COVID-19, syphilis, and biologic therapies for psoriasis and psoriatic arthritis: A word of caution

To the Editor: I read the timely and thought-provoking article about the coronavirus disease 2019 (COVID-19) pandemic and biologic therapy for psoriasis by Lebwohl et al.¹ The authors compiled research data about almost all the most commonly used biologics in dermatology and their rates of infection, upper respiratory infections, and nasopharyngitis based on current published studies.

However, I would like to offer a word of caution: the article is based on trials of biologic therapies, which are the criterion standard. It should be noted that certain groundbreaking (initial) adverse effects were published in the past as case reports or letters and may not have gotten much attention if published today. One of the foremost examples is the thalidomide tragedy. The initial adverse effects of thalidomide were described by Florence² and later, other workers reported the embryopathy adverse effects.³ More recently, Uslu et al⁴ described a unique case of possible reactivation of latent syphilis infection in a patient with psoriasis and psoriatic arthritis who was receiving therapy with interleukin-12/23 monoclonal antibody (ustekinumab). The authors suggested the possibility of reactivation of latent syphilis infection in their case, although they considered it unlikely. Similar reports had earlier appeared with antitumor necrosis factor-alpha therapy. The possibility that the natural progression of syphilis may have been accelerated by biologics in these cases cannot be completely excluded.⁵

Unlike syphilis, which is well known, the prognosis of COVID-19 cannot be predicted in individual cases (particularly in middle aged and older patients, with co-morbidities like diabetes mellitus or cardiovascular disease etc, if they are being treated with biologics). Therefore, in my opinion, the clinician must weigh the risk of loss of efficacy of a particular biologic in a responsive patient. It may be useful to consider that the patient is likely to be responsive to another biological agent when needed. Although the risk-to-benefit ratio must always be considered before discontinuing any effective medication, the unpredictable behavior of COVID-19 may be a priority at present. Patients who continue to receive therapy with biologics will need to be closely monitored as more knowledge about this infection becomes available.