P059 Ex vivo comparison of baricitinib, upadacitinib, filgotinib and tofacitinib for cytokine signalling in human leukocyte subpopulations

Abstract

IntroductionBaricitinib (BARI), an oral selective Janus kinase (JAK) 1/2 inhibitor, approved in the EU for moderate to severe active RA.ObjectivesTo compare in vitro cellular pharmacology of BARI to upadacitinib (ABT), filgotinib (FILGO), and tofacitinib (TOFA), three JAK inhibitors (JAKis) currently approved or in clinical development.MethodsPeripheral blood mononuclear cells from healthy donors (n=6–12) were incubated with different JAKis. After cytokine stimulation, phosphorylated signal transducer and activator of transcription (pSTAT) levels were measured and IC50 calculated in phenotypically gated leukocyte subpopulations. Therapeutic dose relevance of in vitro analysis was assessed using calculated mean concentration-time (CT) profiles over 24 hour JAKi-treated subjects (BARI 4 mg QD; ABT 15 and 30 mg QD; FILGO 100 and 200 mg QD; TOFA 5 and 10 mg BID). Time above IC50 (T>IC; h/day) and average daily% inhibition of pSTAT formation (%SI) were calculated for each JAKi, cytokine, and cell type.ResultsTested cytokines did not signal in all cell types. When signalling was detected, IC50,%SI, and T>IC for a particular JAKi exhibited similar dose dependent inhibition across cell types. For JAK1/3 dependent signalling across 4 cytokines (IL-2, 4, 15, 21), IC50 for ABT and TOFA were more potent than BARI; FILGO was the least potent. Overlaid on CT profiles, this indicated generally higher%SI and longer T>IC for ABT and TOFA compared to BARI and FILGO. For IL-6 (JAK1/2),%SI and T>IC was TOFA>BARI/ABT>FILGO and for IL-10 (JAK1/TYK2),%SI was TOFA>BARI/ABT>FILGO. IFN-γ (JAK1/2) was modulated only by BARI, ABT, and TOFA. IFN-α (JAK1/TYK2) signalling was most potently inhibited by BARI and ABT. FILGO did not appear to modulate GM-CSF signalling (JAK2/2), while%SI and T>IC were similar between BARI and ABT.ConclusionsJAKis modulate distinct cytokine pathways to differing degrees and durations over 24 hour. BARI and FILGO inhibited JAK1/3 signalling less than ABT and TOFA. No JAKis agent potently or continuously inhibited an individual cytokine signalling pathway throughout dosing interval, implying the varying efficacy and safety profiles of JAKis across disease states.AcknowledgementsStudy supportEli Lilly and Company and Incyte Corporation. Encore of ACR/ARHP-2017 Annual Scientific Meeting, Nov 4–8, 2016; San Diego, CA, USA.Disclosure of interestNone declared

Janus kinase inhibitors for the treatment of rheumatoid arthritis demonstrate similar profiles of in vitro cytokine receptor inhibition

“…Indeed, time above IC 50 may be significant. 39 One observation with tofacitinib dosed QD vs BID suggests that some JAK effects may be more sensitive to daily drug holiday. In Limitations of this analysis must be considered.…”

“…Indeed, time above IC 50 may be significant. 39 One observation with tofacitinib dosed QD vs BID suggests that some JAK effects may be more sensitive to daily drug holiday. In a phase 2 RA study, changes in levels of hemoglobin and neutrophils from baseline to week 24 were less pronounced with tofacitinib 20 mg QD (0.01 g/dL and −0.43 × 10 3 /mm 3 , respectively) vs 10 mg BID (−0.34 g/dL and −1.20 × 10 3 /mm 3 , respectively).…”

“…Given that tofacitinib and baricitinib do not appear to differentially inhibit cytokine receptor signaling via JAK2 to a significant extent, alternative reasoning for the observed clinical difference may be important, for example, time course for inhibition. Indeed, time above IC 50 may be significant …”

Unraveling the Molecular Mechanism of Recognition of Selected Next-Generation Antirheumatoid Arthritis Inhibitors by Janus Kinase 1

“…Tofacitinib (CP-690550) is a type-I pan-JAK inhibitor that the FDA first approved to treat RA. ,, In the face of extensive kinome selectivity of tofacitinib, it has limited selectivity within the JAK family of kinases. It led to the discovery of JAK1-specific type-I inhibitors, such as baricitinib (INCB028050), upadacitinib (ABT-494), filgotinib (GLPG0634), , and itacitinib (INCB039110). , Baricitinib is used to treat moderately to severely active RA in adults . Upadacitinib is recommended to treat RA and other autoimmune diseases .…”

Clinical efficacy of new JAK inhibitors under development. Just more of the same?

“…Both JAK1 and JAK3 inhibition apparently are effective and one needs to explore the mechanistic pathways leading to efficacy. Just labelling for a certain specificity is not appropriate when one looks to the differences in ex vivo results and in vitro cellular pharmacology from baricitinib to upadacitinib, filgotinib and tofacitinib [ 33 ]. JAK inhibitors display different in vitro pharmacological profiles which, coupled to their in vivo pharmacokinetics, suggests that they modulate distinct cytokine pathways to differing degrees and durations over 24 h. Baricitinib and filgotinib inhibited JAK1/3 signalling to a lesser extent than upadacitinib and tofacitinib.…”