Overweight and obese patients also require unique considerations when choosing a biologic. Infliximab is the only approved psoriasis biologic that utilizes proportional-to-weight dosing and hence may be particularly efficacious in patients with higher body mass. Ustekinumab dosing also takes patient weight into consideration; patients heavier than 100 kg should receive 90-mg doses at initiation and during maintenance compared to 45 mg for patients who weigh 100 kg or less. Other approved biologics also may be utilized in these patients but may require closer monitoring of treatment efficacy.
There are few serious contraindications for specific biologic therapies. Any history of allergic reaction to a particular therapy is an absolute contraindication to its use. In patients for whom IL-17 inhibitor treatment is being considered, inflammatory bowel disease (IBD) should be ruled out given the likelihood that IL-17 could reactivate or worsen IBD. Of note, TNF-α inhibitors and ustekinumab are approved therapies for patients with IBD and may be recommended in patients with comorbid psoriasis. Phase 2 and phase 3 trials have found no reactivation or worsening of IBD in patients with psoriasis who were treated with the IL-23 inhibitor tildrakizumab,6 and phase 2 trials of treatment of IBD with guselkumab are currently underway (ClinicalTrials.gov Identifier NCT03466411). In patients with New York Heart Association class III and class IV congestive heart failure or multiple sclerosis, initiation of TNF-α inhibitors should be avoided. Among 3 phase 3 trials encompassing nearly 3000 patients treated with the IL-17 inhibitor brodalumab, a total of 3 patients died by suicide7,8; hence, the FDA has issued a black box warning cautioning against use of this drug in patients with history of suicidal ideation or recent suicidal behavior. Although a causal relationship between brodalumab and suicide has not been well established,9 a thorough psychiatric history should be obtained in those initiating treatment with brodalumab.
Initiation of Therapy
Prior to initiating biologic therapy, it is important to obtain a complete blood cell count, complete metabolic panel, tuberculosis testing, and hepatitis B virus (HBV) and hepatitis C virus serologies. Testing for human immunodeficiency virus may be pursued at the clinician’s discretion. It is important to address any positive or concerning results prior to starting biologics. In patients with active infections, therapy may be initiated alongside guidance from an infectious disease specialist. Those with a positive purified protein derivative test, T-SPOT test, or QuantiFERON-TB Gold test must be referred for chest radiographs to rule out active tuberculosis. Patients with active HBV infection should receive appropriate referral to initiate antiviral therapy as well as core antibody testing, and those with active hepatitis C virus infection may only receive biologics under the combined discretion of a dermatologist and an appropriate specialist. Patients with human immunodeficiency virus must concurrently receive highly active antiretroviral therapy, show normal CD4+ T-cell count and undetectable viral load, and have no recent history of opportunistic infection.
Therapy should be commenced using specific dosing regimens, which are unique for each biologic (Table). Patients also must be educated on routine follow-up to assess treatment response and tolerability.
Assessment and Optimization of Treatment Response
Patients taking biologics may experience primary treatment failure, defined as lack of response to therapy from initiation. One predisposing factor may be increased body mass; patients who are overweight and obese are less likely to respond to standard regimens of TNF-α inhibitors and 45-mg dosing of ustekinumab. In most cases, however, the cause of primary nonresponse is unpredictable. For patients in whom therapy has failed within the recommended initial time frame (Table), dose escalation or shortening of dosing intervals may be pursued. Recommended dosing adjustments are outlined in the Table. Alternatively, patients may be switched to a different biologic.
If desired effectiveness is not reached with biologic monotherapy, topical corticosteroids, topical vitamin D analogues, or narrowband UVB light therapy may be concurrently used for difficult-to-treat areas. Evidence for safety and effectiveness of systemic adjuncts to biologics is moderate to low, warranting caution with their use. Methotrexate, cyclosporine, and apremilast have synergistic effects with biologics, though they may increase the risk for immunosuppression-related complications. Acitretin, an oral retinoid, likely is the most reasonable systemic adjunct to biologics because of its lack of immunosuppressive properties.
In patients with a suboptimal response to biologics, particularly those taking therapies that require frequent dosing, poor compliance should be considered.10 These patients may be switched to a biologic with less-frequent maintenance dosing (Table). Ustekinumab and tildrakizumab may be the best options for optimizing compliance, as they require dosing only once every 12 weeks after administration of loading doses.
Secondary treatment failure is diminished efficacy of treatment following successful initial response despite no changes in regimen. The best-known factor contributing to secondary nonresponse to biologics is the development of antidrug antibodies (ADAs), a phenomenon known as immunogenicity. The development of efficacy-limiting ADAs has been observed in response to most biologics, though ADAs against etanercept and guselkumab do not limit therapeutic response. Patients taking adalimumab and infliximab have particularly well-documented efficacy-limiting immunogenicity, and those who develop ADAs to infliximab are considered more prone to developing infusion reactions. Methotrexate, which limits antibody formation, may concomitantly be prescribed in patients who experience secondary treatment failure. It should be considered in all patients taking infliximab to increase efficacy and tolerability of therapy.