Ablynx announced that its partner, Merck KGaA has reported encouraging results from a study in psoriasis patients with the bi-specific Nanobody® anti-IL-17A/F (M1095). The trial was conducted in 41 patients with moderate-to-severe psoriasis with multiple ascending subcutaneous doses ranging from 30mg to 240mg administered on days 1, 15 and 29. The primary endpoints were safety, tolerability, immunogenicity and pharmacokinetics. Secondary endpoints were pharmacodynamics and efficacy. The doses of M1095 were well tolerated. No dose-dependent treatment-emergent adverse events were observed. Pharmacokinetic profiles demonstrated dose proportionality with the expected terminal half-life of 11-12 days. There was no apparent effect of anti-drug antibodies on pharmacokinetics. A reduction in disease activity, as measured by Psoriasis Area Severity Index (PASI) and improvement in static Physician Global Assessment (sPGA) was seen for all doses of M1095. At day 85, for the three highest dose groups (60mg, 120mg, and 240mg); PASI-75 (75% or more reduction in disease activity) scores of 100% were achieved versus 0% for placebo. In addition, all dose levels of M1095 showed 88-100% of patients achieving a minimal or clear sPGA score at day 85 versus 0% for placebo. Rapid onset of clinical effect was observed after the first dose and sustained out through to the conclusion of the study at day 85. The interleukin (IL)-17A/F bispecific Nanobody neutralizes the pro-inflammatory cytokines IL-17A and IL-17F, which are each expressed at inflammatory sites, and have both been implicated in the pathogenesis of psoriasis and several auto-immune disorders. The interleukin-17 (IL-17) family of cytokines includes six IL-17- family ligands, and five receptors. IL-17A is the most studied family member and most often mentioned as IL- 17. IL-17F is the closest relative to IL-17A based on sequence and receptor binding. Indeed, while both IL-17A and IL-17F exist as homodimers, an IL-17A/F heterodimer has also been described. In addition, both IL-17F and IL-17A bind the IL-17RA and IL-17RC receptors. A difference between IL-17A and IL-17F is that their expression may be differentially regulated at both the cell-type and transcriptional levels accounting for non-redundant roles in vivo. IL-17A and IL-17F are important mediators of local and systemic inflammation. Their activities are often additive or synergistic to that of other inflammatory mediators such as tumour necrosis factor (TNF). This described biology of IL-17A and IL-17F supports a role for both cytokines in the initiation and perpetuation of Th17-associated chronic auto-immune and inflammatory diseases and in subsequent organ damage. The bi-specific anti-IL-17A/F Nanobody (M1095) was discovered by Ablynx. Merck KGaA is now responsible for the clinical development and commercialization of M1095 with Ablynx set to potentially receive milestones and royalties as the programme progresses.