Abstract
IMPORTANCE: An increasing number of cutaneous adverse reactions resulting from use of programmed cell death protein 1 (PD-1) inhibitors have been described, but with relatively little focus to date on the timing of these reactions. OBJECTIVE: To determine the timing of cutaneous drug reactions after initiation of PD-1 inhibitor therapy. DESIGN, SETTING, AND PARTICIPANTS: This retrospective observational study included patients referred to an academic dermatology clinic by an oncologist from January 1, 2014, through February 28, 2018, with at least 1 skin biopsy specimen of a skin reaction associated with PD-1 inhibitor use. Participants were included if they had a biopsy-proven cutaneous reaction in response to a PD-1 inhibitor used alone or in combination with ipilimumab. EXPOSURES: All patients included in this study received pembrolizumab, nivolumab, or nivolumab with ipilimumab as immunotherapy for cancer. MAIN OUTCOMES AND MEASURES: The main outcome measure was time to onset of biopsy-proven cutaneous reactions that occurred during or after use of pembrolizumab or nivolumab. RESULTS: A total of 17 patients (12 men, 5 women; mean [SD] age, 68.6 [11.1] years) were identified who presented with cutaneous adverse reactions associated with PD-1 inhibitor therapy; these reactions included lichenoid dermatitis, bullous pemphigoid, erythema multiforme, eczema, lupus, and sarcoidosis. Twelve patients presented with reactions at least 3 months after beginning pembrolizumab or nivolumab therapy. The skin reactions presented a median (range) of 4.2 months (0.5-38.0 months) after drug initiation. In 5 cases, the cutaneous adverse reactions attributed to the PD-1 inhibitor therapy developed after the drug therapy was terminated. CONCLUSIONS AND RELEVANCE: Diverse cutaneous adverse reactions secondary to PD-1 inhibitor use may present with delayed onsets and even after discontinuation of therapy. Dermatologists should be aware of the potential for delayed presentations of cutaneous adverse reactions.