Traditional immunosuppressive therapies inhibit upstream targets within the immune pathway, analogous to an axe chopping large branches. In inhibiting upstream targets, the immunological component responsible for a certain disease may be cut off, but the axe may have also chopped off a branch that fights infection or guards against cancer. Just as with an axe to a tree, the closer to the trunk that these medications take action, the more of the tree (the components of the immune system) will be affected. Targeted therapies are analogous to pruning shears, clipping off small branches in hopes of inhibiting only the parts of the immune system responsible for a disease. Directed use of pruning shears rather than an axe targets specific derangements in the immune pathway while leaving others intact, with the goal of maximizing treatment efficacy while minimizing side effects.
Two medications commonly used in psoriasis treatment, methotrexate and rizankizumab, can be compared using this model. Methotrexate is a traditional immunosuppressive that interferes with DNA replication. As all cells must synthesize new DNA, methotrexate can potentially act on many immune cell types in addition to the overactive lymphocytes causing inflammatory disease. Therefore, methotrexate is analogous to an axe, chopping at large branches of the tree. Rizankizumab is an immunomodulator specifically targeting IL-23, a prominent cytokine in psoriasis pathogenesis. Consequently, rizankizumab acts as pruning shears, cutting off smaller branches of the immune system “tree”.
The wealth of therapeutic options available to dermatologists is rapidly expanding. As we move forward in this era of emerging targeted treatments, our counseling methods must expand and evolve in parallel to new therapeutic options. Simplified, relatable, and visually engaging instruments such as this upside-down tree will aid clinicians in their responsibilities as patient educators.
2. Center for Drug Evaluation and Research (CDER). The Voice of the Patient: Psoriasis. U.S. Food and Drug Administration; March 17, 2016 2016.
3. Dzubur E, Khalil C, Almario CV, et al. Patient concerns and perceptions regarding biologic therapies in ankylosing spondylitis: insights from a large-scale survey of social media platforms. Arthritis Care Res. 2019;71(2):323-330.
4. Martinez B, Dailey F, Almario CV, et al. Patient understanding of the risks and benefits of biologic therapies in inflammatory bowel disease: insights from a large-scale analysis of social media platforms. Inflamm Bowel Dis. 2017;23(7):1057-1064.