A Novel Immune Modulator for Patients With Necrotizing Soft Tissue Infections (NSTI): Results of a Multicenter, Phase 3 Randomized Controlled Trial of Reltecimod (AB 103)

Ann Surg. 2020 Sep 1;272(3):469-478. doi: 10.1097/SLA.0000000000004102.


Background and objective: Reltecimod, a CD 28 T-lymphocyte receptor mimetic, inhibits T-cell stimulation by an array of bacterial pathogens. A previous phase 2 trial demonstrated improved resolution of organ dysfunction after NSTI. We hypothesized that early administration of reltecimod would improve outcome in severe NSTI.

Methods: Randomized, double-blind, placebo-controlled trial of single dose reltecimod (0.5 mg/kg) administered within 6 hours of NSTI diagnosis at 65 of 93 study sites. Inclusion: surgical confirmation of NSTI and organ dysfunction [modified Sequential Organ Failure Assessment Score (mSOFA) score ≥3]. Primary analysis was modified Intent-to-Treat (mITT), responder analysis using a previously validated composite endpoint, necrotizing infection clinical composite endpoint, defined as: alive at day 28, ≤3 debridements, no amputation beyond first operation, and day 14 mSOFA ≤1 with ≥3 point reduction (organ dysfunction resolution). A prespecified, per protocol (PP) analysis excluded 17 patients with major protocol violations before unblinding.

Results: Two hundred ninety patients were enrolled, mITT (Reltecimod 142, Placebo 148): mean age 55 ± 15 years, 60% male, 42.4% diabetic, 28.6% perineal infection, screening mSOFA mean 5.5 ± 2.4. Twenty-eight-day mortality was 15% in both groups. mITT necrotizing infection clinical composite endpoint success was 48.6% reltecimod versus 39.9% placebo, P = 0.135 and PP was 54.3% reltecimod versus 40.3% placebo, P = 0.021. Resolution of organ dysfunction was 65.1% reltecimod versus 52.6% placebo, P = 0.041, mITT and 70.9% versus 53.4%, P = 0.005, PP.

Conclusion: Early administration of reltecimod in severe NSTI resulted in a significant improvement in the primary composite endpoint in the PP population but not in the mITT population. Reltecimod was associated with improved resolution of organ dysfunction and hospital discharge status.

Trial registration: ClinicalTrials.gov NCT02469857.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • CD28 Antigens / administration & dosage*
  • Debridement / methods*
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Drug Administration Schedule
  • Fasciitis, Necrotizing / therapy*
  • Female
  • Humans
  • Immunologic Factors / administration & dosage
  • Male
  • Middle Aged
  • Treatment Outcome


  • CD28 Antigens
  • Immunologic Factors
  • AB103

Associated data

  • ClinicalTrials.gov/NCT02469857