Apitegromab Dosing Calculator

Dose

Dose not yet publicly disclosed in detail

Frequency

Every 4 weeks

Duration

Phase 2 trial ongoing

Route

Intravenous infusion

Investigational combination with tirzepatide for lean mass preservation during weight loss

Dose

Apitegromab 10 mg/kg or 20 mg/kg IV every 4 weeks for 12 months in nonambulatory patients with Types 2 and 3 SMA aged 2-21 receiving nusinersen or risdiplam. Both doses contributed to a pooled 1.8-point HFMSE improvement over placebo (p=0.019).

Frequency

IV infusion every 4 weeks (Q4W)

Duration

12 months in the pivotal study

Randomized 1:1:1 to 10 mg/kg, 20 mg/kg, or placebo. Primary analysis pooled both dose groups. Individual dose-response differentiation not clearly reported. Background SMN-targeted therapy required in all participants.

Dose

Apitegromab 2, 10, or 20 mg/kg IV every 4 weeks in patients with Types 2 and 3 SMA aged 2-21. The 20 mg/kg dose in nonambulatory patients receiving nusinersen showed the strongest HFMSE improvements at 36-48 months.

Frequency

IV infusion every 4 weeks (Q4W)

Duration

12 months core study, extended to 48 months

Open-label active treatment design (no placebo). Long-term extension data showed sustained motor function gains. 48-month HFMSE change of +5.3 points at 20 mg/kg with nusinersen.

Dose

Apitegromab 10 mg/kg IV every 4 weeks in combination with tirzepatide in adults with BMI >=27 with comorbidities or BMI >=30. Preserved 54.9% of lean mass (p=0.001) vs tirzepatide alone at 24 weeks.

Frequency

IV infusion every 4 weeks (Q4W)

Duration

24 weeks

Proof-of-concept trial (n=100). Randomized 1:1 to apitegromab or placebo, all receiving tirzepatide. No serious adverse events or discontinuations related to apitegromab. Scholar Rock plans to develop SRK-439 (next-generation inhibitor) for the obesity indication.

Dose

Single ascending doses of 1, 3, 10, 20, 30 mg/kg IV and multiple ascending doses of 10, 20, 30 mg/kg IV in healthy adults. Linear, dose-proportional pharmacokinetics with half-life of 24-31 days.

Frequency

Single dose or multiple doses IV

Duration

Variable (Phase 1)

Safe and well-tolerated at all doses up to 30 mg/kg. No anti-drug antibodies detected. Dose-dependent target engagement confirmed by serum latent myostatin increases.

How much bacteriostatic water should I add to a 15 mg vial of Apitegromab?

The community standard is 2 mL of bacteriostatic water for a 15 mg Apitegromab vial. That gives a concentration of 7.50 mg/mL, so a 20 mg dose is 266.7 units on a U-100 insulin syringe. Adding 1 mL instead doubles the concentration to 15.00 mg/mL and halves the draw to 133.3 units. Less water = smaller injection volume but harder to measure precisely.

How many syringe units is a 20 mg dose of Apitegromab?

On a standard U-100 insulin syringe, a 20 mg dose of Apitegromab is 266.7 units when the 15 mg vial is reconstituted with 2 mL of bacteriostatic water (7.50 mg/mL). If you use 1 mL of bac water instead, draw 133.3 units (15.00 mg/mL).

What is the standard Apitegromab dose?

Community-reported protocols for Apitegromab typically use 20 mg once daily via Intravenous infusion. 20 mg is a common starting dose. Phase 3 clinical trial protocol; not yet commercially available

Where do you inject Apitegromab?

Apitegromab is typically administered intravenous infusion. Common subcutaneous sites are the lower abdomen (at least an inch from the navel), the outer thigh, and the love handles. Rotate sites with each injection to reduce localized irritation and bruising.

Can I use sterile water instead of bacteriostatic water for Apitegromab?

Bacteriostatic water (containing 0.9% benzyl alcohol as a preservative) is strongly preferred for multi-dose vials like Apitegromab because it inhibits microbial growth and lets a single vial be used over multiple weeks. Sterile water has no preservative and should generally be reserved for single-use preparations only.