counts <2×10³/mcL 1

Drug Interactions

With moderate CYP3A4 inducers (e.g., efavirenz, modafinil):

• Adults: Increase evening dose to 200 mg (morning stays 100 mg) 1
• Pediatrics: Increase evening dose proportionally per weight table 1

Common Pitfalls to Avoid

1. Reducing glucocorticoids too quickly - This is the most dangerous error. Reduce gradually over 20+ weeks 2, 3

2. Reducing below physiologic replacement - Always maintain adequate cortisol replacement (minimum 8-10 mg/m²/day in children, 15-25 mg/m²/day in adults) 1, 6

3. Not using stress dosing - Acute illness requires 3-4× maintenance glucocorticoid doses 4

4. Ignoring neutropenia - Regular CBC monitoring is essential 1

5. Taking without food - Absorption requires meal administration 1

6. Missing doses - If missed, take as soon as possible even if close to next dose, then resume regular schedule 1

Expected Laboratory Changes

By Week 4 2, 3:

• Androstenedione: 50-70% reduction
• 17-OHP: ~64% reduction
• ACTH: ~66% reduction
• Testosterone (females): 50-75% reduction

By Week 24-28 2, 3:

• Glucocorticoid dose reduction of 18-27% while maintaining androgen control
• 63% of adults and significant proportion of pediatric patients achieve physiologic glucocorticoid dosing

The key to successful crinecerfont therapy is the gradual, monitored reduction of glucocorticoids while ensuring androgen control and maintaining adequate cortisol replacement at all times.