On 20 November 2018, the FDA approved the interferon-γ neutralising monoclonal antibody emapalumab (Gamifant®, Novimmune) for the treatment of adult and paediatric (newborn and older) patients with refractory, recurrent, or progressive primary haemophagocytic lymphohistiocytosis (HLH) or in patients intolerant to conventional HLH therapy.

Trial NI-0501-04

The multicentre, open-label, single-arm trial NI-0501-04 (NCT01818492) enrolled 27 paediatric patients with refractory, recurrent, or progressive primary HLH or those who were intolerant to conventional HLH therapy. Dexamethasone was provided as background HLH treatment for emapalumab doses between 5 to 10 mg/m²/day. All patients received prophylaxis for fungal infections, Herpes Zoster, and Pneumocystis jirovecii prior to emapalumab infusion. The primary efficacy endpoint was the overall response rate (ORR) at the end of treatment which was defined as either a complete or partial response or a ≥50% improvement from baseline of ≥3 HLH abnormalities.

Among the 27 paediatric patients, 7 complete and 8 partial responses were recorded and two patients had an HLH improvement resulting in an ORR of 63% (95% CI, 0.42-0.81; P=0.013).

Safety

Common adverse reactions in ≥20% of patients included infections, hypertension, infusion-related reactions, and pyrexia.

Full prescribing information Gamifant®