Clinical Information

Risankizumab (Skyrizi, AbbVie) is a humanized IgG1 kappa therapeutic monoclonal antibody used to treat moderate to severe plaque psoriasis, ulcerative colitis, and Crohn disease. Risankizumab targets interleukin 23A (IL-23p19) binding with high affinity to the p19 subunit and inhibiting further action.

Therapeutic drug monitoring (TDM) has become standard of care in the gastroenterology practice for biologic therapies used in inflammatory bowel disease (IBD), Crohn disease, and ulcerative colitis. TDM is routinely used to assess loss of response to therapy and proactively manage patients taking tissue necrosis factor (TNF) inhibitors (eg, infliximab and adalimumab), alpha-4-beta7 integrins (vedolizumab), or IL12/23 blockers (ustekinumab). With the approval of risankizumab for IBD, TDM is expected to play an important role in managing loss of response to therapy and guide decision making for use of monotherapy or combination therapy.

Risankizumab is currently US Food and Drug Administration-approved for plaque psoriasis, psoriatic arthritis, ulcerative colitis, and Crohn disease.

Patients with plaque psoriasis or psoriatic arthritis are treated with 150 mg subcutaneously at weeks 0, 4, and every 12 weeks thereafter. The steady state maximum concentration (Cmax) and trough concentration (Ctrough) are estimated to be 12 and 2 mcg/mL, respectively.

Patients with Crohn disease are treated with 600 mg intravenously at weeks 0, 4, and 8, followed by 180 mg or 360 mg subcutaneously at week 12 and every 8 weeks thereafter. During induction weeks 8 through 12, the median Cmax is estimated to be 156 mcg/mL and the Ctrough is estimated to be 38.8 mcg/mL, according to the drug package insert. Steady state is achieved at 28 weeks after starting treatment in the dosing regimen for Crohn disease. Median Cmax and Ctrough concentrations measured during weeks 40 through 48 of maintenance phase (or weeks 52-60 from start of treatment) are estimated to be 14.0 mcg/mL and 4.1 mcg/mL, respectively, for 180 mg dose or 28.0 mcg/mL and 8.1 mcg/mL, respectively, for 360 mg dose.

Risankizumab is immunogenic, like other therapeutic monoclonal antibodies. Clinical trials have shown antibodies-to-risankizumab occur at rates of about 24% for plaque psoriasis, 12% for psoriatic arthritis, and 3.4% for Crohn disease.