Biologic survival in hidradenitis suppurativa: much done, more to do
Authors: R. Hambly, B. Kirby
Journal: British Journal of Dermatology (2021)

Linked Article: Prens et al. Br J Dermatol 2021; 185:177–184. Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease, with multiple systemic comorbidities1 Treatment is challenging and adalimumab [tumour necrosis factor (TNF)-α monoclonal antibody] is the only licensed therapy. It is effective in approximately 50% of patients, based on Hidradenitis Suppurativa Clinical Response results from the phase III trials PIONEER I and II.2 In this issue, Prens et al. report real-world drug survival data for adalimumab and infliximab in HS.3 Until now, long-term data on adalimumab therapy was only available from the 3-year open label extension (OLE) of PIONEER I and II trials. This showed a sustained response of 52·3% to week 168 using last observation carried forward analysis.4 Subsequent post hoc analysis found, however, a dropout rate of 51 out of 88 patients in this OLE study.5 Clinical trial results do not always reflect daily clinical practice,6 hence studies such as the one by Prens and colleagues3 are important. The results of 148 patients who had at least 6 months' follow-up, implying at least a partial primary response, are reported. The drug survival of adalimumab at 12 and 24 months was 56·3% and 30·5% respectively, and for infliximab was 58·3% and 48·6% respectively. The main reason for discontinuation was loss of efficacy. Older age, longer disease duration, higher body mass index (BMI) and more severe disease were associated with longer adalimumab survival. This differs from factors that influence biologic survival in other conditions. In total, 56·8% of all patients underwent surgery excluding incision and drainage. Surgery during treatment predicted longer adalimumab and infliximab survival on univariate Cox regression analysis. Although not stated by the authors it is reasonable to assume that those who underwent surgery had more severe disease.7 The beneficial effects of surgery in this study may have influenced the univariate analysis results. It is recognized that higher BMI is associated with increased HS severity.8 The positive effects of surgery may explain in part the counterintuitive findings that patients with more severe disease and higher BMI had increased drug survival. Although comparisons of drug survival across disease groups should be done with caution, this study identifies lower drug survival for anti-TNF-α treatment in HS than is seen in psoriasis, rheumatology and gastroenterology cohorts. Concomitant therapy with additional immunosuppressants such as methotrexate and azathioprine is more common in rheumatology and gastroenterology and this may influence positively drug survival. It is also worth noting that 62·2% of patients in this study were taking concomitant medications for HS, most frequently antibiotics. The use of antibiotics and the need for surgery illustrates that anti-TNF-α therapies alone were not sufficient to control disease for the majority. This is a well done study but it is retrospective in design. It highlights the need for a multifaceted approach to people with HS where biologic treatment, concomitant antibiotics and surgery are needed. Prospective real-life registry data is required to further understand the natural history of therapeutic interventions in HS and to continue the recent significant advances in HS therapy. we thank Dr Rosalind Hughes, St Vincent's University Hospital, for providing critical review of this commentary. Open access funding provided by IReL. Roisin Hambly: Formal analysis (equal); Writing-original draft (equal); Writing-review & editing (equal). Brian Kirby: Conceptualization (equal); Supervision (equal); Writing-original draft (equal); Writing-review & editing (equal).